of the Conference CIE 2021
September 27 – September 29, 2021
CIE 2021 supported by:Sponsored by:

CIE 2021 - Abstract Booklet

Contents
PROGRAMME ..................................................................................................................... 3
INVITED PRESENTATIONS ................................................................................................12
ORAL PRESENTATIONS ....................................................................................................19
Session OS1 D4 – Road surfaces ............................................................................. 20
Session OS2 D3/D6 – Integrative lighting (1) ............................................................. 29
Session OS3 D1/D8 – Visual appearance .................................................................. 38
Session OS4 D2 – Measurement theory .................................................................... 45
Session OS5 D3/D6 – Integrative lighting (2) ............................................................. 52
Session OS6 D3 – Glare ........................................................................................... 60
Session OS7 D3 – Daylight ....................................................................................... 69
Session OS8 D1/D2 – Temporal light modulation ....................................................... 75
Session OS9 D4 – Benefits and disadvantages of road lighting .................................. 82
Session OS10 D3 – Residential lighting ..................................................................... 89
Session OS11 D2 – Measurement equipment evaluation............................................ 98
Session OS12 D2 – Measurement of materials and sources ..................................... 108
Session OS13 D1/D8 – Colour appearance models ................................................. 115
Session OS14 D3 – Lit environment ........................................................................ 123
Session OS15 D4 – Road lighting metrics................................................................ 132
Session OS16 D1 – Lighting trade-offs .................................................................... 139
Session OS17 D3 – Tools; Cultural concepts ........................................................... 148
Session OS18 D4 – Pedestrian-related issues ......................................................... 157
ORAL PRESENTATIONS IN WORKSHOPS ....................................................................... 165
Workshop WS2 Adaptive road lighting ..................................................................... 166
Workshop WS7 Revision of ISO/CIE 19476 and CIE S 025 ...................................... 171
POSTER PRESENTATIONS ............................................................................................. 176
WORKSHOPS .................................................................................................................. 283

2

CIE 2021 - Abstract Booklet

PROGRAMME

3

CIE 2021 - Abstract Booklet

Monday, September 27
Local Time
MYT

10:00 ‐ 14:00

Exhibitions,
Posters,
casual networking, MyCIE

14:00 ‐ 14:15

Opening

14:15 ‐ 15:15

INVITED SPEAKER
IP01
Yvonne de Kort, NL
AN INTEGRATIVE PERSPECTIVE ON DYNAMIC LIGHTING, AND HOW IT SHOULD BE STUDIED

15:15 ‐ 15:30

Break

15:30 ‐ 17:00

15:30 ‐ 15:45

15:45 ‐ 16:00

OS1
Road surfaces (D4)
Chair: Dionyz Gasparovsky, SK

OS2Integrative lighting 1 (D3/D6)
Chair: Adrie de Vries, NL

OP01

OP05

OP10

Valérie Muzet, FR

Myrta Gkaintatzi Masouti, NL

Shoma Amari, JP

IS IT POSSIBLE TO ACHIEVE QUALITY LIGHTINGWITHOUT CONSIDERING THE PHOTOMETRY OF
THE PAVEMENTS?

VALIDATION OF SPECTRAL SIMULATION TOOLSMODELLING OF PERCEPTUAL GLOSS BY PHYSICALFOR THE PREDICTION OF INDOOR ELECTRIC LIGHT
MEASUREMENT OF FLAT SURFACEEXPOSURE

OP02

OP06

OP11

Celine Villa, FR

Veronica Garcia Hansen, AU
CAPTURING THE LUMINOUS ENVIRONMENT IN
HOSPITAL ROOMS: AN OVERVIEW OF OCCUPANT‐CENTERED METHODS TO INFORM DESIGNPRACTICE
OP07

Xiaoyi Zhu, JP
EFFECT OF LIGHT SOURCE DISTANCE ON THE
DISCRIMINATION AND GLOSS PERCEPTION OF
PAPER

CHARACTERISATION OF LUMINESCENT ROAD
MARKINGS
OP03

16:00 ‐ 16:15

Yukie Miura, JP

Riho Ogawa, JP

EXAMINATION OF PSYCHOLOGICAL EFFECTS AND
THE ADDITIVITY ASSUMPTION IN THE STRESSEVALUATION OF CHROMATIC LED LIGHTINGSCOLOUR PERCEPTION OF LED POINT LIGHT
SOURCES IN SCOTOPIC VISION

OP08

Florian Greffier, FR

Henrika Pihlajaniemi, FI

HOW TO TAKE INTO ACCOUNT THE
HETEROGENEITY OF OPTICAL PROPERTIES OF A
PAVEMENT IN LIGHTING DESIGN ?

DESIGN FRAMEWORK FOR LIGHTING AND
OCCUPATIONAL WELL‐BEING IN UNDERGROUNDSPACES: CASE STUDY IN PYHÄSALMI MINE

16:30 ‐ 17:00

DISCUSSIONDISCUSSION

OS4
Measurement theory (D2)
Chair: Tobia Schneider, DE

WS1
Integrative lighting activities andapplications
Conveners: Peter Thorns, GB /Luc Schlangen, NL

WS2Adaptive road lighting
Convener: Dionyz Gasparovsky, SK

OP13

WP01

Thorsten Gerloff, DE

Constantinos Bouroussis, GR
A HOLISTIC METHOD FOR THE COMMISSIONING
AND OPTIMISATION OF ADAPTIVE ROAD
LIGHTING SYSTEMS USING LABORATORY AND
FIELD MEASUREMENTS
WP02

AN OVERVIEW OF IMPORTANT FACTORS TOCONSIDER WHEN CALIBRATING LEDS IN
PHOTOMETRY WITH DIFFERENT DETECTORS
OP14

17:45 ‐ 18:00

DISCUSSION

Break for supper/lunch/dinner/morning tea/breakfast

17:00 ‐ 17:30

17:30 ‐ 17:45

OP12

Laure Lebouc, FR
INFLUENCE OF ROAD SURFACES ON THE
CALCULATION OF A TARGET VISIBILITY TAKING
INTO ACCOUNT THE DIRECT AND INDIRECT
LIGHTING
OP04

16:15 ‐ 16:30

17:30 ‐ 19:00

OS3
Visual appearance (D1/D8)
Chair: Po‐Chieh Hung, US

Benjamin Ruggaber, DE
DEGREE OF EQUIVALENCE OF TRISTIMULUS
VALUES OF LEDS UNDER CONSIDERATION OF
MEASUREMENT UNCERTAINTY AND
CORRELATION

Dionyz Gasparovsky, SK
ASSESSMENT OF ROAD LIGHTING PERFORMANCEFOR TRAFFIC INTENSITY AND TRAFFIC DETECTION
BASED LIGHTING ADAPTATION

4CIE 2021 - Abstract Booklet
OP15
Forrest Webler, CH
18:00 ‐ 18:15

18:15 ‐ 19:00

SPECTRAL MEASUREMENT AND CLASSIFICATION
IN THE ERA OF BIG DATADISCUSSION

Break
WS3

19:00 ‐ 19:15

19:15 ‐ 20:45

OS5
Integrative lighting 2 (D3/D6)
Chair: Luc Schlangen, NL

Tutorial on
Enhancement of images for colour‐deficient
observers
Convener: Po‐Chieh Hung, US

WS4Practical determination of sampling intervalin photometry and radiometry
Convener: Tony Bergen, AU

OP16
Steffen Hartmeyer, CH
19:15 ‐ 19:30

TOWARDS A FRAMEWORK FOR LIGHT‐
DOSIMETRY STUDIES: METHODOLOGICALCONSIDERATIONS
OP17
Mihai Husch, RO

19:30 ‐ 19:45

NEW ANTIMICROBIAL STRATEGIE USINGCOMPOSITIONS WITH PHOTOCATALYTIC
PROPERTIES
OP18Janine Stampfli, CH

19:45 ‐ 20:00 THE LIGHT‐DOSIMETER – A NEW DEVICE TO HELPADVANCE RESEARCH ON THE NON‐VISUALRESPONSES TO LIGHT
OP19
Manuel Spitschan, GB
20:00 ‐ 20:15 LUOX: NOVEL OPEN‐ACCESS AND OPEN‐SOURCEWEB PLATFORM FOR CALCULATING AND
SHARING PHYSIOLOGICALLY RELEVANT
QUANTITIES FOR LIGHT AND LIGHTING
20:15 ‐ 20:45

DISCUSSION

20:45 ‐ 21:00

Break

21:00 ‐ 22:00

INVITED SPEAKER
IP02
Edward Nardell, US
VIRAL PANDEMICS: WHY GERMICIDAL UV AIR DISINFECTION IS ESSENTIAL
Networking Event

22:00 ‐ 23:00

Trivia Session
Hosted by Tony Bergen (AU), Vineetha Kalavally (MY), Peter Thorns (GB)

23:00 ‐ 00:00

Access Lobby
Access to prerecorded presentations from day before
Access to poster paper booths

5CIE 2021 - Abstract Booklet

Tuesday, September 28
Local Time
MYT
Access Lobby
Access to prerecorded presentations from day before
Access to poster paper booths

00:00 ‐ 14:00

14:00 ‐ 15:30

14:00 ‐ 14:15

14:15 ‐ 14:30

OS6Glare (D3)
Chair: Peter Thorns, GBOS7
Daylight (D3)
Chair: Martine Knoop, DE

OS8
Temporal light modulation (D1/D2)
Chair: Qian (Cherry) Li, CN

OP20

OP24

OP27

Simon Martin, BE

Gizem Izmir Tunahan, GB

Paul Dekker, NL

DAYLIGHT GLARE PROBABILITY PREDICTION FOR
AN OFFICE ROOM

THE ROLE OF DAYLIGHT IN LIBRARY USERS’ SEATPREFERENCES

FACILITY FOR CALIBRATION OF PHOTOMETERS
FOR TEMPORAL LIGHT MODULATION

OP21

OP25

OP28

Sneha Jain, CH

Yuki Oe, JP

ON SENSITIVITY TO GLARE AND ITS RELATIONSHIP
WITH MACULAR PIGMENT

EFFECTS OF THE TRIPLE SPLIT WINDOW SCREEN
ON VISUAL PRIVACY AND VIEW IN THE
RESIDENTIAL LIVING SPACE

O22

OP26

Anders Thorseth, DK
SENSITIVITY ANALYSIS ON THE EFFECT OF
MEASUREMENT NOISE AND SAMPLINGFREQUENCY ON THE CALCULATION OF THE
TEMPORAL LIGHT ARTEFACTS
OP29

Geraldine Quek, CH

Francisca Rodriguez, AU

Naomi Miller, US

ADAPTATIONS TO SUBJECTIVE INSTRUMENTS
FOR DYNAMIC VIEW ASSESSMENT EVALUATION

DEFINITION MODIFICATIONS FOR TEMPORAL
LIGHT MODULATION (“FLICKER”)

DISCUSSIONDISCUSSION

14:30 ‐ 14:45 USER EVALUATIONS OF CONTRAST‐DOMINANT
DISCOMFORT GLARE IN DIM DAYLIT SCENARIOS:PRELIMINARY FINDINGS
OP23
Gilles Vissenberg, NL
14:45 ‐ 15:00

15:00 ‐ 15:30

A GENERIC GLARE SENSATION MODEL BASED ON
THE HUMAN VISUAL SYSTEMDISCUSSION

Break

15:30 ‐ 15:45

WS5
Methods for measuring discomfort fromglare
Convener: Steve Fotios, GB

WS6
Pre‐vitamin D action spectrum: challenging
CIE towards a standard
Convener: Ann Webb, GB

WS7
Revision of ISO/CIE 19476 and
CIE S 025
Convener: Armin Sperling, DE
WP03
Udo Krüger, DE

15:45 ‐ 17:15

GENERAL V(λ) MISMATCH INDEX ‐ HISTORY,CURRENT STATE, NEW IDEAS
WP04
Ville Mantela, FI
NOVEL EVALUATION METHOD FOR GENERALPHOTOMETER MISMATCH INDEX f1'

17:15 ‐ 17:45

Break for supper/lunch/dinner/morning tea/breakfast

6

CIE 2021 - Abstract Booklet

Poster Session

17:45 ‐ 19:15

INVITED SPEAKER
IP03
Annika Jägerbrand, SE and Costis Bouroussis, GR

19:15 ‐ 20:15

MEASURES FOR REDUCING THE ADVERSE EFFECTS OF ARTIFICIAL LIGHT AT NIGHT: INTER‐DISCIPLINARY DEVELOPMENT AND PROGRESS

Networking Events

1. Fledgling Professsionals
Hosted by CIE President Peter Blattner (CH) and CIE VPT Jennifer Veitch (CA)

20:15 ‐ 21:15

2. A Taste of Malaysia ‐ Virtual Cooking and Gardening Tour
Hosted by Sarah Khong ‐ New Malaysian Kitchen Instructor (MY)OS9
Benefits and disadvantages of road lighting
21:15 ‐ 22:45(D4)
Chair: Sermin Onaygil, TR

21:15 ‐ 21:30

21:30 ‐ 21:45

OS10
Residential lighting (D3)
Chair: Nozomu Yoshizawa, JP

OS11
Measurement equipment evaluation (D2)
Chair: Thomas Reiners, DE

OP30

OP33

OP37

Maria Nilsson Tengelin, SE

Cláudia Amorim, BR

A NOVEL METHOD FOR STUDYING THRESHOLDLEVELS FOR POSITIVE PHOTOTAXIS IN INSECTS

LIGHTING CONDITIONS IN BRAZILIAN AND
COLOMBIAN HOME OFFICES: A PRELIMINARYSTUDY BASED ON OCCUPANT´S PERCEPTION

OP31

OP34

Yoshi Ohno, US
IEA 4E SSL ANNEX INTERLABORATORYCOMPARISON OF GONIOPHOTOMETERS
MEASURING SOLID STATE LIGHTING PRODUCTS –RESULTS
OP38

Steve Fotios, GB

Banu Manav, TR

Johannes Ledig, DE

INVESTIGATING LIGHT AND CRIME USINGAMBIENT LIGHT LEVELANALYSES ON OCCUPANT PATTERNS AND
ENERGY CONSUMPTION IN RESIDENTIAL
BUILDINGS INCLUDING THE COVID‐19 PANDEMICNONLINEARITY OF CHARGE ACCUMULATINGPIXEL MATRIX SENSORS USED IN IMAGINGLUMINANCE MEASUREMENT DEVICES

OP32

OP35

OP39

Chloe Robbins, GB

Barbara Matusiak, NO

Kinza Maham, FI

OPTIMISING ROAD LIGHTING TO REDUCE ROAD
TRAFFIC CRASHESHOME OFFICE SURVEY IN THE SCOPE OF THE IEASHC TASK 61, THE LIGHTING CONDITIONS FORSTUDENTSEMETHODOLOGIES TO MEASURE SPATIALUNIFORMITIES OF INTEGRATING SPHERES

OP36

OP40

Rengin Aslanoğlu, PL

Florian Stuker, CH

AN INTERNATIONAL SURVEY ON RESIDENTIAL
LIGHTING: ANALYSIS OF WINTER‐TERM RESULTS

sensLAB: TESTING MOTION AND PRESENCESENSORS FOR SMART LIGHTING

22:15 ‐ 22:45

DISCUSSIONDISCUSSION

22:45 ‐ 23:45

Access Lobby
Access to prerecorded presentations from day before
Access to poster paper booths

21:45 ‐ 22:00

22:00 ‐ 22:15

DISCUSSION

7

CIE 2021 - Abstract Booklet

Wednesday, September 29
Local Time
MYT
Access Lobby
Access to prerecorded presentations from day before
Access to poster paper booths

00:00 ‐ 14:00

OS12

WS8
Cone‐fundamental‐based colorimetry
Convener: Lorne Whitehead, CA

14:00 ‐ 15:30 Measurement of materials and sources (D2)

Chair: Gaël Obein, FR
OP41
Pablo Santafé‐Gabarda, ES
14:00 ‐ 14:15 EVALUATION OF THE BIDIRECTIONAL SCATTERING‐SURFACE REFLECTANCE DISTRIBUTION FUNCTION
FOR DIFFERENT LEVELS OF TRANSLUCENCY
OP42Dipanjana Saha, FR
14:15 ‐ 14:30

DEVELOPMENT OF A µBRDF
GONIOSPECTROPHOTOMETER FOR BRDF
MEASUREMENT ON TINY SURFACES
OP43
Yuqin Zong, US

14:30 ‐ 14:45

14:45 ‐ 15:30

ACCURATE MEASUREMENT OF ULTRAVIOLETLIGHT‐EMITTING DIODESDISCUSSION

15:30 ‐ 15:45

Break

15:45 ‐ 16:45

INVITED SPEAKER
IP04
Warren Julian, AU
SKYLIGHT AND SUNLIGHT; THE FORGOTTEN LIGHT SOURCES

Networking Event
16:45 ‐ 17:45

A Date with Malaysia ‐ Old Kuala Lumpur ‐ East West Connection Virtual 360 Tour
Hosted by Jane Rai ‐ Tour Guide (MY)

17:45 ‐ 19:15

17:45 ‐ 18:00

18:00 ‐ 18:15

OS13
Colour appearance models (D1/D8)
Chair: Kaida Xiao, GB

OS14
Lit environment (D3)
Chair: Veronica Garcia Hansen, AU

OS15Road lighting metrics (D4)
Chair: Steve Fotios, GB

OP44

OP48

OP53

Keyu Shi, CN

Hiroyuki Miyake, JP

Ulrika Wänström, SE

TESTING THE PERFORMANCE FOR UNRELATEDCOLOUR APPEARANCE MODELSQUANTIFICATION OF THE EFFECT OF LIGHTINGENVIRONMENT ON SPACIOUSNESS OF INTERIORSPACEIMPACT OF QUALITATIVE AND QUANTITATIVEMETHODS ON THE EVALUATION OF STREETLIGHTING UNIFORMITY

OP45

OP49

OP54

Ming Luo, CN

Nozomu Yoshizawa, JP

Alexander Basov, RU

TWO‐DIMENSIONAL COLOUR APPEARANCESCALES FOR COLOUR STIMULI HAVING HIGH
DYNAMIC RANGEA NEUROPHYSIOLOGY‐BASED MODEL TO
ESTIMATE VISIBILITY IN ACTUAL LIGHTINGENVIRONMENTNUMERICAL‐ANALYTICAL MODEL OF THE
LUMINANCE FACTOR OF AN ARBITRARY SURFACE

OP46

OP50

OP55

Balázs Vince Nagy, HU

Musashi Koyama, JP

Vincent Boucher, FR

8

CIE 2021 - Abstract Booklet
18:15 ‐ 18:30

18:30 ‐ 18:45

18:45 ‐ 19:15

CHROMATIC DISCRIMINATION THRESHOLDSOBSERVED IN CAM02‐UCS AND CAM16‐UCS

EFFECTS OF LUMINOUS COLOUR SHIFT Duv ON
COLOUR PREFERENCE

OP47

OP51

Ching‐Ching Wu, TW

Kei Suzuki, JP

REFERENCE WHITE IN A COMPLEX VIRTUALREALITY ENVIRONMENTTHE EFFECT OF LIGHTING ENVIRONMENT ON
FACIAL EXPRESSION PERCEPTION IN VIDEOTELECONFERENCINGDISCUSSIONDISCUSSION

19:45 ‐ 20:00

20:00 ‐ 20:15

20:15 ‐ 20:30

20:30 ‐ 20:45

20:45 ‐ 21:15

DISCUSSION

Break for supper/lunch/dinner/morning tea/breakfast

19:15 ‐ 19:45

19:45 ‐ 21:15

KEEPING THE BENEFIT OF ILMD’s HIGHRESOLUTION IN MEASURING LIGHTING QUALITY
PARAMETERS

OS16
Lighting trade‐offs (D1)
Chair: Yoko Mizokami, JP

OS17Tools; Cultural concepts (D3)
Chair: Cláudia Amorim, BR

OS18
Pedestrian‐related issues (D4)
Chair: Nigel Parry GB

OP56

OP60

OP64

Rugved Kore, US

Laura Bellia, IT

Khalidh Hamoodh, GB

DAMAGE REDUCTION WITH MAINTAINEDCOLOUR QUALITY OF ARTWORK UNDER RGB
PROJECTOR

VIRTUAL REALITY: A PROMISING APPROACH FOR
LIGHTING RESEARCH

THE VISUAL CUES USED TO EVALUATE OTHERPEDESTRIANS; FACE, BODY, OR SOMETHING
ELSE?

OP57

OP61

OP65

Suzuki Mizushima, JP

Nima Baradaran‐Razaz, SE

Steve Fotios, GB

THE DIFFUSENESS OF ILLUMINATION SUITABLE
FOR REPRODUCING OBJECT SURFACEAPPEARANCE USING COMPUTER GRAPHICS

HOW BUILDING INFORMATION MODELLING CANUSING RELATIVE VISUAL PERFORMANCE TOSUPPORT INCREASED RECYCLING OF LUMINAIRES PREDICT THE ABILITY TO MAKE INTERPERSONAL
AND LIGHT SOURCESEVALUATIONS

OP58

OP62

OP52

Maha Ishihara, JP

Hillevi Hemphaelae, SE

Belal Abboushi, US

A STUDY ON THE DIFFERENCES IN VISIONBETWEEN THE YOUNG AND THE ELDERLY INSIGNSVERAM, A SUBJECTIVE AND OBJECTIVE VISUALERGONOMICS RISK ASSESSMENT METHOD– A
DESCRIPTIVE PAPER OF THE OBJECTIVE RISKSILLUMINANCE AT THE EYE AS A SIMPLE METRICFOR DISCOMFORT GLARE FROM PEDESTRIANSCALE LUMINAIRES

OP59

OP63

Jennifer Veitch, CA

Gizem Izmir Tunahan, GB

COLOUR FIDELITY AND ILLUMINANCE TRADE‐OFF:TESTING LIGHTING VALUESCONCEPTUAL FRAMEWORK OF CULTURALBACKGROUND IN THE LIT ENVIRONMENTDISCUSSIONDISCUSSIONInteractive closing ‐ How did the conference go?
Quiz prizes, best student paper prize, best poster prize

21:15 ‐ 22:15

Time zones:
New Zealand:
Australia east coast:Central Europe:
Brazil:North America east coast:
North America west coast:

NZDT = MYT + 5 hours
AEST = MYT + 2 hours
CEST = MYT - 6 hours
BRT = MYT - 11 hours
EDT = MYT - 12 hours
PDT = MYT - 15 hours

9

DISCUSSION

CIE 2021 - Abstract Booklet

Poster presentations:
D1
PO01

Cehao

Yu

Netherlands

CHROMATIC LIGHT FIELD EFFECTS ON PERCEIVED MODELLING AND COLOURHARMONYTOWARDS AN AVIAN FLICKER VISIBILITY MEASURE

PO03

DraganSekulovski

Netherlands

PO04

Maria

Nilsson Tengelin

Sweden

PO05

Aayush

Bista

Nepal

PO06

Lorne

Whitehead

Canada

ARE THE DEMANDS IN ENTERTAINMENT LIGHTING TOO HIGH FOR WHITE LIGHT
EMITTING DIODES?
OPTIMUM SPECTRUM OF LED LIGHTING FOR CULTURAL AND HERITAGE SITE: A CASESTUDY OF 15TH CENTURY WORLD HERITAGE SITE IN NEPALDESIGN TRADE‐OFFS FOR MULTI‐PRIMARY BASED LIGHT SOURCES

PO08

Yuki

AkizukiJapan

SPECTRAL TRANSMISSION AND SCATTERING CHARACTERISTICS OF HUMAN SKIN

PO09

Yuki

Kawashima

United States

PO11

Yi‐Ming

Li

Chinese Taipei

PO12Viktoriia

RybinaRussia

PO13

Yuwei

Wang

United States

PERCEIVED CHROMA AND HUE CHANGES OF COLOURS AT HIGH ILLUMINANCELEVELS DUE TO HUNT EFFECT
VISUAL EFFECTS OF OBJECTS UNDER METAMERISM WITH MULTI‐SPECTRAL LIGHT
SOURCEAPPLICATION OF A STATISTICAL APPROACH TO THE DESCRIPTION OF COLOURPERCEPTION THRESHOLDSSUBJECTIVE EVALUATION OF VISUAL COMPLEXITY, CLARITY, AND PREFERENCE OF
INDOOR ENVIRONMENTS

PO14

Vyacheslav

Panin

RussiaPO15

Jiangen

Pan

China

PO17

AlexeyBartsev

RussiaPO18

Constantinos

Bouroussis

Greece

PO19

Petr

Kliment

Czech Republic

PO20

Alejandro

Ferrero

Spain

PO21

Philipp

Schneider

Germany

PO22

Tony

BergenAustralia

PO23

Oussama

BEN ABDELLAH

FrancePO24

Johannes

Ledig

Germany

PO25

Armin

Sperling

Germany

PO26

NéstorTejedor

Spain

PO27

Johannes

Ledig

Germany

PO28

David

Lerch

Germany

PO29

Igor

Zheleznov

RussiaPO30

DennisCorellDenmark

PO31

Zhafirah

AjrinaIndonesia

PO32

Brian HTLEE

Hong Kong

PO34

Alena

Kuznetsova

Russia

PO35

Roman

Dubnicka

Slovakia

PO36

TakaraTamuraJapan

D2
DEVELOPMENT OF A METHOD FOR MEASURING PPFD DISTRIBUTION OVER THE
TECHNOLOGICAL AREA OF A GREENHOUSE BY A MOBILE INSTALLATIONEVALUATION OF IMPEDANCE OF CABLES IN GONIOPHOTOMETRYILLUMINANCE DISTRIBUTION MEASUREMENT OF MUSEUM EXHIBITS USING
DIGITAL IMAGING LUMINANCE METERMETROLOGICAL CHALLENGES IN MONITORING OF SKY LUMINANCE DURING DAY
AND NIGHT BY USING LUMINANCE METERS AND RGB IMAGING SENSORSUNFILTERED TRAP‐BASED PHOTOMETER CALIBRATIONIMPACT OF THE NORMALIZATION OF THE SPECTRAL RESPONSIVITY ON THE
PERFORMANCE OF THE GENERAL V(λ) MISMATCH INDEXHANDLING OF CORRELATIONS OF SPECTRAL QUANTITIES IN TRACEABILITY CHAIN –BASICS FOR A PYTHON‐BASED ANALYSIS FRAMEWORKE
EXPERIMENTAL VALIDATION OF THE 200 NM LIMIT FOR MEASUREMENTS OFULTRIVIOLET RADIATION IN AIR
THE CORRELATED COLOUR TEMPERATURE: AN INFLUENTIAL PARAMETER IN AGEINGOLEDS
SIGNAL CHARACTERISTIC OF A CAMERA WITH AN INTEGRATING AMPLIFIER AND
LOGARITHMIC ENCODING AT THE PIXEL LEVELRevStdLED: A EUROPEAN PROJECT TO SUPPORT THE REVISION OF STANDARDSRELATED TO SOLID STATE LIGHTINGMEASUREMENT OF NORMAL / HEMISPHERICAL REFLECTANCE BY
GONIOSPECTOPHOTOMETRYUNCERTAINTY OF THE SPECTRAL MISMATCH ERROR IN MEASUREMENTS OF WHITE
LEDS WHEN REFERENCING THE LUMINOUS RESPONSIVITY TO AN LED REFERENCE
GENERIC MODEL FOR GONIOMETER GEOMETRIESSTUDY OF METHODS FOR MEASURING THE OPTICAL CHARACTERISTICS OF LOW‐PRESSURE MERCURY LAMPSCOMPARISON OF LUMINOUS FLUX MAINTENANCE METHODS, CONTINOUS VS.
ON/OFF CYCLESCHARACTERIZATION AND ANALYSIS OF SPECTRAL REFLECTANCE OF VARIOUS
INTERIOR MATERIALS DUE TO TUNABLE LED LIGHTINGCALIBRATION OF SPECTRAL IRRADIANCE SOURCES USING A FIBER‐COUPLEDSYSTEM
OPTIMISATION OF A MOBILE METHOD FOR MEASURING ROAD LIGHTINGCHARACTERISTICS (LUMINANCE AND ILLUMINANCE)INFLUENCE OF ROTATION ANGLE OF SQUARE LUMINAIRES ON MEASURED
PHOTOMETRIC PARAMETERS OF INDOOR WORPLACESESTIMATION OF COMPLEX LIGHT DISTRIBUTION CHRACTERISTIC BASED ON LIGHT
FIELDS

10

CIE 2021 - Abstract Booklet

D3
PO37

Kevin

BertinFranceAN OVERVIEW OF THE IMPACT OF STRAY LIGHT FROM COMMERCIAL GREENHOUSES

PO38

BarbaraMatusiak

Norway

PO39

Arjen

Mentens

Belgium

PO40

Dorukalp

DurmusUnited States

PO41

Anna

Pellegrino

Italy

PO42

Sevda

Aliparast

Turkey

PO44

Kairu

Inoue

Japan

LESSONS LEARNED FROM REGISTRATION OF OCCUPANCY AND USE OF LIGHTING IN
OFFICES, SCHOOLS, UNIVERSITIES AND INDUSTRY BUILDINGS, A CROSS COUNTRY
OPTIMIZING CAMERA PLACEMENT FOR A LUMINANCE‐BASED SHADING CONTROLSYSTEMA REAL‐TIME INTEGRATIVE LIGHTING SYSTEM FRAMEWORK BASED ON MACHINELEARNING
HIEQ LAB: A NOVEL FULL‐SCALE FACILITY WITH OCCUPANTS TO INVESTIGATEINTEGRATIVE LIGHTING AND HUMAN PERFORMANCE IN A MULTI‐DOMAINARTIFICIAL LIGHTING DESIGN WITH CONCEPT OF HUMAN CENTRIC LIGHTINGCRITERIA IN CELL OFFICES
CREATING A SENSE OF THE UNUSUAL WITH CHROMATIC LIGHT

PO45

Aya

Maeda

Japan

PO46

Ayana

MedeirosBrazil

PO47

Yukie

Sasajima

Japan

PO48

Alexandra

Bartseva

RussiaPO49

Tatiana

Meshkova

Russia

PO50

Hikdei

Yamaguchi

Japan

PO51

IntisarHussain

United Kingdom

PO52

Tongyue

Wang

China

PO53

EtsukoMochizuki

Japan

PO54

Roman

Dubnicka

Slovakia

PO55

LorrainCaumonFrancePO56

Om Sagar

Banjara

Nepal

PO57

Guillaume

Dotreppe

Belgium

TOWARDS AN IMPROVED V‐VLC OPTICAL CHANNEL MODELLING

PO59

Kai

Feng

China

PO60

Steve

Lau

China

PO62

AnnikaJägerbrandSwedenPO63

Jim

UttleyUnited Kingdom

A LABORATORY STUDY ON VISUAL AND EMOTIONAL COMFORT EVALUATION OF LED
WIDE BEAM ANGLE LAMPS : TAKING 3000K/ 4000K / 5000 K LINEAR LAMPS AS
THE IMPACT OF COLOURFUL AND DYNAMIC LED MEDIA FACADE AND BILLBOARDSON ASTRONOMICAL OBSERVATIONSA REVIEW OF THE IMPACT OF LIGHT POLLUTION ON ECOSYSTEMS AND SKY
BRIGHTNESSTHE EFFECT OF CHANGES IN LIGHT LEVEL ON THE NUMBERS OF CYCLISTS

PO64

Tomas

Novak

Czech Republic

PO65

Amira

AbouElhamd

MODELLING OF VERTICAL SURFACES RADIATION IN CONNECTION WITH THE
EVALUATION OF THE OBTRUSIVE LIGHT
United Arab Emirates USEFUL CONTRAST INDEX FOR ROADWAY LIGHTING STANDARDS

Ljiljana

UdovicicGermany

EVALUATION STRUCTURE ON PREFERENCE OF PAINTING’S APPEARANCE WITH LOW
REFLECTANCE IN THE MUSEUM LIGHTING ENVIRONMENT
THE LIGHT OF AMAZON ARCHITECT SEVERIANO MÁRIO PORTOSOFTNESS OF LIGHT PASSING THROUGH WINDOWS AND ITS RELATIONSHIP WITH
LUMINANCE GRADIENTDEVELOPMENT OF NEW STANDARDS FOR MUSEUM LIGHTINGSCALING OF SENSATIONS DURING THE PERFORMANCE OF VISUAL TASKS IN
RELATION TO HUMAN CENTRIC LIGHTINGISSUES AND COUNTERPLAN OF EVACATION CENTER AT NIGHT ‐ CASE STUDY OFNORTHEN GYMNASIUM IN SUZAKA CITY AFFECTED BY TYPHOON HAGIBIS IN 2019 ‐COMPARING THE PRIVACY VS DAYLIGHT COMPROMISE FOR DIFFERENT WINDOW
COVERINGSEVIDENCE‐BASED RESEARCH AND APPLICATIONS FOR HEALTH LIGHTING DESIGN IN
UNIVERSITY CLASSROOMSFIELD SURVEY ON LIGHTING ENVIRONMENT FOR WORK FROM HOME IN JAPANTEST TO ASSESS THE ACCURACY OF THE LIGHTING COMPUTER SOFTWARE WHEN
DESIGNING ROOMS WITH WINDOWSCOLOUR & LIGHT DESIGN: AMBIENCE AS AN ANSWER TO THE PROBLEMS OF AHEALTHY COLLECTIVE HOUSING.
INTEGRATION OF DAYLIGHT WITH ELECTRIC LIGHTING IN COMMERCIAL BUILDINGS:A CASE STUDY FROM NEPAL

D4

D6
PO67

LIGHT EXPOSURE OF WORKERS IN DIFFERENT OCCUPATIONS

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CIE 2021 - Abstract Booklet

INVITEDPRESENTATIONS

12CIE 2021 - Abstract Booklet

IP01
AN INTEGRATIVE PERSPECTIVE ON DYNAMIC LIGHTING, AND HOW IT SHOULD BE
STUDIED
Yvonne A.W. de Kort, NL
Technical University of Eindhoven

Abstract
1. Motivation, specific objective
Scientific literature tells us that lighting has the potential to make compelling contributions tophysical and mental health of individuals. Industry, project developers and even individual
users appear eager to ride this wave of promise and harvest the relevant biological andpsychological effects that isolated research outcomes promise. But we are gradually learningthat in lighting, the devil may not be in the details, but rather in the larger whole. Integrative
lighting was coined by the CIE to refer to lighting that is specifically intended to integratevisual and non-visual effects and to produce beneficial physiological and psychological effects
on humans. The term captures what many in our domain strive for but at the same time is stilla tall order for researchers and designers alike: integration may well prove to be a more
formidable ambition than hoped. The current presentation will reflect on relevant challenges
and how to potentially tackle them, specifically for the investigation of dynamic lighting.
2. Methods
We performed a structured review on ‘dynamic light’ and have performed a number of studies
on this phenomenon in controlled laboratory conditions as well as field settings. Without
exception, the ambition was to take an integrative perspective in each of these studies,through the inclusion of measures capturing subjective and objective responses, responses
that were experiential, behavioural and physiological in nature.
3. Results
The review taught us that the effects, nature, and even the intent of dynamic lighting are
under investigated and inconsistent across studies and implementations. But embarking on
the empirical study of this phenomenon ourselves, numerous theoretical, empirical andparticularly methodological issues arose, that almost disheartened us in our, perhaps overly
ambitious, goal to bring progress here. This paper will highlight some of the obstacles
encountered – from knowledge gaps on individual mechanisms, to wildly varying temporalscales at which they work, to limitations in the lab and in the field in intervention,measurement and analysis techniques – and aims to present ideas to overcome some of them.
4. Conclusions
Integrative Dynamic Lighting - Are we there yet? It may come as no surprise that, to date, theonly reasonable answer to this question is “no”. But importantly, we would like to convey themessage that the path towards it may call on us to not only perform additional research, but toalso reconceive research design, in terms of how, when, and where we perform it, from a new,integrative perspective.

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IP02
VIRAL PANDEMICS: WHY GERMICIDAL UV AIR DISINFECTION IS ESSENTIAL
Edward A. Nardell, USA
Professor of Medicine, Harvard Medical School; Associate physician, Brigham & Women’s
Hospital; Division of Global Health Equity; Division of Pulmonary and Critical Care Medicine ;Professor of Public Health T.H. Chan School of Public Health; Department of Environmental
Health; Department of Immunology and Infectious Diseases

Abstract
The Covid-19 pandemic is far from over, but it will not be the last pandemic – almost certainly
caused by viral pathogens, and likely to spread by aerosol – the most efficient mode of viraltransmission. Before SARS-CoV-2 emerged, an H1N1 pandemic was considered long overdue.
Aerosol transmission is now widely accepted as the principal way that Covid -19 is spread, as
has the importance of ventilation – natural and mechanical. Natural ventilation is critical, but
dependent on building design and occupant cooperation, where outsi de conditions permit
open windows.
But where present, other than for health care facilities, mechanical ventilation is designed for
comfort, not airborne infection control, and cannot achieve the 6 to 12 room air changes perhour (ACH) recommended for airborne infection control. More efficient air filters have been
recommended in ventilation ducts despite a lack of convincing evidence of any significant
spread of the SARS-CoV-2 virus spreads through ventilation systems. Most transmission
appears to occur in rooms where both an infectious source Covid-19 case and othersusceptible occupants share the same air.
Only two well-established, evidence-based room air disinfection technologies are available tosupplement mechanical ventilation: portable room air cl eaners and upper room germicidal UV
air disinfection. Portable room air cleaners (employing filters, UV, or both) can be effective,
but performance is limited by their clean air delivery rate relative to the room volume. Moving
enough air through portable room air cleaners to produce the equivalent of 6-12 ACH is
possible in theory, but the unobtrusive, quiet room units deployed often add no more than justone or two equivalent air changes. Producing 6-12 ACH would likely be noisy, draftee, andlikely require multiple units for other than small rooms. Recapturing and reprocessing justtreated air (short-circuiting) is another limitation of room air cleaners because the unit intake
location must be reasonably close to the unit discharge register.
SARS-CoV-2 and all other viral pathogens tested are highly susceptible to germicidal
ultraviolet GUV light, an 80-year-old technology that has been shown to safely, quietly,
effectively, and economically produce the equivalent of 10 to 20 or more equivalent ACH
under real life conditions. Studied extensively for safety and efficacy in the 30’s and 40’s,
interest in air disinfection waned after the introduction of vaccines for common communicableviral infections, and antibiotics for TB. Germicidal water disinfection h as remained standardpractice. Globally, the emergence of drug resistant TB over the last 25 years has led tocontinued commercial development, research, and application of upper room GUV in hospitals,
clinics, jails, homeless shelters, and other congregate setting in high-burden settings.
Upper room GUV fixtures are designed to keep the low-penetrating 254 nm irradiance in theupper room, safely above the heads of occupants. Upper room GUV irradiates and rapidly
disinfects the upper 15-25% volume of room air. Vertical air mixing between the upper andoccupied lower room results in equivalent air changes in the lower room routinely measured at
10-20 ACH without noise or drafts. Low velocity ceiling fans and other air mixers can further
increase lower room air disinfection. Well-established UV exposure limits for room occupants
allow both safe and effective installations.

14CIE 2021 - Abstract Booklet

Conclusions: Although vaccines are the main way that SARS-CoV-2 and future epidemic andpandemic airborne viruses will be controlled, transmission indoors can be reduced by effective air
disinfection. Beyond natural ventilation, where possible, the most practical, safe, and effective
technology for air disinfection is upper room UV.

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IP03
MEASURES FOR REDUCING THE ADVERSE EFFECTS OF ARTIFICIAL LIGHT ATNIGHT: INTER-DISCIPLINARY DEVELOPMENT AND PROGRESS
Jägerbrand, A.K.1, Bouroussis, C.A.2
Halmstad University, School of Business, Engineering and Science, Department ofEnvironmental and Biosciences, Rydberg Laboratory of Applied Sciences (RL AS), Halmstad,
SWEDEN, 2 Lighting Laboratory, National Technical University of Athens, GREECE
annika.jagerbrand@hh.se
1

Abstract
1. Motivation, specific objective
The use of artificial light at night (ALAN) in the outdoor environment may introduce negative
and unwanted side-effects such as light pollution, which can be defined as the generic sum of
the adverse effects of artificial light. ALAN can result in unwanted impacts on humans,
ecosystems and biodiversity. For example, light pollution may cause glare w hich can havenegative impacts on traffic safety. Other examples include the unwanted attraction of species
that exhibits positive phototaxis. The impact of light pollution can also result in lower survival
rates of nocturnal species that require dark areas for their well-being.
During recent decades, the adverse effects of ALAN have attracted more and more attention
in various research disciplines. Several studies have shown that light pollution is increasing
globally and regionally in specific regions. Many countries have therefore implemented
guidelines or legislation to mitigate the negative impact of light pollution.
There are also some voluntary initiatives for restrictions of outdoor use of light and light
pollution in specific areas by planning and following regulations for the use of outdoor
lightings, such as International Dark Sky Reserves, and a few other recommendations
available, such as, e.g., recommendations for the procurement of European road lighting.
However, such requirements are not always very useful or practical for implementation
especially in cases where outdoor lighting is applied for certain human activities and needs,
for example, in the urban environment. In such applications, ALAN is intended to create
visibility, guidance and comfort, or reduce the fear of crimes or for enhancing the traffic safety.
Under some circumstances, when lighting conditions are serving specific activities (e.g.,sports lighting), the guidelines for reducing the ecological impacts may be especiallychallenging to be applied. It is important to acknowledge the need for inter -disciplinary joint
efforts for successful development within the field of measures for reducing adverse impactsof light pollution. It seems crucial that experts from, for example, th e field of lighting
engineering and ecology (i.e., ecological impacts of ALAN) is collaborating.
This paper aims to present an updated overview and a state-of-the-art of available andeffective measures for reducing ALAN, which range from strategical and high-levelrecommendations to more practical and applicable lighting design recommendations andprinciples. Another aim is to identify prioritized future research questions and areas that will
enhance progress within the area.
CIE is actively working on the adverse effects of ALAN via two ongoing specific technicalcommittees, TC 4-58 “Obtrusive Light from Colourful and Dynamic Lighting and its Limitation”,
TC 4-61 “Artificial Lighting and its Impact on the Natural Environment” and a reportership DR
4-53 “Environmental Aspects of Obtrusive Light from Outdoor Lighting Installations”. One of
the motivations and a key objective of this paper is to create valuable inputs for the above
mentioned TCs concerning especially the potential proposed mitigation guideli nes.
2. Methods
We investigated the currently available measures suggested for reducing the adverse impactsof ALAN by reviewing the scientific literature. Another source of information was the16CIE 2021 - Abstract Booklet

recommendations that are discussed and adopted in the report that was produced by aspecific working group of a United Nations workshop with the task of the preparation of a
proposal to the Committee on the Peaceful Uses of Outer Space of United Nations Office forOuter Space Affairs.
Also, we developed and systematically categorized areas and measures for reducing ALAN
and identified future research questions for enhancing the progress within the area.
The recommendations proposed in this paper are developed having in mind all the aspects of
ALAN and the corresponding possible affected environmental groups, including humans,
fauna, and flora.
3. Results
Measures for reducing the adverse effects of ALAN are divided into three major groups:


Recommendations and legislation at national or international levels for the quantitativeand qualitative criteria on the selection of the areas to be illuminated or notRecommendations for technical and practical adaptations of the lighting design(lighting master planning), field measurement, and long -term monitoring

Recommendations for especially sensitive species, taxa, areas or ecosystems

Recommendations for potential legislation includes, for example, determination of which areas
to be illuminated, classification of ALAN-free zones, and limits of the amount of upwardemitted light. We will discuss what kind of measures that can be incorporated into planningdocuments, such as, for example, master planning or national legislation.
Recommendations for technical and practical adaptations will focus on, for example, spectral
power distribution, lighting control systems and adaptive lighting concepts, light distribution
and orientation, the directionality and polarization of the light, illumination levels for outdoor
environments, glare control, light measurements in the field, and ALAN and skyglow
monitoring.
Sensitive areas need to incorporate considerations of occasionally rare, endangered, andthreatened species. For recommendations in these kinds of areas, it is of crucial importanceto understand the species ecological requirements and the factual impacts of ALAN on thesurvival and fitness of relevant species. Various species and taxa have different tolerance for
ALAN. Relevant established recommendations are discussed.
4. Conclusions
In this work, we have assembled a set of practical and applicable recommendations that cansignificantly reduce the impact while offering a tool for decision -makers, engineers,
environmentalist, researchers, and other stakeholders. A new theoretical framework forreducing the negative effects of ALAN is proposed and discussed from a practical and inter disciplinary perspective.
This updated review of the various recommendations that are available for the mitigation of
the adverse effects of ALAN from the outdoor lighting shows that there are many possible
solutions for reducing light pollution, but that it may require good insight and knowledge inboth the impacts of the light pollution and an understanding of the technical solutions
available to choose the most effective and appropriate measures. Apart from ecological andlighting engineering research expertise, all stakeholder groups must also have a wide
experience in working with artificial lighting (i.e., theoretical knowledge, state of the art
technology and assessment tools).
Examples of future prioritized research efforts that would be beneficial to enhance progressfor reducing the adverse effects of light pollution are presented.

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CIE 2021 - Abstract Booklet

IP04
SKYLIGHT AND SUNLIGHT; THE FORGOTTEN LIGHT SOURCES
Warren Julian
University of Sydney, AUSTRALIA

Abstract
This paper will review the characteristics of skylight and sunlight, the fundamental sources ofdaylight, along with their reflected components, in the lighting of the built environment. In an
evolutionary sense, the characteristics of daylight together with the environment in whichhumans evolved, gave rise to the characteristics of our visual system. Until the invention ofelectric lighting, daylight determined how humans lived as a diurnal animal that was virtually
blind at night and in spaces that were devoid of daylight. As humans developed agriculture
and settled, there developed the need for permanent structures for shelter and social
activities. Those that remain reveal our dependence upon daylight for seeing indoors. The
industrial revolution, the precursor of the way most humans now live and work, led to factories
and other large structures that had to be designed to make use of the only plentiful lightsource at that time. Humans had developed various flame sources but these were all feeble,
expensive and dangerous to use. The office building also appeared at that time and wasconstrained in form due to the need to exploit daylight. The invention of electric lighting, about
150 years ago, along with mechanical ventilation, framed structures and th e lift broke thenexus between building forms and daylight. However, people have not evolved as quickly as
the built environment and we still need daylight, not only physically but also psychologically.
The issues created by our loss of contact with our evolutionary light source are significant but
mostly ignored as our homes and workplaces become more disconnected from the naturalenvironment. How we might reconnect in a real sense cannot be solved by electric lighting
alone.

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CIE 2021 - Abstract Booklet

ORAL
PRESENTATIONS

19

CIE 2021 - Abstract Booklet

Session OS1
D4 – Road surfaces
Monday, September 27, 15:30–17:00

20

CIE 2021 - Abstract Booklet

OP01
IS IT POSSIBLE TO ACHIEVE QUALITY LIGHTING WITHOUT CONSIDERING THE
PHOTOMETRY OF THE PAVEMENTS?
Muzet, V.1, Liandrat S.2, Bour V.3, Dehon J.4, Christory J.P5
Cerema ENDSUM, Strasbourg, FRANCE, 2 Cerema STI, Clermont-Ferrand, FRANCE,
3
AFE, Roissy, FRANCE, 4 Schreder, Liège, Belgique, 5 Consultant, Rambouillet, FRANCE
valerie.muzet@cerema.fr
1

Abstract
1. Motivation, specific objective
Road lighting installations are designed by calculating the performance in terms of luminancedistribution as defined in CIE 140:2019 and the EN13201:2015 European standard. Since thephotometric characteristics of the pavements are generally not measured, a standa rd r-table
as defined in CIE 144 is often used for lighting design.
These "standard" r-tables are more than 50 years old and several studies have shown thatthey are no longer representative of actual pavements. In the tunnels and the urban
environments, there is an important diversity of available materials and technologies like forexample clear pavements, cement concretes, concrete blocks, mastic asphalts and naturalstones sett paving. The photometric properties of some of them were never measured.
However, it was recently shown in the SURFACE European project that the standard r-tables
R3 and C2 are the most used all over the world, despite the fact that their use can generate
important errors (more than 30%) for the average luminance.
Nowadays the important renewing of lighting installation with a lot of LED relamping createsmajor new opportunities for road and public space operators. Can these new installations
comply with the EN13201 standard without taking into account the actual road photometry?
2. Methods
To address this question, a working group known as “Revêtements et Lumière“ for “Pavementbuilders and lighting designers” was formed. It brings together research laboratories, lighting
engineers, road and urban paving builders and administrator s.
The first step was to establish a representative panel of urban and interurban surfacing
materials including innovative French technologies. This panel includes 45 different
pavements:-

road surfaces with bituminous, synthetic or cement binder,-

more or less clear aggregates,-

raw pavements or pavements with initial surface treatment (sandblasted, broomed,...),-

different types of paving blocks (concrete blocks, natural stones sett paving).

The r-tables of these samples were measured with a laboratory gonio photometer in their new
condition (called T0) and after 30 months of natural outdoor ageing (called T30). The ageing
applied corresponds to what could be observed both on the central lanes of roads and on
urban pavements not used by cars, such as cycle paths, sideways or squares.
The second step consisted in conducting lighting simulations with two considered practicalcases.
1. Case of the classical relamping of a lighting installation where the geometry is
imposed and the pavement used for the lighting design remains the standard R3. The
quality of the lighting is then computed taking into account the measured r-table when
it is new and after 30 months.

21

CIE 2021 - Abstract Booklet

2. Case of the relamping of a lighting installation where the geometry is imposed and thepavement used for the lighting design is the stabilized pavement measured at T30.
The quality of the lighting is then also computed with the corresponding new pavement.
After all the simulations have been performed, the quality of the lighting obtained is analyzed
by comparison with the criteria defined in the EN 13201 standard.
3. Results
The results of photometric measurements of pavements in their new condition at T0 confirm
that there is an enormous diversity of behaviours. After 30 months, this variety fades a little
but remains very significant. In particular, a drop in specularity is observed on the vast
majority of pavements. This evolution is really important for pavements that were initially very
specular. It is also confirmed that the standard CIE tables do not allo w this diversity to betaken into account.
In case 1 of the lighting simulations, the led relamping is designed with the standard R3
pavement. When the photometry of the different type of pavements is integrated into thesimulation to calculate the luminance and uniformity levels, the requirements of the standard
are rarely met for the pavements in their initial state. With the measurements carried out inthe stabilized condition, there is still a high proportion of non -compliant photometric results.
In case 2 of the lighting simulations, the led relamping is designed while taking into accountthe stabilized r-table of each measured pavements (T30). In this condition, the requirementsof the standard are always fulfilled and the installed powers can be lowe r. If we simulate thelighting quality for the corresponding new pavements at T0, the standard is not always fulfilled
but the discrepancies with the limits are always moderate.
4. Conclusions
When a lighting installation is renewed, it is fundamental to t ake into account the pavement
photometry. With the usual practice of considering a standard r-table, the EN 13201 criteria
are not fulfilled, especially in terms of luminance uniformities. The diversity of photometry intoday's pavements is huge and taking them into consideration can increase the quality oflighting and provide significant energy savings.
With the constitution of a measurement database of actual pavements, this project willcontribute to the CIE TC 4-50 (Road surface characterization for lighting applications) andwork on EN 13201 standard.

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CIE 2021 - Abstract Booklet

OP02
CHARACTERIZATION OF LUMINESCENT ROAD MARKINGS
Villa, C., Bremond, R., Eymond, F., Saint-Jacques, E.
Université Gustave Eiffel, COSYS, PICS-L, F-77454 Marne-la-Vallée Cedex 2, FRANCE
celine.villa@univ-eiffel.fr

Abstract
1. Motivation, specific objective
The visibility of road markings helps motorists to control their trajectory and to anticipate it.
This is especially true at night, when other visual cues are less visible. In unlit areas, retro reflective markings are visible when illuminated by vehicle headlights. Nowadays, innovative
products may increase the visibility distance of visual cues, improving the guidance in unsafe
situations (such as fog, nighttime curves, low vision drivers). In partic ular, luminescent roadmarkings are being developed in order to allow the markings to be visible beyond theheadlamp beams. Luminescent properties enable light emission of the markings after
absorption of photons from sunlight or headlamps with a delay fro m a few nanoseconds toseveral hours. The intensity of this emission depends on the quantity and the spectrum of thelight previously absorbed.
To be applied on the road, luminescent markings must ensure performance at least equivalent
to traditional markings, especially in terms of colour and brightness during the day, and retro reflection at night. In addition, the characterization of the performance of this product requires
understanding of the temporal evolution of its colour and luminance. Standards al ready exist
for safety luminescent products, used for emergency signalling in buildings, based on theperformance during the first hour of emission. In the road context, we are interested in longer
emission times, in various nighttime illumination conditio ns, with road traffic, and in smallviewing angles, corresponding to the vision of a motorist or a cyclist.
This paper proposes a method to characterize the performance of luminescent road markings.
The potential use of this type of product in different ro ad scenarios is also discussed.
2. Methods
The visibility distance of luminescent markings varies during the night together with theemitted light. To assess the benefit of these paints, it is interesting to compare theirperformance with that of traditional road marking. It is to be noted that the purpose ofluminescent road markings is not to improve visibility in the headlamp beam but is to bevisible beyond it.
To quantify the light emission over time, measurements were conducted in laboratory. First,
the luminescence luminance in the dark was measured after a prior constant excitation, during
at least six hours. However, the emission in complete darkness is a theoretical reference
situation, which does not correspond to the real situation on the road. T o study the effect ofnighttime lighting conditions, two scenarios were also studied in the laboratory: constant low
illumination (such as moon, light pollution, urban areas), and periodic lighting, simulating
automotive traffic. The measurements were carried out on luminescent paints applied onaluminium and asphalt plates. Luminescence luminance was also measured after an artificial
ageing with a Wehner & Schulze machine. From these laboratory measurements and thecalculation method proposed in the COST 331 report, the visibility distance of the luminescentmarking beyond the headlamp beam was estimated, and compared to the visibility distance ofa traditional retroreflective marking.
To investigate more realistic conditions, measurements were also carrie d out on luminescentmarkings applied on real pavements. Their luminance were measured in an urban innovation
demonstrator located in a climatic chamber during and after three simulated twilights,
representative of those occurring in France. The time cours e of the twilight was simulated by

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CIE 2021 - Abstract Booklet

decreasing a controlled artificial sun during the two hours before civil twilight. In addition, afollow-up of luminescent markings on a real road was carried out, just after application andthen after 8 and 14 months of vehicular traffic.
3. Results
The luminescent luminance during the emission under constant low illumination is higher thanduring emission in the dark. The significant point is that the difference between the two isstable over time, and proportional to the illuminance (for E ≤ 0.1 lx). The expected andobserved effect of periodic traffic on luminescence emission also is an increase of luminanceover time (with respect to the dark emission), and this luminance deviation is constant overtime. These results make it possible to model the effect of periodic traffic on the luminance ofluminescent markings.
Visibility distance calculations were conducted based on the emission curves computed fromthe measurements in dark and the offsets due to constant illuminat ion and simulated traffic.
Finally, luminance variations observed at night on a real-world road confirmed the influence ofnighttime illumination conditions on product performance, and therefore the difficulty ofcharacterizing these products from onsite measurements. A computational method wasdeveloped to study the degradation of the luminescence due to traffic, irrespective of theambient nighttime lighting.
4. Conclusions
The measurements, carried out on samples in the laboratory and in a controlled env ironment,
have made it possible to isolate several factors influencing the performance of luminescentpaints.
For equivalent performance (in terms of RL and Qd), luminescent markings could strengthen
the visual guidance of drivers on the road by increasing the visibility distance beyond theheadlamp beams during the first few hours of the night. Improved performance may last
longer under certain favorable nighttime lighting conditions and with traffic. Without
automotive lighting, especially on unlit cycle paths, it seems that a gain can be obtained
compared to traditional markings, mainly at nightfall, during the end of twilight and during thefirst few hours of the night. In general, outside the beam of the headlights, luminescentmarkings are of interest when the luminescence significantly increases the luminance of themarking compared to the reflection alone, which is possible in low light conditions (end of
twilight, night, rain / night fog) on unlit roads or paths.
These conclusions are mainly based on measurements conducted on samples in thelaboratory (dry sample, controlled temperature, artificial polishing), in a controlledenvironment (artificial twilight), and on the visibility calculations carried out with the COST
331 method. They need to be confirmed by more systematic on-site measurements, under
different conditions (e.g. temperature, humidity). The deployment of these products on
experimental sites, and in situ monitoring methods will provide feedback on sustainability andincreased visibility whatever the external conditions.

24CIE 2021 - Abstract Booklet

OP03
INFLUENCE OF ROAD SURFACES ON THE CALCULATION OF A TARGET VISIBILITY
TAKING INTO ACCOUNT THE DIRECT AND INDIRECT LIGHTING
Lebouc, L.1, 2, 4, Boucher, V.2, Greffier, F.2, Liandrat, S.3, Nicolaï, A.1, Richard, P.4
1
Spie batignolles malet, Toulouse, FRANCE
2
Cerema, Laboratory of Angers, FRANCE
3
Cerema, Laboratory of Clermont-Ferrand, FRANCE
4
University of Angers, LARIS, SFR MATHSTIC, FRANCE
laure.lebouc@spiebatignolles.fr

Abstract
1. Motivation, specific objective
Performance requirements for road and tunnel lighting are defined in CIE (International
Commission on Illumination) or CEN (European Committee for Standardization) documents.
These texts specify performance criteria based on the average luminance of the ro ad surface,
the general and longitudinal uniformities of lighting to satisfy the visual needs of users. They
also describe the methodology for performing these calculations when dimensioning an
installation.
To go further, in our opinion, a visibility calculation is a necessary complement, especiallysince one of the main functions of lighting is to make an obstacle on the road visible and thus
enable a user to avoid it. We propose to use Adrian's well-known visibility level model for roadlighting applications, a model that was included in the CIE documents a few years ago andthen removed.
Adrian deals with the detection of 10-minute angular size target, which refers to a square
target of approximately 20cm side placed 86m in front of a vehicle, and he c alculates its
contrast with its background by evaluating the corresponding luminance levels. However,when it is used in lighting simulations, the calculated luminance of the target only considers
the direct lighting, i.e. the light coming directly from th e luminaires.
Therefore, we propose to study the influence of the pavement on the target visibility
calculation and thus take into account the indirect illumination due to the light that arrives on
the target after reflection on the road surface.
2. Methods
We have developed a simulation that allow us to vary lighting and road surfaces. From thissimulation, the visibility level (VL) of a target positioned at each point of the normative grid for
performance calculation can be determined.
In order to look at the influence of the road surface on the visibility calculation, the VL iscalculated for four lighting situations with four different very heterogeneous road surfaces(from light to dark, from diffuse to specular). The VL is evaluated by applying Adria n’s modelfrom direct lighting and then taking into account the reflections of the lighting on the pavement.
This is done by cutting the road in front of the target into surface elements and by evalu ating
the angles α, β, and γ between each element and the target. It is then necessary to know theproperties of the pavement for directions of observation α greater than 1°. Also, we will use
experimental data obtained with a gonio-reflectometer for angles between 1° and 45°. As six
measured r-tables for different viewing angles are available for each road surface, the valueof the reflection coefficient in a given direction is determined by interpolation. From this, theluminance of the target due to the reflection of the lighting on the pavement is deduced. The
total luminance of the target is the sum of this luminance and that obtained only with direct
lighting. Thus, we obtain the luminance of the target and then the VL.

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CIE 2021 - Abstract Booklet

3. Results
First, to validate our simulation, we calculate the luminance from the luminaires and the roadsurface and compare the values obtained with analytical data.
Then, we perform the calculation of the complete VL taking into account the light reflections
on the pavement by interpolating the value of the reflection coefficient from r -tables measured
for six different observation angles. This allows us to evaluate the influence of the pavement
on target visibility calculations.
4. Conclusions
The impact of the reflected luminance measurement on visibility will be exposed and we will
see the influence of the road surface. The discussion will focus on whether or not the roadsurface should be taken into account in the target visibility calculation based on its diffusingor specular properties.

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OP04
HOW TO TAKE INTO ACCOUNT THE HETEROGENEITY OF OPTICAL PROPERTIES OFA PAVEMENT IN LIGHTING DESIGN ?
Greffier, F.1, Muzet, V.2, Boucher, V.1
1 Cerema EEL, Angers, FRANCE
2 Cerema ENDSUM, Strasbourg, FRANCE
florian.greffier@cerema.fr

Abstract
1. Motivation, specific objective
Performance requirements for lighting installations are defined in the CIE technical documents
or in European standards. For drivers of motorized vehicles, the main criteria of lighting
quality are based on the luminance of the road surface (average luminance, overall uniformity,
longitudinal uniformity). These documents also specify the methodology for performing
calculations in designing or optimizing a lighting installation and achieving the necessary
performance.
The optical properties of a pavement are fundamental in these calculations. The pavement
ability to reflect light provides the average level of luminance required by users. Uniformities
allow to evaluate the homogeneous distribution of lighting on the road surf ace. They are thus
linked to the photometric characteristics of the luminaire, to the geometry of the lighting
installation but also to the optical properties of the pavement, especially if these latter are
heterogeneous.
Recent studies suggest that these properties should be better taken into account in lighting
calculations and that the use of standard r-tables defined by the CIE should be reconsidered.
With some lighting design software, it is now possible to use the complete measured r-table ofa pavement. Using the real photometric characteristics of the road surface can improve thequality of lighting, reduce energy costs and limit obtrusive light.
However, as always in the use of a measurement, the question of its accuracy must be asked,
not only about uncertainty but also about representativeness, here from a spatial point of view.
Indeed, a r-table measurement is often punctual. For example, the measurement is carriedout in the laboratory with a gonio-reflectometer on pavement samples, either new or obtained
after coring the pavement. It can also be performed directly on site with a portable gonio reflectometer. Whatever the measuring instrument, the aim is always to characterize a surface
of about 100 cm² and then to generalize its properties to the whole infrastructure. With
portable devices, several measurements are possible in different places of the road, resulting
in a set of different r-tables which reflect the heterogeneity of the pavement. How does thisheterogeneity affect a lighting calculation? What is its impact on the average luminance anduniformities? What methodological recommendations can be made to better integrate it andensure optimal use of a r-table measurement? We propose here some initial answers.
2. Methods
We evaluated the impact of heterogeneity in the optical properties of a pavement along theimplementation of a lighting calculation. For this purpose, numerous r-tables were measured
on an experimental site composed of a two-lane roadway lit by luminaires spaced 29 m apart.
The measurement points were defined in accordance with the normative CIE calculation grid.
Two additional r-tables were also measured based on the methodology usually used with ourportable gonio-reflectometer, i.e. providing one r-table in the tyre tack and another in thecentral track.
In a first step, we calculated for the different r-tables their lightness coefficient Q 0 and their
specularity factor S1. Q 0 and S1 are traditionally used to take into account differences
between pavements. In a second step, the r-tables measured at different grid points were27

CIE 2021 - Abstract Booklet

simultaneously implemented all in a lighting calculation. The average luminance anduniformities values obtained are considered in our study as reference values. Then, in order
to simulate the use of one r-table measured on a sample or at one single point, the r-tables
were used individually in lighting calculations. The average luminance and uniformities values
obtained were compared to the reference values. Additional calculations were performed withr-tables measured in the tyre track and in the central track as well as with the standard r-tablecorresponding to the pavement.
To compare all these results, we defined a metric based on the values of average luminanceand uniformities by associating the two traffic lanes. The relevance of this metric as anindicator of pavement heterogeneity was evaluated by comparison with values deviations of
Q 0 and S1 and then with a calculation of values deviations on whole r-tables.
3. Results
First, the interest of measuring the properties of a pavement is once again confirmed bycomparing the results of the calculations with those obtained with a standard r-table.
Concerning the pavement heterogeneity, the absolute deviations obtained with respect to thereference values encourage to characterize the pavement at different points to better
integrate its optical characteristics variability. We have shown that lightness coefficient Q 0 and
specularity factor S1 are not sufficient to directly link this variability with the fluctuations of
average luminance and uniformities. To overcome this drawback, we have defined a new
metric that provides a good correlation between the pavement heterogeneity and the quality
criteria dispersion of a lighting installation.
4. Conclusions
Integrating the real properties of pavements in lighting design should now become the rule inorder to optimize artificial light at night. It is therefore necessary to be able to measure theseproperties while ensuring an experimental protocol offering a g ood spatial representativenessof the measurement.
The study provides methodological guidelines for making on-site measurements
representative of the optical properties of pavements and their variability. The defined
heterogeneity indicator represents an interesting tool to better consider the whole pavement
properties for the optimization of lighting installations.

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Session OS2
D3/D6 – Integrative lighting (1)Monday, September 27, 15:30–17:00

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OP05
VALIDATION OF SPECTRAL SIMULATION TOOLS FOR THE PREDICTION OF INDOORELECTRIC LIGHT EXPOSURE
1

Pierson, C.1, Gkaintatzi-Masouti, M.2, Aarts, M.2, Andersen, M.1
EPFL, Lausanne, SWITZERLAND, 2 TU/e, Eindhoven, NETHERLANDS
clotilde.pierson@epfl.ch

Abstract
1. Motivation, specific objective
A new area of research, the non-visual effects of light, has emerged in the field of lighting withthe discovery of the ipRGCs (intrinsically photosensitive retinal ganglion cells), a new class ofphotoreceptors in the eye. In the presence of light, the ipRGCs express a photopi gment, themelanopsin, which mediates several behavioural and physiological responses in humans,such as the synchronization of the circadian clock to the light/dark cycle, the sleep propensity,
the inhibition of pineal melatonin secretion, etc. Consequently, our ocular light exposure
affects our health, well-being, and productivity through these responses. As we typicallyspend around 90% of our time indoors, there is an urgent need to anticipate the impact ofbuilding design and electric lighting decisions on the occupants’ light exposure in order to
optimize our built environment according to occupants’ psychological and physiological needs.
Our non-visual responses to light depend on various aspects of the light exposure, among
which its intensity and timing, as well as its spectral content. The non-visual system is indeed
more sensitive to short-wavelength light due to the contribution of the ipRGCs, althoughknowledge concerning the extent to which rods and cones also play a role in driving non visual effects is still growing. Unlike the visual responses for which light is described solely
based on the photopic action spectrum and its related photometric units, there is no single
action spectra for non-visual responses. To provide guidance for the description of light in thecontext of non-visual effects, the CIE therefore recommends the use of a framework based on
α-opic spectral sensitivity functions, quantities, and metrics. The application of this framework
requires to evaluate light radiometrically, and not photometrically. Such change in theevaluation of light implies that most current light simulation platforms are not appropriate forthe study of non-visual effects, as they are usually based on a three-dimensional colour spaceand photometric quantities.
Two spectral simulation tools, ALFA and Lark, have been developed recently to alleviate thisproblem and support the study of indoor spaces in relation to the non -visual effects of light.
Both tools rely on the physically accurate Radiance rendering engine, but Lark offers a 9channel “spectral” resolution while ALFA allows for an 81-channel resolution. What remains
unclear about these tools is how representative they are of real lighting conditions
experienced indoors. In a previous study, both tools were tested for their accuracy inpredicting building occupants’ daylight exposure in terms of spectral irradiance over time. In
order to provide a comprehensive validation of these tools, the aim of this study is todetermine the accuracy of ALFA and Lark in simulating actual electric light conditions
experienced indoors.
2. Methods
The methodology applied in this study consists in comparing spectral irradiance measured
under electric light conditions at three desk positions in an office -like laboratory module
against the corresponding spectral simulation outcomes.
Spectral irradiance and vertical illuminance are measured at eye level in seated position in
front of the desks using an Ocean Insight USB4000 spectrometer and a Hagner luxmeter. The
experiment includes three electric lighting scenarios: fluorescent tubes (Philips TBS600 1xTL5
49W HFP, ~3000K), warm LED (Philips PowerBalance recessed tunable RC464B PSD
W60L60 1 xLED80S TWH, ~2700K) and cool LED (Philips PowerBalance recessed tunable30

CIE 2021 - Abstract Booklet

RC464B PSD W60L60 1 xLED80S TWH, ~6300K). The light sources were selected based on
their non-continuous spectral power distributions (unlike the continuous daylight spectrum),which might make their simulation more dependent on channel resolution. The placement of
the desks includes one position with mostly direct, one with only indirect, and one with a
combination of direct and indirect light exposure. Daylight is not present during themeasurements.
Using the .ies files of the different luminaires tested and their measured spectral power
distribution, the spectral irradiance is simulated for each electric light scenario and each desk
position in both Lark and ALFA. The simulation error is then computed through two error
metrics: the median relative bias error (MRBE) and the normalized root mean square error(NRMSE), representing respectively the bias error and the variance error.
3. Results
Preliminary results suggest that both ALFA and Lark provide relatively accurate results for theprediction of photometric quantities under electric lighting. The comparison between thevertical illuminance measured and simulated under the fluorescent light scenario shows anerror similar to what can be expected from a standard Radiance RGB simulation under
daylight, i.e., within the ±15% range, though the bias error is shown to be heavily influenced
by the light loss factor input.
The simulation error in terms of spectral irradiance was also computed, and a sensitivity
analysis of that simulation error was conducted, that focused on the impact of the electric lightsource, of the desk position, and of the type of light exposure (e.g., mainly direct, only indirect,
both direct and indirect light).
4. Conclusions
In this study, two spectral simulation tools are tested for their accuracy in predicting building
occupants’ electric light exposure in terms of spectral irradiance. The results from this study
are compared to those from a former validation study under daylight conditions, so as toevaluate to what extent the spectral resolution of the simulation tool may influence theaccuracy of the simulated spectral irradiance under electric light conditions, which have lesscontinuous spectral power distributions than daylight. Once validated under both daylight andelectric light conditions, spectral simulation tools like Lark or ALFA can provide a powerfulsupport for decision-making regarding light exposure when it comes to meeting physiologicalneeds in indoor environments.

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OP06
CAPTURING THE LUMINOUS ENVIRONMENT IN HOSPITAL ROOMS: AN OVERVIEWOF OCCUPANT-CENTERED METHODS TO INFORM DESIGN PRACTICE
1

Garcia-Hansen, V.1, Rodriguez, F. 1 Ong, R. 1
Queensland University of Technology, Brisbane, AUSTRALIA
v.garciahansen@qut.edu.au

Abstract
1. Motivation, specific objective
Hospitals have shown a trend to decrease patients’ average length of stay (ALoS) to cover for
an increasing population demand. Shortening the length of stay is associated with hospitalefficiency and a positive impact on health workers. Further, it is associated with decrease drisks of hospital-acquired infections, and minimized symptoms of depression among patients.
Since shortening ALoS has direct benefits for health workers and patients alike, design
strategies should focus on improving the environmental indoor conditions, so that fast
recovery is achieved. One important aspect to consider are the effects induced by theluminous environment over the patients’ stay.
Interventions using dynamic lighting systems in hospitals settings have provided substantive
evidence of the positive effects of lighting on chronobiologic responses from patients andhealth workers. Along with evaluating electric lighting interventions, researchers havepositioned the need of investigating daylighting cycles to increase well -being in hospitalsettings. Scholars have long demonstrated that the provision of daylight and views in patients’rooms can decrease medication intake, increase satisfaction, and shorten ALoS. Researchers
have also proved that continuous access to appropriate daylighting condi tions helps
increasing workers’ alertness and enhance job satisfaction. Despite the body of evidence
demonstrating the importance of the luminous environment for health workers and hospitalpatients, these research outcomes have not been translated into pr actical design principles
that cover for potential conflicts between the requirements and needs of hospital users. One
possible reason is that the design of the hospitals’ luminous environments have relied on theinteraction between luminous conditions and clinical records from patients, disregarding that
other occupant-centred factors (e.g., cultural preferences, demographic requirements) may
also inform the requirements for what will constitute a healthy luminous environment in
hospital rooms.
The ubiquity of non-invasive sensors to monitor indoor photometric conditions and the raise of
ethnographic studies in hospital environments may help to bridge the gap between clinical -ledresearch and occupant-centred solutions for informing design practice. Recent studies
following this interdisciplinary approach have delineated design responses for blindautomation in open plan offices and home adaptions for aging in place. Thus, wehypothesized that similar principles can inform the design of hospital rooms for i ncreasingalertness and shortening the length of stay. To move in this direction, it is first required tomap post-occupancy and participatory methods in hospitals and examine the links between
them, so that these can be integrated into a 24h lighting fram ework that covers for occupants’needs and wants. In this study, we present the results of a systematic review on post occupancy and participatory methods in hospitals and introduce an occupant -centered
framework for investigating luminous environments in hospital rooms.
2. Methods
To increase reliability, a systematic search of peer-reviewed articles was conducted in
PubMed and Scopus considering a 10-year publication range. First, a list of keywords was
defined to structure the literature screening (i.e., Hospital, Room, Lighting, Daylighting,
Window, View, Patients, Inpatients, Nurses) for terms contained in the article title, abstract, or
keywords. Next, citation searching was conducted among the studies, which included peer reviewed papers using similar descriptors to those established in the first selection. To ensure

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internal validity, a first filtering criterion based on the abstract content was defined, excluding
papers whose research focus was other than environmental evaluation or occupants’impressions in hospital settings. We verified the refined sample using a full -text sift to ensure
pertinence and defined a second filtering criterion based on the type of study. Using thisfiltering technique, the evidence base was consolidated. Next, we conduc ted a thematic
analysis to refine the areas that encompassed the main dimensions of the study.
3. Results
Several post-occupancy and co-design methods were retrieved from this literature search.
These included a combination non-obtrusive techniques to capture indoor environmental
conditions (i.e., LiDAR sensing methods, simulations of circadian potential, thermal video
recordings, embedded photometric instruments) and ethnographic methods to capture varying
occupants’ responses to the hospital setting (i.e., observations, interviews, surveys, diary
entries). Advantages and limitations were documented for each of them. Opportunities arisingfrom the integration of different disciplinary techniques were also explored.
4. Conclusions
This study introduced an occupant-centred framework for investigating luminous environments
in hospital rooms. It is based on the systematic review of literature in post -occupancy and codesign methods in health environments. It is expected that this framework will help to bridge
the gap between clinical-based and participatory research outputs for informing design in
hospitals.

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OP07
EXAMINATION OF PSYCHOLOGICAL EFFECTS AND THE ADDITIVITY ASSUMPTION
IN THE STRESS EVALUATION OF CHROMATIC LED LIGHTINGS
1

Miura, Y.1, Oe, Y.1, Yoshizawa, N.1
Tokyo University of Science, Chiba, JAPANyukie1226m@gmail.com

Abstract
1. Motivation, specific objective
In recent years, LED lighting has become widespread and light that deviates significantly fromthe vicinity of the Planckian locus (hereinafter referred to as chromatic light) has become
more familiar. While chromatic light can create an impressive space, it is inferior in visibility
and workability. Therefore, in order to apply it to a real space, it is necessary to pay enoughattention to psychological and physiological effects, and photometric quantities should beclarified to predict them in advance.
The purpose of this study is to confirm psychological effects using multiple chromatic lights
including monochromatic lights and mixed colour lights, and to examine whether additivity
regarding irradiance can be established for the evaluation of stress, which is caused by mixed
colour lights made from two types of monochromatic lights. If the additivity is established, theeffect of mixed colour lights on stress can be predicted from that of monochromatic lights.
2. Methods
Subject experiments were conducted in the experimental space designed like a living room
(3.4m in width, 2.4m in depth and 2.7m in height). Two sofas and a table were placed, and thesofas were arranged so that the lines of two subjects’ sight did not always intersect and thesubjects were sufficiently exposed to light from LED luminaires. There were 25 subjects (14males and 11 females) with an average age of 21.5 years old. All subjects had normal colour
vision.
There were three monochromatic lights: blue, green, and red light have a relatively narrowfrequency band. For each mixed colour light, three types of colour were created so that threeplots of them were evenly spaced on the line segments formed by connecting two points ofmonochromatic lights on the CIE 1976 (u',v') chromaticity diagram. The lighting conditions
were blue light at 120lux of vertical eye illuminance, 3 types of magenta light at 53l ux, 3 typesof cyan light at 53lux, and 3 types of yellow light at 53lux. The analysis included the results ofthe previous studies: white light with correlated colour temperature of 2700K , 4000K and
6500K at 53lux; red light at 8, 26, 40, 53 and 120lux; green light at 8, 26, 40, 53 and 120lux;
blue light at 8, 26, 40 and 53lux; and 3 types of magenta light at 53lux.
Two lighting conditions were prepared in one experiment, and the order of the lighting
conditions was random. The experiment consists of five phases. Phase1: 6 minutes ofadaptation in the dark, Phase2: KAPLA (French building blocks), Sudoku (number puzzle),
and sketching work for 8 minutes each under the first lighting condition, Phase3: 6 minutes ofadaptation in the dark, Phase4: Same contents as Phase2 under the seco nd lighting condition,
Phase 5: 6 minutes of adaptation in the dark. For each lighting condition, psychologicalevaluation was performed twice: immediately after the start of the exposure to light and 1 hour
after the start of the exposure. There were seven evaluation items: "stress", "sleepiness","motivation", "seeing clearly", "eye strain", " anxiety", and "preference". It was carried out by
the 9-point Likert scale.
3. Results
There was a significant difference (p <0.05) between white light conditions a nd all chromatic
light conditions in "stress" and "preference" at 53lux. This indicates that chromatic lights are
more stressful and undesirable than white light.

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Two-way ANOVA was performed under the conditions of monochromatic lights at 8, 26, 40, 53,
and 120lux in order to investigate the effect of light colour, the effect of illuminance, and theinteraction of light colour and illuminance on the psychological evaluations. Only light colour
had an effect on the three items of "stress", "seeing clearly", and "preference."
Next, focusing on "stress", it was examined whether there is additivity regarding irradiance atthe same illuminance when mixed colour lights are made from two monochromatic lights. On ascatter plot showing the relationship between irradiance and "stress", if the plots of mixed
colour lights are located between those of the two monochromatic lights that compose themand a linear relationship is established, it can be said that there is additivity in stressevaluation. The plots of magenta lights were located between that of the red and the blue
lights, and a linear relationship was fairly well established at 26l ux and 53lux (26lux: R² = 0.58,
53lux: R² = 0.56). The same positional relationship was plotted at 120l ux, but a linear
relationship was not established (R² = 0.06). The reason why the additivity was somewhat
established for the magenta light at 26lux･ 53lux may be that the spectral distributions of the
red and the blue light used in this condition hardly overlapped. The yellow and the cyan lights
were plotted in the same positional relationship, but a linear relationship was weaker than thatof magenta at 53 lux (yellow: R² = 0.28, cyan: R² = 0.39). This is thought to be due to theoverlap of the spectral distributions of the red and the green lights, or the green and the blue
lights, which make the yellow and the cyan lights respectively.
4. Conclusions
Analysing the results of the experiments, it became clear that only light colour has an effecton psychological stress within the range of the conditions discussed in this paper. Further, inthe colour mixing of independent monochromatic lights whose sp ectral characteristics do notalmost overlap, additivity is possibly established for stress evaluation. In this case, it may bepossible to predict the psychological stress caused by the mixed colour light s from thatcaused by the monochromatic lights. In the future, it will be necessary to consider whether or
not additivity, not only on the psychological effects but also the physiological ones, isestablished by using a wider range of illuminance and chromaticity lighting conditions.

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OP08
DESIGN FRAMEWORK FOR LIGHTING AND OCCUPATIONAL WELL-BEING IN
UNDERGROUND SPACES: CASE STUDY IN PYHÄSALMI MINE
Pihlajaniemi, H.1, Pujol, M.1, Liikkanen, J.1
1
University of Oulu, Oulu, FINLAND
henrika.pihlajaniemi@oulu.fi

Abstract
1. Motivation, specific objective
There is a growing tendency for mining activity around the world and, on the other hand, newuses for underground spaces of the mines that are finishing their operation, are sought. In
underground spaces, lack of daylight may produce disorders in the biological cl ock of workers
and have many negative physiological and psychological effects. Besides the traditional
means of illumination, new LED lighting technologies, which allow the dynamic changes of thelighting intensity and spectral composition of white light, provide means to support workers’
daily rhythm with circadian lighting. The effects of lighting, however, are not only physiological,
and there are several other factors related to lighting as a design task while the humanexperience of light is multifaceted. A suitable lighting supports visual performance of worktasks, and glare-free lighting provides visual comfort and contributes to safety. The
underground working environments, especially mine environments, have their own challenges.
The great contrasts of illuminance and brightness between different areas may cause
adaptation problems, discomfort and hazard. As the connection to daylight and the intrinsic
awareness of exit route is missing, the unconscious and cognizant sense of security may
suffer. A successful lighting design should consider concurrently the physiological, visual, andpsychological influences of light and the challenges of the underground context.
The objective of this paper is to illustrate the design problematics of lighting environm ent ofunderground workspaces through a case study project in Pyhäsalmi mine, Finland. The paper
proposes a holistic design framework for lighting, which supports occupational well -being inunderground spaces, based on the results from the case study with realized intelligent lighting
pilot environment.
2. Methods
The case study site in Pyhäsalmi mine situates in almost 1,5 km depth - the deepest
underground location in Europe. The mining activities will soon be ending, and new purposes
for the underground environments are being developed. The methods used in the study were
the following: 1) an analysis of the research-by-design process applying scenario method, 2)
real-world piloting, and 3) qualitative semi-structured interviews. In the research-by-designphase, visions were created for refurbishment of two areas of the mine – the personnel
restaurant Retka and the underground laboratory Lab 2. The design process was supported
by preliminary interviews of the workers in the mine, which evaluated their exper iences ofworking in the underground location and the existing lighting conditions, and lighting needs
related to the work. Several scenarios and concepts for using adaptive and intelligent lighting
were created and studied. These utilized both the princip les of circadian or biodynamic
lighting related to human physiology, and factors of architectural lighting related to visual andspatial experience, functionality, aesthetics and meanings. During the project, an undergroundoffice in the mine was equipped with adaptive and intelligent lighting solutions, and a living
lab environment for testing the effects of lighting for well -being was created. Four different
lighting scenarios were tested both in the winter period and in the summer period. The mine
workers experiences of the scenarios and the developed lighting conditions of the office were
evaluated with interviews in both periods.

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3. Results
The resulting design framework presents the essential design aspects, which should beconsidered while designing lighting for underground spaces from the perspective ofoccupational well-being. The general aspects – visual, safety, time, control, and technology –have their manifestations both on the physiological and functional level, and on thepsychological and atmospheric level. These can then be interpreted to context-related design
factors – in our case representing the specific design needs related to mine environments.
These factors, along with general design aspects, are elaborated in the paper, referring toprevious studies of experience of light and other environmental factors in undergroundenvironments.
4. Conclusions
The case study in Pyhäsalmi mine revealed that lighting design for underground environments
is a complex design task, where contextual factors must be considered. Mine environment has
special conditions and work tasks, which have specific needs for visual performance andvisual comfort. In underground locations, the sense of space and orientation are important,since they relate to the sense of security and safety. Intelligently controlled, biodynamic
lighting can support the circadian rhythm of underground workers, however, since theilluminances of different mine spaces vary greatly and workers spend long periods in dark
environments, the successful control strategies differ from the ones suitable for normal
working environments. In underground locations, it is important to support the workers’ senseof time with visual cues. The automated lighting control and the individual control supplement
each other. Individual user needs should be balanced with multi -user aspects. Additionally,harsh conditions in mine locations set high demands for technical durability and robustness oflighting equipment and systems.

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Session OS3
D1/D8 – Visual appearance
Monday, September 27, 15:30–17:00

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OP10
MODELLING OF PERCEPTUAL GLOSS BY PHYSICAL MEASUREMENT OF FLAT
SURFACE
Tanaka, M., Amari, S., Horiuchi, T.
JAPANmidori@chiba-u.jp

Abstract
1. Motivation: specific objective
The question of how humans perceive object qualities has been actively discussed in recent
times. Regarding perceptual qualities, recent studies showed that perceptual gloss has a
psychological and physiological effect like boosting consumer confidence. The gloss of an
object can be physically measured using a gloss meter. However, recent research revealed
that physical gloss and perceptual gloss do not always match, and in the CIE JTC 17(D1/D2/D8), consideration for gloss measurements and gloss evaluation methods werelaunched. The purpose of this study is to derive a modelling of perceptual gloss by comparing
psychometric experiments to physically measured values for flat objects.
2. Methods
We derived a model through multiple regression analysis using the data obtained bymeasured physical features and visual evaluation experiments.
Regarding our method for measuring physical values, we prepared 127 samples of flat objects
which consisted of two materials—resin and metal plating. About half of these samples weretransparent or translucent. For those samples, we measured five kinds of measurements:‘Gloss’, ‘HAZE’, ‘Distinctness of Image’ (DOI), ‘Transmittance’, and a luminance image, whichwere determined by referring to the classification of perceptual gloss (Hunter, 1937). ‘Gloss’
represented the intensity of specular light. We followed the ISO standard. ‘Gloss’ wasmeasured by three angles (20°, 60°, 85°). ‘HAZE’ represented an optical effect caused by the
microscopic textures or residue on a surface. ‘DOI’ represented a quantification of thedeviation of the direction of light propagation from the regular direction by scattering duringtransmission or reflection. Their three physical values were measured by a goniophotometer(KONICA MINOLTA, Rhopoint IQ-S). ‘Transmittance’ was measured at three points on thefront and back of the sample by a spectrophotometer (KONICA MINOLTA, CM -5). The
luminance images were measured as HDR images using a digital camera (Canon EOS 5D
Mark IV) in the same setting as the visual evaluation experiment. The same threemeasurement angles used in the ‘Gloss’ measurement were utilized. We calculated the grey
level co-occurrence matrix (GLCM) from the luminance image and derived five feature values:‘Contrast’, ‘Dissimilarity’, ‘Homogeneity’, ‘Angular Second Moment’ and ‘Entropy’.
Regarding our visual evaluation experiment of perceptual gloss, ten men and women in their
twenties participated. In the experiment, observers evaluated perceptual gloss for samples ata viewing distance of 40 cm. In addition, the distance between the illumination and the sample
was 40 cm, and the experiment was conducted by changing the illumination to the same three
angles used in the ‘Gloss’ measurement. We used the magnitude estimation as an evaluation
method. Magnitude estimation is a psychophysical method in which observers judge andassign numerical estimates to the perceived gloss of a stimulus. An experimenter presented astandard stimulus and assigned 100 as an estimate. For a completely non -gloss sample, 0
was assigned as an estimate. If the observer thought the new stimulus was twice as intense
as the standard, 200 was assigned as an estimate. There was no upper limit to the evaluation
value. The evaluated data were analysed and modelled after removing outliers through theSmirnov-Grabs test. Modelling was performed by multiple regression analysis using allmeasured values and perceptual gloss obtained by evaluation experiments. To evaluate themodel, coefficient of determination and MSE were used. MSE was obtained cross -validation.

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3. Results
The results of our modelling through multiple regression analysis showed that the mostaccurate model was built when the samples were classified into a group with 0%transmittance and a group of otherwise. The coefficient of determination was about 0.7 at 20°,
about 0.7 at 60°, and about 0.6 at 85°.In addition, the perceptual gloss could be estimatedwithin about 1σ of the standard deviation of evaluation values between observers. In themultiple regression analysis, the variables that were sta tistically significant differed dependingon the angle and group, but they worked effectively in the order of ‘Gloss’, ‘Contrast’, and‘HAZE’. Since the coefficient of determination was 0.1 in the simple regression using only
‘Gloss’, a highly accurate estimation was possible by combining multiple physical quantities.
4. Conclusions
In this study, we measured the various physical values of flat objects and modelled for theperceptual gloss obtained by psychophysical experiments using multiple regression a nalysis.
We found that the coefficient of determination was about 0.6 to 0.7, and it was possible toestimate the perceptual gloss from the physically measured values within the standard
deviation of 1σ between observers’ evaluation. Specifically, by group ing transmittance values,
highly accurate modelling became possible. In this experiment, a grey sample was used to
avoid the influence of colours. Further research is needed to investigate the effect of colours
on perceptual gloss.

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OP11
EFFECT OF LIGHT SOURCE DISTANCE ON THE DISCRIMINATION AND GLOSSPERCEPTION OF PAPER
Zhu, X.Y., Inoue, S., Sato, H., Mizokami, Y.
Chiba University, Chiba, JAPAN
caga1015@chiba-u.jp

Abstract
1. Motivation
Colour and texture information that our eyes receive varies significan tly since the lightentering the eye changes depending on physical factors such as surface materials andlighting conditions. Therefore, our complex visual perception can be affected by various
physical characteristics. However, we have perceptual constanc y for various aspects of visionsuch as size, shape, etc. Colour constancy is a well-known ability to perceive an object’s
invariant colours, even if the light source changes. Besides colour, gloss is also an importantvisual property of objects. We perceive gloss mainly based on specular highlights’appearance, which is determined by complex interactions between physical properties ofilluminance, surface texture, shape, etc. The reflection of light on materials also changes
depending on the viewing conditions. However, it was suggested that humans could estimate
the original gloss of the materials. It is called gloss constancy. Previous research about theeffect of light source distance on the gloss unevenness of paper showed that a gloss area
becomes wider when the point light source distance increased. It is unknown yet how thisphysical change influences our recognition and visual gloss perception of paper. Here, w einvestigate the discrimination of paper type and gloss constancy under the light source
distance changes.
2. Methods
To investigate the influence of light source distance on the recognition of paper and gloss
constancy, we asked observers to evaluate the discrimination of paper type and gloss
appearance. We built two same sets of lighting equipment side by side. The line light source
aperture was 0.4 mm in width, and the length was 120 mm. We prepared three kinds ofprinting paper samples (7 cm x 7 cm) and three distances of light sources (125 mm, 250 mm,
500 mm) on a 45-degrees line. Papers used for the experiment had different glossiness levels,
labeled as MG (mid-glossiness), HG (high-glossiness), and SHG (super-high-glossiness).
Each paper’s gloss area became wider when the light source distance increased. We set theilluminance of each sample to 1250 lx at the 250 mm-distance condition. The illuminancechanged when moving the light closer or further. In the experiment, observers alternately
viewed two samples of the same or different paper types on each side. The viewing distancefrom each sample was 250 mm. Observers used an observation box to limit the visual field toeach sample’s surface and keep the viewing angle to the 45-degrees. They could move theobservation box left and right to observe the samples repeatedly until they decided the ir
judgment. A sample pair was chosen randomly out of six possible pairs. Also, the combinationof the right and left light source distance was set randomly. T o examine the effect of the
distance of light on gloss perception, we asked observers to evaluate perceptual scales ofgloss from 1-10 points. To find the influence of perceived gloss on the discrimination of paper
types, we asked observers to answer whether two samples appeared the same paper type byeither yes or no forced choice.
3. Results
Our results showed that when observers viewed the same type of paper, the identification of
paper types was better under light source at the same distance. However, when the distanceof the two light sources became different, the responses were not stable. Some observers
correctly recognized the same type of paper, even at different light source dist ances. Whenobservers viewed different paper types, it was easier to discriminate 125 mm -SHG with MG

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and HG under different light source distances. Their widths of gloss areas were also obviously
different, implying the interaction between gloss areas and material surface recognition. We
hardly found gloss constancy across the different light source distances. The gloss perception
was affected by the point light source distance. However, the viewing field was restricted tothe sample area, and the illuminance changed as changing the light source distances. We
need further investigation to consider the possible effect of viewing conditions.
4. Conclusions
We examined whether the stable recognition of paper and gloss constancy occurred whenobserving papers with different glossiness levels at the different light source distances. Our
results showed that the identification of paper types was better under light source at the same
distance. We hardly found the gloss constancy across the light source distance changed. Thissuggests that the human gloss perception could be largely affected by the point light source
distance, at least under a restricted viewing condition. We need further investigation on therole of gloss in the recognition mechanism of the texture of materials.

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OP12
COLOUR PERCEPTION OF LED POINT LIGHT SOURCES IN SCOTOPIC VISION
Tanaka, M., Ogawa, R., Horiuchi, T.
JAPANmidori@chiba-u.jp

Abstract
1. Motivation, specific objective
In recent years, displays such as the OLED have been developed, and the luminance,
contrast, and pixel miniaturization of displays are improving. This has made it possible toreproduce images that could have not been perceived in the pas t. Therefore, it is important toclarify the effects of image reproduction using these new displays on colour perception andpsychology. The purpose of this paper is to experimentally investigate the colour perceptionof a small visual field in scotopic vision by focusing on fine and high-contrast image
reproduction.
In the field of vision science, if stimuli are made sufficiently small, colour -normal individuals
report a loss in hue perception like tritanopia. This effect is referred to as small field trit anopia.
Thus far, small field tritanopia has mainly been studied regarding object colour using colour
patches and light source colour using narrow-band illuminants; however, wideband lightsource colours such as the LED have not been investigated. Furtherm ore, regarding the
scotopic vision targeted in this study, the interaction between small field tritanopia and therods working in scotopic vision has not been clarified. This paper provides new insights into
small-field colour perception using a new display device.
2. Methods
We performed a colour matching experiment using LED point light sources in scotopic vision.
In the experiment, a test stimulus and a reference stimulus were presented side by side.
Observers freely adjusted the hue, saturation, and li ghtness of the test stimulus to match thecolour of the reference stimulus. The test stimulus was represented on a LED display (LEDDS20M12K01) that uses an array of RGB LEDs as pixels. The reference stimulus was
spectrally reproduced as blackbody radiation using a spectral tunable LED (THOUSLITE
LEDCube). Both stimuli were presented through a small circular hole. Three colours on theblackbody radiation trajectory with colour temperatures of 3500K, 5400K, and 11600K wereused as reference colours. Small circular holes subtending visual angles of 6’ and 10.8’ foreach stimulus, confirmed as inducing small field tritanopia in previous studies, were used. For
each reference stimulus, each observer performed colour matching three times. Ten men andwomen with normal colour vision participated in the experiment with the visual angle of 6’, andfour men and women participated in the experiment with the visual angle of 10.8’. The
matched colour on the LED display was measured with a spectroradiometer (KONICAMINOLTA CS-2000) for all trials of all observers.
3. Results
We plotted the matching results on a CIE xy chromaticity diagram of each reference colourand calculated 95% confidence ellipses to consider the tendency of the distribution. The
5400K and 11600K stimuli of the visual angle 6’ were distributed diagonally from the lower left
to the upper right of each reference stimulus in the xy chromaticity diagram. The 3500K
stimulus was distributed in a nearly circular shape around the reference stimulus. These
distributions were different from MacAdam's colour discrimination ellipse. We adopted aprincipal component analysis on those distributions and compared them with the inclinationsof the confusion lines of tritanopia. The inclination of the first principal com ponent axis of5400K and 11600K was similar to the inclination of the confusion colour line of tritanopia andtended to be similar to that of small field tritanopia. In contrast, the sizes of the first and43

CIE 2021 - Abstract Booklet

second principal components of 3500K were almost the same, and there was no tendency forsmall field tritanopia.
For the results concerning the visual angle of 10.8’, we similarly plotted the matching results
on an xy chromaticity diagram and calculated 95% confidence ellipses. The ellipses were
smaller and closer to a circle than those for the visual angle 6’. Thus, the effect of the small
field tritanopia on the distribution seems to be reduced. It was shown that the colour
perception of small field stimuli became more confused as the stimulus size decre ased.
Therefore, the colour perception might be stabilized by expanding the stimulus size. The
distribution tendency for the visual angle 10.8’ was the same as for the visual angle 6’. The
5400K and 11600K stimuli were distributed diagonally to the referen ce stimuli. Comparing theinclination of the principal component axis with the confusion colour line of tritanopia, theresults showed the influence of small field tritanopia. However, this tendency was not seen forthe 3500K stimulus.
For both visual angles, the matching results showed that y values were smaller than thereference stimuli for all three stimuli. This means that observers tended to perceive green
strongly. It is necessary to analyse whether this tendency of perceiving green more strongly is
due to human perception or the display characteristics.
4. Conclusions
In this paper, we analysed colour perception of LED point light sources with a wide -band
spectral distribution by conducting colour matching experiments in scotopic vision. In thematching results for both viewing angles of 6' and 10.8', the distribution was similar to thoseof tritanopia for the 5400K and 11600K stimuli, suggesting colour discrimination with thecharacteristics of small field tritanopia. For the 3500K stimulus, the res ult did not show theinfluence of small field tritanopia. For the larger viewing angle, more stable and less confusedmatching results were obtained. In addition, the observers perceived green strongly for apoint light source in scotopic vision. It is necessary to analyse whether this is due to thecharacteristics of the LED light source or factors related to human perception.
In particular, the colour matching distribution of the 11600K stimulus varied widely. In our
analysis, we did not take differences in brightness perception between individuals into
account. According to the Helmholtz-Colelauche effect, individual differences in brightness
perception affect saturation perception. Thus, it is necessary to consider differences inperception between individuals in the future.

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Session OS4
D2 – Measurement theory
Monday, September 27, 17:30–19:00

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OP13
AN OVERVIEW OF IMPORTANT FACTORS TO CONSIDER WHEN CALIBRATING LEDS
IN PHOTOMETRY WITH DIFFERENT DETECTORS
Gerloff, T.1, Ulm, L.1, Sperfeld, P.1 and Sperling, A.1
1
PTB, Braunschweig, GERMANY
thorsten.gerloff@ptb.de

Abstract
1. Motivation, specific objective
LED-based lighting products are the fastest developing light sources on the general lighting
market. These include not only white light sources, but als o coloured light sources. Due to thespectral and geometric properties of LEDs, SI-traceable calibrations are much more difficult
than those of traditional incandescent or fluorescent light sources.
Furthermore, different detector types can be used when calibrating LEDs. These include
classic photometers, radiometers, spectroradiometers but also imaging systems such as
ILMDs. Each of these measuring devices has its specific advantages and disadvantages.
In this paper, traceable calibrations on 9 coloured a nd 9 white LEDs are discussed. Various
array spectroradiometers, photometers, radiometers and a double monochromator were used
for this purpose. Each of these measuring instruments is discussed in terms of its suitability
for measuring different physical quantities (e.g. array spectrometer for measuring illuminance).
Furthermore, important correction factors, possible correlations and uncertainty contributions
are discussed.
2. Methods
For a meaningful comparison of different measuring devices, a sufficient luminous intensity
and a sufficiently large distance are necessary so that the dominant uncertainty contributions
come from the LED properties and not from bad S/N-ratio, distance measurements or the like.
Therefore, 18 special circuit boards each equipped with 32 LEDs of the same type were
produced. These are 9 coloured LED types with peak wavelengths between 440 nm and
730 nm. Furthermore, there are 9 white LED types with CCTs between 2,350 K and 10,000 K.
The LEDs are mounted one after the other on a separate holder with active temperature
control to keep the light emission stable.
The following detectors were used for the measurements:-

different radiometer heads-

different photometer heads-

different spectroradiometer models (with different entrance optic s)-

1 double monochromator

To make the results comparable, all devices were used in the same measurement geometry
and calibrated with the same methods and reference standards.
3. Results
Part one:The spectral mismatch of photometers with V(  ) filters sometimes leads to large deviations in
the measurement. By correcting the mismatch with knowledge of the relative spectral
distribution of the LED and the spectral sensitivity of the photometer, the deviations can be

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corrected. Since photometers and spectroradiometers must be used for this purpose, manyusers refrain from using photometers and perform all measurements with spectroradiometers.
In the presentation, the results for illuminance measurements with a single photometer, asingle array spectroradiometer and the combination of both measuring instruments arepresented. Special emphasis will be placed on the respective measurement uncertainty
budgets. Only when all uncertainty contributions are correctly determined is there no longer
any significant difference between the individual measurement results. Moreover, determining
correlations within the measurement chain is a prerequisite for providing reliable uncertainties
and trustworthy results.
Part two:
Another important aspect for calibrations is the speed in which a single measurement iscompleted. Spectrally integrating detectors such as photometers work very quickly andreliably even at very low illuminances. Therefore, such detectors are often used ongoniophotometers. However, the use of spectroradiometers is also useful here to be able todetermine the total spectral radiant flux of light sources.
In the lecture, the results from many individual measurements with photometers, radiometersand spectroradiometers at different illuminance values are presented. It will be shown whichmeasuring instruments make sense to use for which applications and what do you have to pay
attention to.
4. Conclusions
In the lecture, a summary of different measurement methods for LED calibrations will be give n.
The data is based on a large number of individual measurements with associatedmeasurement uncertainties.
This overview can be used by users to find suitable measurement methods for their LED
applications and to identify important measurement uncertaint y contributions.

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OP14
DEGREE OF EQUIVALENCE OF TRISTIMULUS VALUES OF LEDS UNDERCONSIDERATION OF MEASUREMENT UNCERTAINTY AND CORRELATION
1Ruggaber, B. 1, Krüger, U.1, Blattner, P.2 ,Gerloff, T.3
TechnoTeam Bildverarbeitung GmbH, Ilmenau, GERMANY
2METAS, Bern, SWITZERLAND
3
PTB, Braunschweig, GERMANY
benjamin.ruggaber@technoteam.de

Abstract
1. Motivation, specific objective
Measuring the tristimulus values of LED-based light sources can be considered asmeasurement problem with a multidimensional output quantity. Thus a complete statement of
measurement uncertainty of tristimulus values includes a declaration of the correlation
between the individual coordinates. Furthermore, by calculating tristimul us values,
correlations in-between the tristimulus values are introduced. However, these correlations arenaturally taken into account when using the Monte-Carlo approach for measurement
uncertainty evaluation.
The measurement result is usually stated as a two-dimensional chromaticity coordinate (x,y)
and a one-dimensional luminance value L. The associated measurement uncertainties consistof u(x), u(y) their correlation coefficient, ρ x,y , and u(L). In both cases, normal distributions are
assumed, where the chromaticity coordinates cover an ellipsoid shaped area in the xy -plane.
For the purpose of measurement comparisons, it is necessary to evaluate the degree of
equivalence of two different measurement results. In the literature, one can find standard
methods to compare measurement results even for non-scalar measurands taking thecorrelations into account. However, there are some aspects one has to take care of whileworking with the tristimulus values of LEDs.


The shape of the coverage region of the chromaticity coordinates ( x,y) is very different
for blue, green, red and white LEDs. This will result in different methods for thecomparison of the measurement results.

Especially for red LEDs, the chromaticity coordinates are fully anti -correlated, having acorrelation coefficient of -1, which means that the standard methods for measurementcomparisons are not applicable.



The measurement uncertainty area for green LEDs may be non-ellipsoid shaped forlarger uncertainties u(x) and u(y). Therefore the approximation using the measurement
uncertainty for x and y and a correlation coefficient and the assumption of normal
distributions maybe not sufficient.

2. Methods
Starting with the general introduction to the concept of degree of equivalence in metrology for
scalar quantities the concept will be extended to multidimensional output quantities based onstandard methods known from literature.
The use of the standard methods for the comparison of tristimulus values is demonstrated onbehalf of measurement results for phosphor type white LEDs. Furthermore, the problems of
the standard methods will be demonstrated on behalf of coloured LEDs to highlight the
motivation for new methods.
To overcome the demonstrated problems for coloured LEDs caused by high correlations or
non-ellipsoid shaped uncertainty areas the following methods will be introduced:

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1) One dimensional approach: Full correlated or anti-correlated two dimensional quantities
can be reduced to one dimension.
2) Dominant wavelength approach: The chromaticity coordinates of coloured LEDs areusually very close to the spectral locus. They can be represented by the dominant
wavelength and thus the problem is reduced to a one-dimensional quantity. The luminanceis treated separately.
3) Three-dimensional approach: Extending the two-dimensional problem to a threedimensional one while evaluating not only X and Y but also the Z value.
4) Counting approach: Estimating the degree of equivalence counting out the overlapping
areas for non-ellipsoid shaped measurement uncertainty area based on the informationfrom original Monte Carlo simulations. While treating the luminance value separately or
counting in the 3D space.
3. Results
The application of the suggested methods will be demonstrated using LED-based luminancestandards of different colours including blue, green, red and whites, measured by two different
laboratories.
4. Conclusions
Depending on the colour of the LED source, different methods can be applie d:For white LEDs the standard approach, which includes the measurement uncertainty
and correlation between the coordinates is applicable. Ignoring the correlation could
lead to an overestimation of the degree of equivalence.

For coloured and usually high-saturated LEDs the dominant wavelength approach isapplicable.



For red LEDs, the coverage ellipses are degenerated to line segments as thechromaticity coordinates are fully anti-correlated. Comparing two quasi-parallel line
segments is difficult as the distance between the lines is mainly influenced by thespectral straylight (or straylight correction) of the spectral measurement devices.
Alternatively to the dominant wavelength approach the problem can be directlyreduced to a single chromaticity coordinate (x) and thus to a one-dimensional quantity.



For the evaluation of blue LEDs, the dominant wavelength approach should be used
but the standard approach is sometimes still applicable if the correlations are not too
high.



Comparing the results for green LEDs the comparison method depends on themeasurement uncertainty. For small uncertainties the dominant wavelength approach
can be used. For larger measurement uncertainties one gets more and more non ellipsoid shapes for the uncertainty areas and the counting approach needs to be used.

Note: For the three-dimensional approach and the counting approach the usual measurement
uncertainty statement using two measurement uncertainties u(x) and u(y) together with thecorrelation coefficient is not sufficient for the measurement comparison. In this case the labs
need to exchange more data.

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OP15
SPECTRAL MEASUREMENT AND CLASSIFICATION IN THE ERA OF BIG DATA
1

Webler, F.S.1, Andersen, M.1
Laboratory of Integrated Performance in Design (LIPID), School of Architecture , Civil andEnvironmental Engineering (ENAC), Ecole polytechnique fédérale de Lausanne (EPFL),
Lausanne, SWITZERLAND
forrest.webler@epfl.ch

Abstract
1. Motivation, specific objective
The measurement and classification of light is essential across many scie ntific disciplines.
Devices used to measure light range from the highly precise scanning spectroradiometers to
the more practical compact multichannel filter-array type imaging sensors and the ubiquitous
RGB pixel. Historically, devices have been character ized by their ability to resolve detail
directly; specifically, as a property of their optical properties and electronic design. In otherwords, a RGB camera is not a spectrometer because it is unable to capture the entire
spectrum of light. That said, there have been numerous successful efforts to reconstructspectrum from RGB thereby enabling the humble pixel with the power of software. While
RGB-to-spectrum has historically been limited to natural scenes and other edge cases understrict constraints, advances in deep learning, and information theory more broadly, have shedlight on the vast amount of redundancy contained within data collected in the natural world
including light. Exploiting redundancies found via machine learning methods has huge
implications on measurement and classification of data in general and is quickly ushering in a
new data-driven era whereby any datum can be refined to its unique identifying properties or‘intrinsic’ representation in some latent (i.e., compressed) space.
We decided to investigate how modern machine learning methods could map highdimensional spectra data to a low-dimensional feature space in theory and practice bysimulating different encoders. For this task, we compiled a diverse set of broadband andnarrowband (natural and artificial) signals by aggregating multiple online datasets into alibrary of 1000 spectra. We selected spectra with vastly different distributions fromexperimental monochromatic sources and neodymium bulbs to theoretical black bodyradiators. Understanding the intrinsic dimension of any datum is important because thefeatures expressed in this representation can be used to exploit regularities and make tasks
like data compression, measurement and classification more efficient. Lossless datacompression has for years used dimension reduction methods like principal component
analysis (PCA) and new compact spectrometers have even been designed using methods incompressive sensing where only the most informative frequencies of the spectrum aremeasured. We hope that our analysis can help inform how and when low -dimensional
representation of spectra is useful in practice for designing compact sensors as well as forlossy data compression and robust classification.
2. Methods
Our primary objective was to compare different matrix decomposition methods and methods
from deep learning to find an encoder that balances accuracy (i.e., reconstruction fidelity) andcomplexity (compressed file size). The goal was to use real and theoretical encoding
functions to determine the feasibility of different encoders as well as estimate the theoreticalcompression limit or ‘intrinsic dimension’ for diverse classes of spectral signals. Practically,
we imported spectral data from open-access online sources into a large array in MATLAB.
The data were then cleaned and processed using conventional interpolation methods tonormalize variation among datasets. We then applied various decomposition methods to thespectra before applying a reconstruction algorithm. Cross -validated error was reported as ameasure of total information loss.

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3. Results
The results support our intuition that signal complexity is the biggest constraint oncompressibility. However, when it comes to designing an efficient encoder, some complex
signals benefit from characteristic emission peaks which make them easier to classify. We
measured redundancy in terms of the number of points needed to reconstruct the spectrumwith an RMSE < 0.05. Interestingly, we saw a saturating effect between n = 8 and n > 27
(depending on bandwidth) indicating that regardless of the type of spectrum there is an upper
limit in terms of the amount of information required to effectively encode it and that this limit
occurs in the sub-Nyquist regime implying that the machine learning techniques are effective
in finding latent representations in signal space.
4. Conclusions
Understanding the intrinsic dimension of spectral distributions is important in both theory andpractice. In theory it is important to separate redundant and ess ential information forclassification and formal definition. In practice, there are numerous advantages for identifying
redundant information. Many applications require reducing size, weight, power, and cost
(SaWP-C) that can only be done by collecting the lowest informative representation of thesignal (i.e., ‘latent dimension’). In this era of big data, it is important that we continue tounderstand how machine learning can streamline data representation and inform ourunderstanding of the fundamental structure of said data. Thus, the systems and methods used
to describe data are continuously updated to reflect advances in technology andunderstanding.

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Session OS5
D3/D6 – Integrative lighting (2)Monday, September 27, 19:15–20:45

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OP16
TOWARDS A FRAMEWORK FOR LIGHT-DOSIMETRY STUDIES: METHODOLOGICALCONSIDERATIONS
Hartmeyer, S.L., Andersen, M.
Laboratory for Integrated Performance in Design, School of Architecture, Civil andEnvironmental Engineering (ENAC), Ecole Polytechnique Fédérale de Lausanne (EPFL ),Lausanne, SWITZERLAND
steffen.hartmeyer@epfl.ch

Abstract
1. Motivation, specific objective
Decades of research have shown that light has behavioral and physiological effects unrelated
to human vision, mediated by a dedicated neural pathway. Much of what is known about thesenon-visual effects of light has been established by extensive laboratory research, indicatingthat responses are dependent on the spectrum, spatial distribution, intensity, duration, timing,
temporal pattern, and prior history of light exposure. While dose-response curves have beendeveloped under controlled conditions, knowledge is still limited in order to predict the effects
of light under real-life conditions. As a consequence, guidelines and recommendations for
personal light exposure and lighting design are approximations at best.
One potential approach to arrive at a more consolidated understanding of the non -visual
effects of light is to complement bottom-up laboratory research with top-down field research,
extracting consistencies across datasets of real-life measurements and reverse-engineer
dose-response curves and other effectivity metrics of interest. In order for such an approach
to be successful, standardized protocols for measuring and quantifying personal light
exposure (PLE) data are urgently needed.
To this end we performed a comprehensive review of dosimetry field studies published to date,aiming to lay the groundwork for a consensus framework for light -dosimetry studies that takes
into account each step in the process, from measuring, to calibrating, to quantifying PLE data.
Here we present an extract of this work, focusing specifically on methodologicalconsiderations in dosimetry studies.
2. Methods
In total, more than 100 studies were identified from systematic da tabase search. Studies were
included if PLE measurements were collected, quantified and included in the analysis.
Intervention studies and studies of measures unrelated to the non -visual system were only
included if they added novel metrics or dosimetry procedures to the review. Studies focusing
on dosimetry metrics alone were not included in the set of PLE studies but are part of the
discussion literature.
Studies were analyzed and discussed in terms of quantification and transformation methods,
as well as dosimetry setup, in order to identify methodological considerations to be includedin the framework and highlight points that need to be addressed and clarified in future studies
before such a framework could be fully established.
3. Results
In terms of dosimetry setup, a large variety of dosimetry devices was used across studies,dominated by wrist-worn actigraphy devices with integrated photodiodes. Only relatively few
studies used dedicated light-dosimetry devices worn at eye-level or the chest, despite
evidence pointing towards increased measurement accuracy at these locations. Likely
reasons are participant compliance and equipment limitations. Sampling rates varied but were
centered around 1min. Sampling rates may be device-dependent but should be considered fora trade-off in measurement resolution and battery life. Calibration was performed only by a

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minority of studies, while most studies do not report whether or how devices were calibrated,
despite evidence for large inter- and intra-device variability.
Regarding data processing, more than half of the studies either did not log -transform ortransformed the data after aggregation, whereas the rest transformed the raw data. The orderof transformation can result in substantial differences, especially when aggregating overlarger time intervals, and physiological mechanisms point towards log -transforming raw data.
Alternatively, smoothing may be used to stabilize the data’s variance, however this technique
has only been used by very few studies.
Studies used a large variety of metrics to characterize PLE data in terms of the spectrum,
intensity, duration, timing, and prior history. However, often only a narrow selection of metrics
was used, with a tendency towards simpler and less robust metrics. Simila rly, very few
studies report spectrally weighted quantities other than photopic illuminance, despite
evidence for the insufficiency of photopic illuminance to describe non -visual effectiveness.
Additionally, beyond the set of dosimetry field studies, only very few studies were identified
that specifically discuss dose metrics and methods for analyzing PLE data.
4. Conclusions
Within the context of a larger review effort, this paper focuses on providing a systematic analysis ofmethodologies in light-dosimetry studies. As a large variability in the studies’ methodologies isobserved, it provides the opportunity to form a solid basis for the development of a framework for lightdosimetry studies. We propose methodological considerations that should be included in such aframework and can already be used by future studies. Furthermore, we highlight important points thatshould be specifically addressed in future research in order to ensure compatibility between datasetsfrom different dosimetry studies, such as agreement on measurement and calibration procedures. Notpresented here is a discussion of the broad repertoire of dose metrics and how they can be related tothe study of physiological and behavioral responses to light, which will be included in a forthcoming
complete review. Taken together, this review effort underlines the importance of a systematic
approach to light-dosimetry in order to harness all the power of real-life light exposure studies.

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OP17
NEW ANTIMICROBIAL STRATEGIE USING COMPOSITIONS WITH PHOTOCATALYTIC
PROPERTIES
Bucuresteanu, R.C. 1; Ditu, L.M.1; Husch, M.2; Raditoiu V. 3; Marcu, C.4; Ionita, M.5; Mihaiescu, G.1;
University of Bucharest, Faculty of Biology, Microbiology Department, Bucharest, ROMANIA ,2
Bucharest Technical University of Civil Engineering, Faculty of Building Services
Engineering, ROMANIA, 3 National Institute for Research & Development in Chemistry andPetrochemistry, Bucharest, ROMANIA, 4 Dâmboviţa County Emergency Hospital; Targoviste,
ROMANIA, 5 Politehnica University, Faculty of Applied Chemistry and Materials Science,
Bucharest, ROMANIA

1

1. Motivation
During 2020, the coronavirus COVID-19 pandemic generated a health crisis, emphasizing theneed to ensure clean spaces and surfaces that allow to develop activities in sanitary safety
conditions. One of the methods for limiting the virus transmission was the use of ultraviolet
radiation (UVR), which generated a huge demand for devices with UV-C lamps. C.I.E. itself
issued a statement position drawing attention, with professional arguments, on the benefits
but also the risks generated by UVR. On the other hand, with a much smaller scale and onlyat the level of the scientific community, some communications have brought to attention thebenefits of radiation from the visible spectrum, generating photocatalytic reactions of somecompounds with disinfectant properties.
Starting from the known action of light-activated antimicrobial agents (LAAAs), a new conceptof antimicrobial and antiviral protection was sought by developing coatings with self disinfecting properties generated in the presence of light. The principle is the activation withlight from the entire visible spectrum of a new photocata lytic pigment model based on doped
semiconductor metal oxides, which leads to the occurrence of chemical reactions, generating
toxic singlet oxygen for bacteria and viruses. Because the reaction is producing in visible light(VIS) area and not only in the UVA area, the new composition provides antimicrobial
protection of surfaces, protection that is constant throughout the day under the action ofsunlight and provided at night under the action of artificial lighting inside. The majoradvantage is that the agent that generates the active antimicrobial reaction is not consumed
during the coating life and it provides constant protection.
2. Method
The antimicrobial effect of photocatalytic reactions initiated by semiconductor metal oxides
such as TiO 2 has long been known. The disadvantage is that they are excited only in UVA.
The new method has developed a doped industrial TiO 2 model that complies with theprovisions of ISO 591-1: 2000 (Titanium dioxide pigments for paints - Part 1: Specifications
and test methods) and ISO 18451-1: 2019 (Pigments, dyestuffs and extenders - Terminology Part 1: General terms) and which has action in the visible spectrum.
The pigment was used to create a paint with antibacterial and antiviral properties. Samples ofthis paint were subjected to tests on photocatalytic activity and tests on antimicrobial andantiviral activity. For determination of the photocatalytic activity, a method developed basedon the standard DIN 52980:2008-10 “Photocatalytic activity of surfaces - Determination ofphotocatalytic activity by degradation of methylene blue” was used, respectively ISO 10678 2010 The determination of photocatalytic activity of surfaces in an aqueous medium bydegradation of methylene blue. The antimicrobial "in vitro" tests were performed in theMicrobiology Department of the Faculty of Biology (University of Bucharest) and " in situ" atthe Palliative Care Department at the Dâmboviţa Emergency Hospital, Romania. In vitro tests
were also performed at two independent institutes: ICECHIM ( National Institute for Research& Development in Chemistry and Petrochemistry) in Romania and J.S. HAMILTON subsidiaryfrom Poland, in different conditions: under the light and under the UV -A, for several types ofpathogens.

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3. Results
It was found that the photocatalytic antimicrobial paint sample shows photocatalytic activity
both in irradiation exclusively with light from the near UV area, and in irradiation exclusively
with light from the visible spectrum, as follows:- when irradiated with light from the near ultraviolet range (300 -400 nm), manifested by thediscoloration of an aqueous solution of Methylene Blue of 20 mg/l, with an average specificphotocatalytic activity PMB = 3.15 x 10 5 mol/m 2 ;- when irradiated with light from the visible range (400-800 nm), manifested by thediscoloration of an aqueous solution of Methylene Blue of 20 mg/l, with an average specificphotocatalytic activity PMB = 0.46 x 10 5 mol/m 2 .
Tests performed according to EN 1650: 2008 + A1: 2013 (Chemical disinfectants andantiseptics - Quantitative suspension test for the evaluation of fungicidal activity of chemical
disinfectants and antiseptics used in food, industrial, domestic and institutional areas - Test
method and requirements) have demonstrated that the sample shows microbicide activity on
the Aspergillus brasiliensis CECT-2574 (ATCC-16404) and Candida albicans CECT-1394(ATCC 10231).
Tests performed according to EN 1276 (Evaluation of chemical disinfectant or antiseptic forbactericidal activity) have demonstrated that the sample shows bactericidal activity on the
Pseudomonas aeruginosa CECT-116 (ATCC-15442) Escherichia coli CECT-405 (ATCC 10536)
Staphylococcus aureus CECT-239 ( ATCC-6538) and Enterococcus hirae CECT-4081 (ATCC10541).
According to ISO 27447: 2019 (Fine ceramics - advanced ceramic materials, advanced
technical ceramic materials - Test methods for the antiviral activity of semiconductor
photocatalytic materials) when irradiated with UV-A (315-400 nm wavelength), it was foundthat the Virucid percentage obtained for Coronavirus 229E (ATCC VR-740) was ≥ 78.01%.
The in situ antimicrobial tests were performed in two type of areas, during 2019 -2020: 2
painted hospital wards and 2 unpainted hospital ward. The total bacterial load of indoor air in
the two types of in hospital wards was monitored. There was a significant decrease in the
total number of microorganisms in the painted rooms, from 79 CFU/m 3 in 2019 to 0 CFU/m 3 in
2020, compared to the unpainted rooms in which the total number of microorganism remained
relatively constant, from 315 CFU/m 3 in 2019 to 236 CFU/m 3 in 2020.
4. Conclusions
Light-activated antimicrobial agents (LAAAs) act by generating reactive oxygen species withaction on multiple targets in microbial and virus pathogens. Photocatalytic coatings areproving to be promising for reducing the microbial load in medical facilities. The disinfection
process does not affect patients or medical staff, it can be done in their presence and has acontinuous, controllable effect. The field of application can be success fully extended to theadministration, education, food industry, transport. The major benefit of the new coating isthat it does not allow the induction of the resistance phenomenon and implicitly neither theselection of resistant cells.

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OP18
THE LIGHT-DOSIMETER – A NEW DEVICE TO HELP ADVANCE RESEARCH ON THE
NON-VISUAL RESPONSES TO LIGHT
1Stampfli, J.R.1; Schrader, B.1
Lucerne School of Engineering and Architecture, Horw, SWITZERLAND
janine.stampfli@hslu.ch

Abstract
1. Motivation, specific objective
Light triggers visual and non-visual responses and is closely linked to our health andwellbeing. While the visual responses to light are well known, research in the field of non visual responses is still in its infancy. Research in this field has become more p ressing, as themodern human being spends 90% of its time indoors, where light levels are much lower thanin the outdoors setting, daylight is filtered through window glass and artificial light sources
have different spectral compositions than daylight. Furthermore, artificial light, including lightfrom computer monitors, extends the “productive hours” to a period during which the humanbody is meant to rest in the dark. This can lead to a disturbance in the hormonal household
and consequently to a misalignment of the inner clock known as social jetlag.
A holistic understanding of the long-term exposure to light is needed to advance the researchof the non-visual responses to light. To collect such data a mobile measuring device, i.e. awearable, recording a test person’s light exposure, i.e. its amount and its spectral distribution,is required. However, the currently available devices have certain shortcomings such as thelight exposure being measured at the wrist, inaccurate metrics being used and no spe ctral
information or “raw data” being provided. The project’s deliverables, i.e. the light -dosimeters,
shall close that gap.
2. Methods
The light-dosimeter is an enhancement of a previously developed device by a team from
Lucerne School of Engineering and Architecture. Not only does the new device use a better
light sensor, it also comes with a custom-made software, which provides researchers with therecorded data in a csv-file and a pdf report. Furthermore, the light exposure is no longer
measured at the chest, but in the vicinity of the eye, i.e. the corneal plane. In addition to acasing containing the electronics, a fixture was designed, so that the device can easily beattached to and removed from a spectacle frame. And lastly, the latest internationa lly
commended metrics are used, i.e. those from CIE S 026:2018 “CIE System for Metrology of
Optical Radiation for ipRGC-Influenced Responses to Light”, in addition to the commonly usedmetrics (e.g. illuminance and correlated colour temperature and Duv). H owever, the data canbe used to specify other spectral sensitivity functions, if required.
3. Results
The light-dosimeter is a small (58 x 20.6 x 16 mm), low weight (27 g) device. It covers the
spectral range between 380 nm and 780 nm and its intensity range is 5 lx to more than
100k lx. It takes measurements every 10 seconds, its battery life is approx. 7 days and it canstore data from approx. 300 days. It has an optical diffusor, i.e. a cosine corrector, so that itcollects signals from a 180° field of view. Geometric and spectral tests conducted at the Swiss
Federal Institute of Metrology (METAS) in early 2021 showed good results. Initial tests in lab
and field settings are about to begin. Their findings will be available in early summer, so thatthey can be presented at the conference.
4. Conclusions
The team is confident that the light-dosimeters will enable the research community to advancethe current understanding between an individual’s light exposure and its physiologicalresponses. The recorded data from individuals of different ages, in different settings, from57

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urban and rural areas, from a range of occupations and at different times of the year will inturn help define recommendations of a “healthy light hygiene” in modern society, including theimportant role of daylight.

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OP19
LUOX: NOVEL OPEN-ACCESS AND OPEN-SOURCE WEB PLATFORM FOR
CALCULATING AND SHARING PHYSIOLOGICALLY RELEVANT QUANTITIES FOR
LIGHT AND LIGHTING
Spitschan, M.1, 2, 3, 4
Department of Experimental Psychology, University of Oxf ord, Oxford, UNITED KINGDOM, 2
Sleep and Circadian Neuroscience Institute (SCNi), University of Oxford, UNITED KINGDOM,
3Centre for Chronobiology, Psychiatric Hospital of the University of Basel (UPK), Basel,
SWITZERLAND, 4 Transfaculty Research Platform Molecular and Cognitive Neurosciences,
University of Basel, Basel, SWITZERLAND
manuel.spitschan@psy.ox.ac.uk

1

Abstract
1. Motivation, specific objective
Light exposure has a profound impact on human physiology and behaviour. For example, light
exposure at the wrong time can disrupt our circadian rhythms and acutely suppress the
production of melatonin. In turn, appropriately timed light exposure can support circadianphotoentrainment. Beginning with the discovery that melatonin production is acutely
suppressed by bright light more than forty years ago, understanding which aspects of lightdrive the 'non-visual' responses to light remains a highly active research area, with animportant translational dimension and implications for "human -centric" or physiologicallyinspired architectural lighting design. In 2018, the International Commission on Illumination(CIE) standardized the spectral sensitivities for predicting the non -visual effects of a given
spectrum of light with respect to the activation of the five photoreceptor classes in the humanretina: the L, M and S cones, the rods, and the melanopsin -containing intrinsicallyphotosensitive retinal ganglion cells (ipRGCs).
2. Methods
Here, we describe a novel, lean, user-friendly, open-access and open-source web platform forcalculating quantities related to light implemented in JavaScript, HTML, CSS, React andchart.js. The platform, called luox, enables researchers and research users in chronobiology,
sleep research and adjacent field to turn spectral measurem ents into reportable quantities.
The luox code base, released under the GPL-3.0 License, is modular and therefore
extendable to other spectrum-derived quantities.
3. Resultsluox is fully functional and modular, enabling the incorporation of other spectral ly derived
quantities in the future. Validation of the currently implemented quantities by a CIE Task
Group is currently ongoing.
4. Conclusions
We present a novel, web-based platform for calculating quantities for light and lighting.

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Session OS6
D3 – Glare
Tuesday, September 28, 14:00–15:30

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OP20
DAYLIGHT GLARE PROBABILITY PREDICTION FOR AN OFFICE ROOM
Martin, S.1, Mentens, A. 1, Lataire, J. 1, Jacobs, V.A. 1.
1
Vrij Universiteit Brussel, Brussels, BELGIUM
1. Motivation, specific objective
In recent years, work practice has changed and as a result, humans are pushed to work more
and more behind a desk in an office or at home. This working style can account for around 40
hours a week or even more. To increase the productivity, a good working environment isneeded. This is why, when offices in buildings are designed, the working environment isconstructed carefully taking into account several factors. The daylight admittance of theworking office is one important factor that must be taken into account. In order to havesatisfactory user comfort in the designed room, the position of the windows and other daylight
inlets should be considered. Nowadays, with the shift towards smart buildings, it is possible toimplement smart shading devices that allow us to control the light captured by the humaneyes that may tend to be disturbing at different hours of the day. Hence, increasing daylightand decreasing artificial light will have a positive impact on energy consumption and visual
comfort. But one of the main issues with such a shading device is that it must be able toestimate when the observer perceives glare. This without directly asking this to the observer
or without the need to place a sensor in the direct vicinity of the observer’s head. Moreover,when implementing such strategies in real office spaces, such placement of sensors is
impractical. It would however make sense to use the pre-installed cameras in such offices.
Based on machine-learning techniques and a virtual model of an office, this paper rese arches
if the DGP at the user-level can be estimated by a DGP assessment of a downward -pointing
camera sensor that is placed near the ceiling of an office.
2. Methods
To do this, the DGP has been simulated for a year in the case of an observer sitting behi nd
his desk facing the window in a simple office room for only one person with an annual climate
file of Brussels. The simulation process uses the daylight simulation tool Diva. The latter
utilizes the Radiance calculation engine which is a well -known daylight simulation softwarethat applies backward ray-tracing to reach accurate results. Diva is coupled to the graphicalalgorithm editor Grasshopper for Rhinoceros 3D, which serves as an efficient way ofparametric modelling. The data gathered with this simulation are transferred to Matlab inorder to analyse it and build a model out of it. At first, the existence of some simple
correlation between the observer DGP and some parameters influencing it have been
investigated and then a model has been built with the help of AI (Artificial Intelligence) to link
the observer DGP and some of these parameters. To this end, several regression methods
have been compared such as neural networks and boosted trees with the Statistics andMachine Learning Toolbox * and the Deep Learning Toolbox †. To be able to control a Venetianblind, three different models have been considered: empty room without shading devices, aroom with a desk and a computer without shading device, an empty room with different
inclinations for the Venetian blinds.
3. Results
To build and validate the different models, independent data has been used depending on thecase. For example, in the case of the empty room without shading device, a data set
containing measurements for every hour from 10 am to 6 pm for the first and third week ofeach month in a year has been used for training and the validation has been performed on adataset containing the second week of each month. As results, the models have reached agood accuracy and have well estimated the DGP for most of the cases with an error smaller*†

https://www.mathworks.com/products/statistics.html
https://www.mathworks.com/products/deep-learning.html

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than five percent. Also, less than one percent of the validation dataset has been really
misclassified in terms of barely perceptible, perceptible and intolerable glare for all the cases.
Moreover, results show that the key indicators to estimate the observer’s DGP are the sun
direction and the DGP from the ceiling camera.
4. Conclusions
With these results it can be concluded that such a model is able to properly estimate the DGP
by using a sensor mounted to the ceiling. This research supports the development of aneffective control strategy of Venetian blinds for maximizing visual comfort whilst minimizing
energy consumption by artificial lighting. Further work will study a real implementation of sucha shading device. In a first time, some data could be acquired by taking pictures with acamera on the ceiling and one place at the observer view point to measure the DGP forvarious orientations of the blind and also in the case where the blinds are retracted. Fi nally,
the data acquired through simulation and experiments could be compared and by dividing theexperimental one into two independent datasets, a model can be built and its accuracy could
be compared to the one of the theoretical models.

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OP21
ON SENSITIVITY TO GLARE AND ITS RELATIONSHIP WITH MACULAR PIGMENT
1

Jain, S.1, Wienold, J.1, Andersen, M.1
École polytechnique fédérale de Lausanne – EPFL, SWITZERLAND

Abstract
1. Motivation, specific objective
Properly addressing glare risks in buildings is crucial towards achieving comfortable visualenvironments. It is, therefore, necessary to understand what causes or influences theperception of discomfort glare. Although several glare prediction models based on physicalquantities have been developed in the last two decades, current models are unable to capture
the large inter-individual variability that is observed in the perception of discomfort glare. If weassume that the tolerance towards discomfort glare does indeed vary among individuals, it
seems plausible that certain eye morphology parameters could at least in part explain thisvariability.
In this paper, we hypothesize that a specific ocular physiology characteristic, namely themacular pigment (MP) in the retina, could have an influence on glare se nsitivity, encouraged
by recent findings from the literature that have shown that high MP levels were indicative ofbetter visual performance than low MP levels. This study aims to determine whether aperson’s sensitivity to glare could be somehow correlated to his/her macular pigment opticaldensity (MPOD). The MPOD is a measurement of the attenuation of blue light by macularpigment and is linearly related to the amount of lutein and zeaxanthin in the macula. We
measured MPOD in 55 participants and compared it with their discomfort glare thresholddetermined psychophysically by exposing the participants to a series of varying light intensity.
2. Methods
A total of 55 young healthy individuals, without any visual impairments and between 18 and35 years of age, participated in the study. Experiments were conducted in a controlled test
room environment equipped with instruments to measure thermal and visual parameters of theroom.
First, we measured the MPOD for each participant using a macular pigment screen er device,
MPS II, that uses the heterochromatic flicker photometry method to provide an estimate of theblue light absorption of MP. In this test, participant viewed a centrally fixated target and madeflicker matches at two light wavelengths of 465nm (blue light) which is absorbed by the MP
and another of 530nm (green light) not absorbed by MP. Flicker matches were made in the
foveal region of the retina. The MPOD values are measured on a scale of 0 to 1, a lower value
indicates higher level of blue light hitting the macula.
After that, participants’ sensitivity to glare was evaluated experimentally where participants
were asked to rate glare from a dimmable electric light with predefined levels of varying
intensity that the participants were exposed to in their near foveal field of view. The LED glare
source was of diameter 10cm, CCT of 4800K with a diffuser sheet, and the angle between
glare source and participant’s line of sight was 20°. Note that the glare source was the only
light source in the test room. During the experiment, participants were exposed to 9 lightlevels that differed in glare stimuli luminance ranging from 265363 cd/m 2 (UGR = 36) to 2000
cd/m 2 (UGR = 8) designed to cover the glare sensation spectrum from imperceptible (UGR <10) to intolerable glare (UGR > 34). After being exposed to each light level for 20 seconds,
participants first rated the glare from the light source on a binary Yes/No scale and also on a
6-point Likert scale. The first 3 light levels, which varied from lowest, mid dle and highest lightintensity, were the training conditions and were thus not randomized between the participant
to avoid anchor bias. The next 6 light levels were the testing conditions considered in theanalysis and were thus randomized to avoid order bias. In the testing conditions, one light63

CIE 2021 - Abstract Booklet

intensity was repeated to check the consistency of the evaluation done by the participant. The
light intensity at which a participant’s discomfort glare rating changes from ‘No’ discomfort to‘Yes’ discomfort was taken as the glare threshold value for that participant. If the thresholdvalue of a participant is higher than mid-level intensity shown to all the participants, they areclassified as less sensitive and vice-versa for more sensitive group.
To further confirm the glare thresholds, a post-trial session was conducted where participants
were exposed to continuously increasing intensity of the LED until they reported visual
discomfort and the intensity value was recorded. Participants also self -reported their
sensitivity to bright light on a 0-10 numerical scale.
3. Results
Discomfort glare thresholds obtained are well distributed across the range of light intensity
shown to the participant varying from UGR = 8 to UGR = 36 indicating the inter -individual
variability. The MPOD levels among the sample range from 0.14 to 0.86 with an average of
0.48.
We compared the glare ratings of the repeated light level within -subject and found themconsistent in 86% of the participants. The glare thresholds obtained from the experiment werein agreement with those obtained from post-trial session (Pearson’s correlation coefficient
ρ=0.61).
Based on the glare thresholds, we found 47% of the participant less sensitive and 53% moresensitive to glare in our sample. We compared the mean differences in MP levels by applying
a Kruskal-Wallis test on the two groups which resulted in a p-value of 0.0466 (χ2 = 3.95)
indicating MP levels are significantly different between the groups at α=0.05.
4. Conclusions
This paper presents a study aimed at evaluating a person’s sensitivity to glare and comparing
it with the measured MP levels in the foveal region of retina. Method followed to quantify glaresensitivity threshold was found to be consistent in evaluating within -subject responses. MP
levels were found to be significantly different between the two groups less and more sensitive
to glare. However, MP levels were found to be lower in the group having higher glare
thresholds which contradicts the previous studies. Additional data is needed to validate thefinding and confirm the influence of the macular pigment density on subjective evaluation ofglare scenarios. There is also a need to further extend the study in daylit conditions that arecloser to real-life conditions64

CIE 2021 - Abstract Booklet

OP22
USER EVALUATIONS OF CONTRAST-DOMINANT DISCOMFORT GLARE IN DIMDAYLIT SCENARIOS: PRELIMINARY FINDINGS
1

Quek, G.1, Wienold, J.1, Andersen, M.1
École Polytechnique Fédérale de Lausanne, Lausanne, SWITZERLAND
geraldine.quek@epfl.ch

Abstract
1. Motivation, specific objective
Daylighting in buildings not only serve as an energy-saving, flicker-free source of illumination,
but also has many benefits towards human health and well-being. However, daylighting also
brings about problems such as visual discomfort and over-heating. One way to maintainoccupants’ visual comfort is to reduce discomfort glare. Discomfort glare metrics ty picallyconsider at least one of the two types of discomfort glare effects, saturation and contrast
effects, in their equation. The former occurs when there is an excessively bright glare sourcein the field of view, while the latter occurs when there is a high luminance ratio between theglare source and the adaptation level of the eye. Recent studies showed that while hybrid
metrics, like Daylight Glare Probability (DGP), outperform other single -effect metrics,
contrast-driven glare metrics were found to describe discomfort glare responses better thansaturation-driven ones in dim environments with lower adaptation levels. Although DGP works
relatively better in most scenarios, there is still room for improvement in glare prediction for
scenarios outside of the range of brightly lit scenarios from which it was developed. Annual
glare simulations in a typical open-plan office in Geneva also showed that contrast-dominant
glare scenarios occur far more frequently than saturation -dominant scenarios. To this end, we
designed and executed a user study to investigate the discomfort glare evaluations in dim
daylight office environments with low adaptation levels. We hypothesize that DGP
underpredicts discomfort glare evaluations in dim scenarios where the contrast e ffect isdominant, and that it may be necessary to reconsider a reformulation of DGP to account forthe discomfort glare prediction, for example through increasing the weight of the contrast termor proposing a new contrast term. In this paper, we report p reliminary findings from our user
evaluations of discomfort glare in dim office-like environments to confirm the above
hypothesis, in a quest to extend discomfort glare metrics to a wider range of scenarios.
2. Methods
We conducted a user study in a controlled laboratory setup mimicking an office-likeworkspace, creating a glare source from a diffuse window panel in dim adaptation levels,
using diffuse films and neutral density window films. A full -factorial experiment design with 2
independent variables, luminance and size of the glare source, at 2 levels each were explored,
leading to 4 experiment setups. Human participants 18 to 30 years old were recruited for theexperiment, the age limit was intended to reduce the effects of aging on glare evaluations. In
the experiment protocol, participants first answered a baseline questionnaire on basic
demographic information which was kept pseudonymized. Participants then worked on a re typing task for 10 minutes under each of the 4 lighting conditions (“1 -panel-high”, “1-panellow”, “2-panel-high” and “2-panel-low”), which were presented in a randomized order for allparticipants. They were then asked to complete a sampling questionnaire on the indoor
environmental quality after each scenario, including answering questions on discomfort glare
through the Osterhaus scale and also through a glare indication diagram. In this paper -based
diagram, participants were asked to colour where the glare source is located if theyexperienced any discomfort glare. High dynamic range (HDR) images and illuminance data
(horizontal and vertical) were captured continuously as key measurements for the
independent variables. HDR images were checked against vertical illuminance measurements
to ensure reliability. The luminance of the diffuse panel ranged from 4575 to 14953 cd/m2 witha mean of 9237 cd/m2, while the adaptation level (overall illuminance at the eye) was kept low;
the mean vertical illuminance ranging from 243 to 2153 lux with a mean of 815 lux. Horizontal
illuminance was kept above 300 lux to maintain the recommended desktop illuminance. Other

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confounding variables like thermal comfort and stable sky and weather conditions weremaintained for the experiments and were measured through indoor climate monitoringmeasurements, outdoor irradiation and others. The measured lighting data was then analysed
alongside the subjective responses in the sampling questionnaires to investigate theprediction ability of current discomfort glare metrics, such as DGP, in these scenarios. This
paper intends to show preliminary findings from approximately 30 user evaluations on the 4
low light scenarios.
3. Results
Based on the current recommended thresholds of DGP, all four lighting conditions would havebeen predicted to have “imperceptible glare” as the overall lighting conditions ranged from
0.19 to a maximum of 0.31. However, we found that while DGP predicted imperceptible glare
for all evaluated datapoints, participants still reported “noticeable” and “disturbing” glare in
two-thirds of the datapoints based on the Osterhaus scale from imperceptible to intolerable
glare. More than half of the scenes were indicated to be glary on the glare indication diagram.
Preliminary findings include that firstly DGP is likely underpredicting glare in these low-lightscenarios given the current formulation and thresholds. Initial correlations also show that thereason for glare in such scenarios is mainly due to contrast. Hence, results show that there isa tendency for DGP to under-predict discomfort glare in these scenarios and this signifies aneed to reformulate the equation to adapt to dimmer scenes with lower adaptation levels.
4. Conclusions
This study aimed to fill the gap by investigating dim daylit scenarios where there was a lack ofglare evaluation datapoints. These scenes in generally dim conditions commonly occurs indeep open-plan offices. To have a full control of lighting, task and environmental parameters,
we carried out user evaluations in an office-like laboratory setup. Preliminary results from theuser evaluations in low-light daylit scenarios mostly confirm previous findings where glare in
low adaptation levels is mainly contrast dominant, and thus contrast -driven glare metrics tend
to perform better in predicting glare in such scenarios . Hybrid metrics such as DGP seems to
not correlate with reported glare in such scenes. Future research should focus onreformulation of the metric to extend applicability to dimmer scenes and adaptability to awider range of scenarios.

66CIE 2021 - Abstract Booklet

OP23
A GENERIC GLARE SENSATION MODEL BASED ON THE HUMAN VISUAL SYSTEM
Vissenberg, M.C.J.M., Perz, M., Donners, M.A.H., Sekulovski, D.
Signify Research, Eindhoven, THE NETHERLANDS
Gilles.vissenberg@signify.com

Abstract
1. Motivation
Before the introduction of the unified glare rating (UGR, CIE117-1995), discomfort glare byelectric lighting was evaluated by many different national glare measures (see CIE 055 -1983).
All these measures contained similar features, but with different parameters, because they
were empirical models based on a fit to different experimental datasets. The consensus
reached on a single glare measure has allowed UGR to become a widely accepted quality
measure for indoor electric lighting, next to aspects like illumination uniformity, colour
rendition, and temporal artefacts like flicker. In other lighting application fields, a unified
approach to discomfort glare is lacking, as demonstrated by the large number of (sometimes
only slightly) different glare measures that have been proposed for daylight in bu ildings, roadlighting, car headlights, or sports lighting (known under the abbreviations DGI, PGSV, DGP,
GCM, CBE, GR, etcetera).
Despite its apparent success, UGR has several shortcomings, like the limited range ofallowed source sizes (no small or large sources), or the fact that spectral effects andoverhead glare are not accounted for (see e.g. CIE 232-2019). To account for all thesevariations in glare source properties and application conditions, a more fundamental approachis needed.
The single connecting element in all this is the human observer that experiences the glare.
Even though the light source may range from an LED to the sun, and application conditions
may vary from a pitch-dark road to a brightly lit office. In the end the glare is experie nced by ahuman observer who is confronted with a brightness that does not match his/her adaptation
state, either in space (a high contrast between source and background) or in time (switching
on a bright source, or entering a bright space). Whatever the n ature of the lit environment, it
will generate a sensation in the human visual system that may be quantified in terms of its
physiological characteristics.. It is expected that this is universal for all sources andapplication conditions. The actual glare perception is of course still influenced bypsychological and contextual factors and will require a fine -grained approach, tuned to thedetails of the situation.
Such a generic glare model, based on the physiology of the human visual system (HVS), is
the aim of the recently started CIE TC 3-57. The goal of this TC is to develop a new model toimprove understanding, calculation and criteria for the evaluation of discomfort glare. It willmodel the glare sensation from a physiological viewpoint to make it app licable for various
types of lit spaces and light sources (both indoor and outdoor) and to allow consideration ofoccupant profiles (age, visual ability, etc.) in lighting design.
In this paper, we provide an example of such a glare model, an outline its e lements that
describe the visual system, and a few applications to typical indoor and outdoor lighting
situations.
2. Methods
We have developed a model of the HVS that takes into account several aspects of the human
eye that are relevant for experiencing glare. The aim is to re-use as much as possible existingknowledge based on measured data in optometry, neurology, and perception science.
Wherever applicable, simplified mathematical descriptions known from computer visionmodels are applied. Main elements of the model include:67

CIE 2021 - Abstract Booklet

constriction of the pupil, depending on the eye illuminance, age, and iris colour

retinal image formation, influenced by eye lens, scattering in the eye, and eye movementscone response, depending on the adaptation state (light histo ry)cone signal filtering by retinal ganglion (and other) cells, modelled by a Difference ofGaussians filternonlinear addition of neural signals

3. Results
The model is tested on a typical indoor lighting situation with a uniform light source, and on a
typical outdoor lighting situation, with both uniform and non -uniform light sources. It is shown
that, using simulated environments with one luminaire varied in size and in luminous flux, themodel correlates well to UGR for the indoor situation. The model also correlates well to
subjective glare ratings that were reported in the literature for an experiment performed at
typical outdoor lighting conditions.
4. Conclusions
An example of a physiological glare sensation model is presented, which describes sever alelements of the HVS that may have an effect on the glare sensation (pupil constriction, lightscattering, cone adaptation, and neural filtering). These first tests are promising in the sensethat the model correlates well with glare responses for very d ifferent application settings andsource types. The presented work constitutes a step forward in developing a glare model
unified across applications. However more work is needed to fine -tune its elements, and many
more tests are required to demonstrate validity of the model to the wide spectrum of
applications and sources it aims to describe.

68CIE 2021 - Abstract Booklet

Session OS7
D3 – Daylight
Tuesday, September 28, 14:00–15:30

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OP24
THE ROLE OF DAYLIGHT IN LIBRARY USERS’ SEAT PREFERENCES
Izmir Tunahan, G., Altamirano-Medina, H., Unwin, J.
Institute for Environmental Design and Engineering, University College London,
London, UNITED KINGDOM
gizem.izmir.tunahan.17@ucl.ac.uk
h.altamirano-medina@ucl.ac.uk, jemima.unwin@ucl.ac.uk

Abstract
1. Motivation, specific objective
Academic libraries play a significant role in students’ learning process by providing anenvironment that enhances the students’ learning experience and c ontributes to theiracademic and intellectual development.
Seating that meets the needs and preferences of students can promote a longer stay in thelibraries and keep students motivated, which in turn influences their emotions and learning
abilities. However, studies regarding seat preference in learning environments have mostly
focused on the interior elements, such as colours and furniture. Existing knowledge on theinteraction between daylighting and seating preferences is limited. This study aims tounderstand how study spaces are used, what type of spaces are most in -demand, and therelationship between seat occupancy and daylight availability.
2. Methods
Occupancy data of the UCL Bartlett library was assessed concerning daylight availability.
Three main study areas were investigated: the group study area, the collection area and thequiet study room. The group study area accommodates shared desks and individual cubicles
and has windows oriented North; the library collection area has shared and individual desks
and windows facing north and east; the quiet study room is an open-plan space with a skylightand shared desks.
Horizontal illuminance at each desk of the UCL Bartlett library was compared with theoccupancy rate at 10-minute intervals between 2018 and 2019. Daylight availability was
obtained from daylight simulations and external illuminance data from Public Health England.
The occupancy ratio of the desks was acquired from motion sensors located underneath eachdesk. The interaction between daylight availability and the desk’s utilization was analyzed
considering the frequency of selection, order of preference, unoccupied periods and occupant
behaviours in the early hours and after sunset.
3. Results
The study revealed that daylight conditions significantly influenced seating preferences inplaces daylit by side windows rather than a skylight. Access to an outdoor view andacceptable daylight levels makes certain desks more preferable. Seats with a goodcombination of daylight and privacy are in more demand than the seats providing only
appropriate daylight levels. Students arriving earlier to the library tend to select the individual
desks with acceptable levels of daylight followed by less private desks but with good daylightavailability. Desks with inadequate daylight are usually the last choice of the students.
4. Conclusions
Although daylight has a vital role in seat selection, other factors, such as quietness, outdoor
view and privacy, also matter. Future research should be devoted to developing an analysis
method to investigate the relative importance of daylight in interaction with other factors inseating choice.

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OP25
EFFECTS OF THE TRIPLE SPLIT WINDOW SCREEN ON VISUAL PRIVACY AND VIEW
IN THE RESIDENTIAL LIVING SPACE
1

Oe, Y.1, Saito, K.2, Souma, T.2, Yoshizawa, N.1
Tokyo University of Science, Chiba, JAPAN, 2 YKK AP Inc., Tokyo, JAPANyukioe@rs.tus.ac.jp

Abstract
1. Motivation, specific objective
The main role of windows for the lighting environment in residential living spaces is to ensur e
the brightness of the space by introducing daylight. In addition to this, windows provide views
and the sense of openness, and they help to create a living environment that is healthy forboth body and mind. However, in actual houses, window treatments s uch as blinds andcurtains are often used to ensure privacy, and it is liable to block daylight and views.
Previous research showed that the privacy at windows was composed of two phases, that is“gaze awareness”, which is the perception of being watched r egardless of the presence orabsence of the actual gaze, and “discomfort awareness”, which is the perception of being
uncomfortable with the perceived gaze. In this paper, we will focus on the former “gazeawareness” and try to confirm whether the relationship between gaze awareness (privacy)
and view from the room differs depending on the window screen conditions. The triple split
window screens with upper, middle, and lower layers were used in the experiment, and theireffects on visual privacy and view were examined.
2. Methods
The experiment was conducted in the artificial sky laboratory. The model of an interior space(one-story) and an opposing building (both at 1/4 scale) were set up in it. The subjects
consisted of 15 students (13 males and 2 females). A total of 66 conditions were prepared by
combining three experimental variables: window treatment (none, translucent screen, andcompletely lightproof screen (black cloth)), the position of the window treatment (upper,
middle, and lower layer), and the evaluation target (a female or male doll). The living room
was assumed on the ground floor, and the window was a sweeping type. The lighting
conditions were constant at 100 lux for the indoor horizontal illuminance and 10000 lux for theoutdoor horizontal illuminance.
The subject adapted to the evaluation space for 10 minutes. After that, the experimental
condition was changed by the experimenter, and the subject repeated the observation (30seconds) and evaluation of the indoor and outdoor spaces. The sub ject observed the indoor
space and the evaluation target outside the window by looking through a peephole in the front
wall. This paper deals with the following evaluation items: 1) Visibility level of the evaluation
target outside when observing it from the indoors (hereafter referred to as “visibility frominside”). 2) Visibility level of the indoor figure from the outside estimated by the subject in theindoors (hereafter referred to as “estimated visibility from outside”). 3) How fine the view isfrom the indoors (hereafter referred to as “view”). In this paper, the term “visibility” covers
both subthreshold and suprathreshold perception.
3. Results
The evaluation results in the case that a female doll was in the outside are shown as follows.
The evaluation of “visibility from inside” had a high correlation with that of “estimated visibility
from outside” (r>0.97). It was also confirmed that there was a proportional relationshipbetween the two, regardless of the window treatments. Therefore, it was sugge sted thatquantitative prediction of “gaze awareness” would be possible if the evaluation of “visibility
from inside” could be clarified using physical quantities.

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The prediction equation was constructed with the translucent level of each layer as ordinal
explanatory variables and the privacy evaluation (“visibility from inside” and “estimatedvisibility from outside”) or view evaluation as an objective variable. The coefficient of the
middle layer was higher than that of the upper and lower layers in all e valuation items. As thetransmittance level in the middle layer decreases, privacy can be secured, but the view
evaluation also decreases. It was also suggested that, when the lower layer is moretransparent than the upper layer, the “estimated visibility from outside” is comparatively low
compared to the level of the "visibility from inside”. It indicated that it was somewhat more
effective to decrease the transmittance level of the lower layer than the upper layer in order tosecure both privacy and fine views.
4. Conclusions and future works
The effect of the window shielding conditions on the evaluations of “visibility from inside”,“estimated visibility from outside” and “view” were examined through the experiment using ascale model. As a result, it was confirmed that the proportional relationship between “visibility
from inside” and “estimated visibility from outside” was established regardless of the window
screen conditions. In addition, it was found that the transmittance level in the middle layer o f
the opening had a large effect on both the evaluations of privacy and views, and the opening
in the lower layer is more effective than the upper layer in order to secure not only privacy but
also fine views when the living room is on the ground floor. In the future, we would like todevelop the method to estimate the “gaze awareness”, that is the privacy level, by
quantitatively calculating the “visibility from inside” using edge detection techniques withluminance images.

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OP26
ADAPTATIONS TO SUBJECTIVE INSTRUMENTS FOR DYNAMIC VIEW ASSESSMENTEVALUATION
1Rodriguez, F.1, Garcia-Hansen, V.2
Queensland University of Technology, Brisbane, AUSTRALIA
rodrigf3@qut.edu.au

Abstract
1. Motivation, specific objective
Recent studies in environmental psychology have provided new directions to understandoccupants’ well-being in indoor settings. Scholars have posited that restorative responses
triggered by the environment are likely to vary over time, thus highlighting the need forevaluation procedures that help to capture the role of dynamic environmental attributes on
occupants’ well-being. One possible way to achieve this objective is to focus on theassessment of outdoor views.
Windows have long been established as an important part of the luminous environment, li kely
to increase restoration and job satisfaction and decrease stress levels. Not only aesthetic
features and daylighting are provided by views, but also dynamic luminous information thatbrings in clues about the weather, the season, and the time of the d ay. Recent studies haveaddressed the role of dynamic attributes in views in depth, using systematic classification andcollection techniques to capture lightness changes over time, and virtual reality interventions
to test subjective responses to daylight changes in mixed urban views. These studies haveshown that positive responses to views are strongly mediated by dynamic outdoor lighting
conditions, thus likely to influence well-being responses over time. Although these results arepromising to broaden the scope of occupant-centered solutions based on the dynamic
processes sustaining indoor well-being, further work is required to fully address subjective
responses to dynamic luminous attributes in views. For instance, current metrics to examine
the different constructs in view research are based on instruments that were designed toinvestigate individuals’ responses through static view stimuli (e.g., photographs), thus
disregarding the range of variations depicted in the dynamic assessment of views. As a result,current interpretations of views may endorse research outcomes that do not necessarily
correlate with the subjective impression of views over time, limiting our understanding of how
to design for continuous indoor well-being.
To adjust subjective view instruments so that they cover for changes in views over time, it isfirst necessary to map distinctive labels and prevalent constructs currently used for view
assessment. In this study, a systematic review of the literature regarding view labels, vie w
constructs, and view instruments is presented, and preliminary adjustments to these
instruments are introduced. The findings in this study will help to define more robust view
assessment procedures that consider the effects of time and environmental cond itions on theoverall responses to the indoor environment.
2. Methods
To ensure reliability, a systematic search of peer-reviewed articles was conducted in Scopus
considering a 20-year publication range. First, a literature search was conducted by definin g alist of relevant terms (e.g., View, Window, Landscape, Urban, View Quality, and Windowless)contained in the article title, abstract, or keywords. Next, citation searching among theretrieved studies was conducted, which added papers that used similar descriptors to thoseestablished in the first selection. A first filtering criterion was defined to confirm the internal
validity based on the abstract content. Next, a full-text sift was used to refine the sample andensure pertinence. A second filtering criterion was defined based on the type of study. Using
these filtering techniques, the evidence base was consolidated, including 59 original research
papers.

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3. Results
First, distinctive labels in view research were revised. From the evidence base, 43 s tudies
reported a wide range of labels to describe view types. All labels (n = 154) were tabulated andre-classified using a semantic approach. Three types of view labels emerged from thiscategorization: content-type, configuration-type, and environment-type. An estimated 70% of
all reported view labels corresponded to the content-type category (i.e., either Natural or Built
features), thus raising the issue of representativeness and whether the recurrent labels caneffectively characterize dynamic viewing conditions in urban environments.
Next, recurrent view constructs were examined. All the articles in the study reported theconstructs used for view assessment. Four categories encompassing the semantic diversity of
constructs in outdoor view research were found: preference, restoration, performance, andimageability. Of these, the restoration construct showed the highest sustained growth among
all categories, and the performance construct presented the highest research increment overthe past 5 years. These findings are consistent with the development of subjective
instruments for measuring indoor well-being, thus framing the instruments feasible to be
adjusted for capturing environmental changes over time.
Following the categorization of view labels and view constructs, subjective instruments
implemented in the field and experimental studies were examined. The set of questions posedby different instruments were classified using thematic analysis. Two underreported factors(i.e., the environment type label and the imageability construct) presented a strong potential
to capture dynamic aspects of views moving forward. Semantic adjustments to standardized
instruments were also proposed, yet additional work is needed to validate these inputs withhuman participants.
4. Conclusions
Scholars in behavioural research have highlighted the importance to develop tools that help to
capture the effects of dynamic environmental attributes on occupants’ well -being. In this study,
an overview of the literature in view interventions (i.e., experimental and field studies) ispresented, aimed at defining adjustments to standardize view instruments so that they capture
the range of variations depicted in window views. Distinctive labels and recurrent view
constructs were examined over the evidence base (n = 59). The findings in this study set thefoundations for new subjective instruments that capture the effects of dynamic attributes inviews on indoor occupants.

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Session OS8
D1/D2 – Temporal light modulation
Tuesday, September 28, 14:00–15:30

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OP27
CALIBRATION OF PHOTOMETERS FOR TEMPORAL LIGHT MODULATIONMEASUREMENTS
1

Dekker, P.R.1,van Bloois, A.L.1
VSL, Delft, THE NETHERLANDS
pdekker@vsl.nl

Abstract
1. Motivation, specific objective
LED-based light sources are often used in pulse width modulation mode to lower theiroperating temperature and to enable dimming. This is known to introduce temporal light
modulation (TLM), a fluctuation of the emitted light over time. The resulting visual effects, e.g.
flicker and stroboscopic effect, are known as temporal light artefacts (TLAs). Severity of thelatter two TLAs can be expressed in a metric for short-term flicker of the illuminance asmeasured with a light flicker meter (PstLM) and the stroboscopic visibility measure (SVM),
respectively. Light sources entering the European market are now subject to limits for flicker
and the stroboscopic effect, as laid down in the Ecodesign 2019/2020 ‘Single Lighting
Regulation’. However, the metrological infrastructure to provide validated SI -traceable
measurements of TLM is currently not available and internationally agreed standards do notexist. A crucial step towards SI-traceability for TLM measurements is the calibration andcharacterization of TLM measurement devices.
2. Methods
A first step to SI-traceability for TLM measurement devices is a calibrated reference TLM
source. This source is calibrated against a well-characterized and calibrated TLM reference
meter. The TLM reference source is realized by coupling temporally modulated light f rom a
HeNe laser into an integrating sphere. The laser light is modulated with an acousto -opticalmodulator (AOM) which is driven by an arbitrary waveform generator (AWG). The output of
the AOM is modulated with a sinusoidal waveform. To provide an offset illuminance, the lightof a second unmodulated laser is coupled into the integrating sphere. The additional laser
light effectively lowers the TLM of the source. By adjusting the modulation depth of themodulated laser or the power of the continuous laser the level of TLM can be adjusted.
The TLM reference meter comprises a silicon photodiode, an amplifier, a digitiser, andsoftware to calculate the TLM metrics. The voltage scale of the reference meter is traceable
to a Josephson voltage standard through a multifunction calibration facility. The time scale istraceable to a 10 MHz reference frequency. The reference meter, in parallel to a device under
test, measures the TLM of the source.
The TLM facility, comprising the above-mentioned reference meter and source, was initiallydesigned for calibration of photometers in percent flicker, flicker index, and flicker percent(LCD contrast RMS method). However, the facility has now been characterized to assess its
potential for calibrations in terms of the more recent metrics for flicker and stroboscopic effect.
This paper will describe the characterization and calibration of the TLM facility to this end.
3. Results
To generate a sinusoidally modulated optical stimulus at a single frequency, e.g. 50 Hz, linear
conversion of the AOM driving voltage to transmitted optical power is essential. The AOM
showed a nonlinear behaviour of transmitted optical power at the low and high end of its
range. This nonlinearity would introduce a deformation of the sinusoidal modulatio n of the
optical power. To avoid this, care was taken to operate the AOM within its linear range. The
linearity of the AOM has been measured. The optical power could be modulated linearly with
about a factor of 3. Because the second continuously operated l aser provides an offset
illuminance, relatively low levels of TLM could be achieved.

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To assess the frequency bandwidth of the TLM facility the amplitude of the modulated laser
beam was measured with the reference meter at frequencies from 50 Hz to 50 kHz. The
bandwidth of the TLM reference source in combination with the reference meter is shown tobe greater than 50 kHz. This well accommodates the upper frequency for PstLM of about 200
Hz and the upper frequency for SVM of 2 kHz. The existing data analysis software of the
facility has been updated for PstLM computation. The newly implemented PstLM calculation
has been validated against waveforms generated with publicly available algorithms.
Implementation of SVM is planned for a future revision.
4. Conclusions
A facility has been realized to calibrate photometers with respect to TLM quantities. Though
the facility was initially built for percent flicker, flicker index and flicker percent, the methods
used proved suitable for PstLM and SVM. It was shown that t he bandwidth of the current TLM
facility is sufficient to accommodate PstLM and SVM. Because PstLM requires the acquisitionof longer time series e.g. > 180 s and is generally measured for non-sinusoidal waveforms,
both the function generator and data acquisition system will be updated in the future. The
latest results and the design of the TLM facility will be presented at the CIE 2021 Midterm
conference.

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OP28
SENSITIVITY ANALYSIS ON THE EFFECT OF MEASUREMENT NOISE AND SAMPLINGFREQUNCY ON THE CALCULATION OF THE TEMPORAL LIGHT AREFACTS
Thorseth, A.1, Lindén, J.2, Bouroussis, C.A.3
Technical University of Denmark, Roskilde, DENMARK, 2 Division of Ergonomics andAerosoltechnology, Design Sciences, Lund University, Lund, SWEDEN 3 Lighting Laboratory,
National Technical University of Athens, GREECE
andt@fotonik.dtu.dk
1

Abstract
1. Motivation, specific objective
Temporal light modulation (TLM) and the resulting temporal light artefacts (TLA) can cause
health and wellbeing problems for users of lighting products. Therefore, TLM has to bemeasured accurately and repeatable. This study will investigate important factors influencing
the measurement uncertainty of TLM measurements.
TLM is generally caused by LED sources fed by modulated power supplies which introduce
modulation of the light output. This leads to specific visual artefacts when seen by a humanobserver. TLM are typically more severe in low quality and, in most cases, low priced LED
lighting products. It would be unfortunate if the benefits from the incre ase in energy efficiency
from adoption of LED lighting technology would be offset by the negative consequences ofTLA. This issue has been of high research interest in recent years and resulted to specific act
against it.
The EU market regulation 2019/2020, which will replace Regulations No 244/2009, No
245/2009 and No 1194/2012 and will be in force starting on September 2021, includes
restrictions against TLA in lighting products. More specifically, EU regulation recognizes the‘stroboscopic effect’ as a change in motion perception induced by a light stimulus, theluminance or spectral distribution of which fluctuates with time, for a static observer in a non static environment. The metric for the stroboscopic effect used in this regulation is the ‘SVM’(stroboscopic visibility measure). The same regulation recognizes ‘flicker’ as the perception ofvisual unsteadiness induced by a light stimulus, the luminance or spectral distribution ofwhich fluctuates with time, for a static observer in a static environm ent. The metric for flicker
used in this regulation is the parameter ‘PstLM’. According to this EU regulation, flicker for
LED and OLED products should be less or equal than 1,0 at full -load while the stroboscopic
effect for the same products should be less or equal to 0,9 at full-load. Regarding theverification tolerances during market surveillance campaigns, values of PstLM andstroboscopic effect shall not exceed the declared value by more than 10 %.
Both TLA metrics are well defined and discussed in the CIE TN 006:2016 “Visual Aspects ofTime-Modulated Lighting Systems – Definitions and Measurement Models” which was a
product of a dedicated technical committee TC 1-83 Visual Aspects of Time-Modulated
Lighting Systems. Another CIE committee dedicated to this subject (TC 2-89) is actively
working on the preparation of a Technical Report and an International Standard on the“Measurement of Temporal Light Modulation of Light Sources and Lighting Systems” having
already published a Technical Note (CIE TN 012:2021). An EU funded research project(EMPIR MetTLM 20NRM01) on the metrology of temporal lighting modulation is scheduled to
run from 2021 up to 2024, dealing with specific metrological aspects of this complicated issue.
In practice, the measurement of TLM and TLA is expected to take place in both laboratory
conditions and in the field. Current measurement methods incorporate a variety of instruments,
e.g., handheld, benchtop, camera based, etc. Each instrument may use different sampling
frequencies (fixed or signal dependent). In addition, field measurements may be affected byother light sources that are not properly isolated. Since the measures of TLM and TLA aretime domain and frequency domain related, a dedicated signal processing algorithm should beapplied for each one. It is therefore clear that the final reported value of PstLM and SVM

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should be accompanied with uncertainties sourced from measurements as well as frommathematical calculations of the measured signals.
This study deals with the investigation of the calculation uncertainty of the TLA metrics, whenaffected by random measurement noise as well as the sampling frequency during
measurements. The preliminary results show that there are certain aspects in the calculationof the TLA metrics that can be significantly affected by the method of measurements and thealgorithm of arithmetic calculations.
2. Methods
This study includes an investigation of the calculation of PstLM and SVM on a variety of light
waveforms. Specifically, the methods consist of:

A set of mathematically calculated reference waveforms of various shapes andfrequencies

A set of measured waveforms from existing lighting productsApplication of random noise of various levels (e.g. 0-5%) to all the above waveforms



Calculation of PstLM and SVM metrics using specific signal processing algorithms forclear and noisy waveforms



Investigation of the relation between noise and variation on the calculation results

Investigation of the relation between sampling frequency and variation on thecalculation results

The above steps result in a sensitivity analysis on the calculation of the TLA metrics.
3. Results
The preliminary data of the study shows that the calculated value of PstLM can become
overestimated as a consequence of interference between sampling frequency and highfrequency components in the measured waveform. This can be the case even though thesampling frequency is well above the recommended minimum level of 2 kHz. It has also been
observed that the calculated value of SVM shows instability or high sensitivity to smallchanges in TLM frequency. PstLM was also found to be very sensitive to random noise.
Adding random noise on a measured waveform was seen to affect heavily PstLM, propagating
tenfold larger relative errors, from 0.1 % noise on the signal, resulting in a 1 % variation in
PstLM.
Since this study is ongoing, more results are expected to be presented during the conference
and more concrete conclusion will be drawn.
4. Conclusions
Measurement and calculation of TLM and TLA are sensitive to measurement uncertainties
that should be investigated and documented. This study contributes to the understanding of
the effect of random noise and sampling frequency on the finally reported values of PstLM
and SVM, which can be in some cases noticeable. These issues are likely to be of highimportance in relation to the upcoming regulations stated in updated EU eco design directives,
entering into force in September 2021.

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OP29
DEFINITION MODIFICATIONS FOR TEMPORAL LIGHT MODULATION (“FLICKER”)
Miller, N.J.1, Veitch, J.A.2
Pacific Northwest National Laboratory, Portland, OR, USA
2
National Research Council of Canada – Construction Research Centre, Ottawa, CANADA
Naomi.Miller@pnnl.gov
1

Abstract
1. Motivation, specific objective
The lighting industry, vision scientists, human factors researchers, and users have struggledwith the terms to describe the stimulus and the response to light that fluctuates in thetemporal domain. Often the word “flicker” is used to mean either the modulatin g light output(stimulus) or the perceptual response to the modulating light output. The official definition offlicker in the International Lighting Vocabulary (ILV) refers to the perception, not the stimulus.
There is no formal term in the ILV that describes the stimulus.
A recent literature review into this phenomenon identified and interpreted the terminologies
used, revealing inconsistency and a lack of specificity going back many decades. No grouphas been consistent in their use of terminology, and often researchers and practitioners
default to terms such as “flicker waveform,” “light flicker,” “flicker detection,” “flicker
perception,” etc. This imprecision hampers communication and impedes our understanding of
the topic. This paper discusses the terms in use today, and proposes clarifications based onrecent research results that could be incorporated in a future revision of the ILV. It isimperative for researchers, manufacturers, lighting professionals and medical practitioners to
use a common language to tackle the problem of unwanted responses to light that fluctuateswith time.
2. Proposals
To clarify concepts related to this phenomenon, its various manifestations, and its human
responses, the following terms are among those discussed. Some of t he terms appear inexisting CIE publications with definitions; this paper proposes modifications to them.
Temporal Light Modulation (TLM) – Fluctuation in luminous quantity or spectral distribution oflight with respect to time [CIE TN 012:2021]. Or, more descriptively, a light stimulus with awaveform that exhibits time-based modulation. The waveform may be completely benign or
potentially problematic. Some of these waveforms are potentially unwanted or undesirable tosome populations in specific applications and contexts. Human responses to TLM exposure
span a broad range of visual, cognitive, behavioural, neurological and physiological outcomes.
Term to be deprecated: Temporal Light Artefact (TLA) – Change in visual perception, induced
by a light stimulus, the luminance or spectral distribution of which fluctuates with time, for ahuman observer in a specified environment [modification from CIE TN 006:2016]. “TLA” isintended to mean a grouping of unwanted visual artefacts which vary with TLM frequency a ndviewing conditions: direct flicker; the stroboscopic effect, and the phantom array effect. It
should more clearly expressed as, “Artefacts from TLM,” or “Visual Perceptions from TLM.”
There are two concerns about this, 1. that the term “artefacts” in No rth America is frequently
used to mean trivial side-effects of an event or phenomenon, and 2. that a term for such agrouping is unnecessary since “visual perceptions from TLM” works equally well.
Direct Flicker – Perception of visual unsteadiness induced by a light stimulus, the luminanceor spectral distribution of which fluctuates with time, for a static observer in a static
environment [CIE TN 006:2016]. The modifier “direct” has been added here to differentiate
directly visible light fluctuations (on or off-axis view) from the generic term, and to differentiate
it from the stroboscopic effect which is detected indirectly. The frequency range for direct80CIE 2021 - Abstract Booklet

flicker is approximately 3 Hz up to 65, 70, 80, or 90 Hz, depending on the referenced article.
Whether or not the existing term should be retained in the ILV is a matter for discussion.
Stroboscopic Effect – Change in motion perception induced by a light stimulus the luminanceor spectral distribution of which fluctuates with time, for a static observer v iewing a moving
object [CIE TN 006:2016]. This is a response to a stimulus, but it requires a moving object in
the field of view for detection. The frequency range is roughly from 80 to 2000 Hz. We
propose the addition of this range to the definition.
Phantom array effect, also known as ghosting – Change in perceived shape or spatial
positions of objects, induced by a light stimulus the luminance or spectral distribution of which
fluctuates with time, for a non-static observer using large saccades in a static or non-static
environment [modification from CIE TN 006:2016]. These effects are spatially separated,
repeated retinal images due to the interaction of large eye saccades with a fluctuating lightsource or an object illuminated by that light source, wit h a frequency range of approximately
80 Hz to 11,000 Hz. We propose this frequency range be added to the definition, for added
clarity.
Static environment [modification from CIE TN 006:2016] – An environment that does notcontain objects that are moving .
Non-static environment [new] – An environment that contains object movement or relative
movement between observer and the observed environment.
Static observer [modification from CIE TN 006:2016] – An observer who does not movehis/her eye(s). An observer experiencing involuntary micro-saccades is considered static.
Non-static observer [new] – An observer who moves his/her eye(s), especially in large
saccades (>40°).
3. Conclusions
Although most groups, including the public, will continue to use the generic term “flicker,” itwill advance research going forward if the CIE can formally adopt clear vocabulary thatdifferentiates among stimulus and response; visual and cognitive, behavioural, andphysiological responses; and the three forms of visual response t o TLM. This paper issubmitted with the intent of opening up a discussion in the broader community.

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Session OS9
D4 – Benefits and disadvantages ofroad lighting
Tuesday, September 28, 21:15–22:45

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OP30
A NOVEL METHOD FOR STUDYING THRESHOLD LEVELS FOR POSITIVEPHOTOTAXIS IN INSECTS
Nilsson Tengelin, M.1, Jägerbrand, A.K.2, Andersson, P.3 Källberg, S1
Department of Measurement Science and Technology, RISE Research Institutes of Sweden,Borås, SWEDEN, 2 Department of Environmental and Biosciences, Rydber g Laboratory ofApplied Science (RLAS), School of Business, Engineering and Science, Halmstad University,
Halmstad, SWEDEN, 3 Calluna AB, Stockholm, SWEDEN
Maria.Nilssontengelin@ri.se

1

Abstract
1. Motivation, specific objective
Ecological impacts of artificial lighting and light pollution from roads may result in reduced
survival capabilities of certain natural species. Species that exhibits positive phototaxis, i.e.,they move towards light, are believed to be especially negatively influenced by artificial lightat night. Known examples include birds that are attracted to lighthouses or lit buildings,
insects that are drawn to road lighting and frogs that move towards outdoor light sources.
It has been suggested that the significant reduction of insects ove r large geographical areasin the recent decades could be caused by the presence of artificial light. Due to the positive
phototaxis, the insects fly towards the light source until they die of fatigue, get scorched oreaten by predators. This is a serious negative impact of artificial light at night since insects
have important functions in the ecosystems as pollinators, herbivores, decomposers and prey.
Previous studies have examined the effects of various spectral power distributions (SPDs) to
reduce the attractiveness for insects. Because the vision of insects partly overlaps withhuman vision, it is difficult to adapt the lighting in such a way that it has no impact on theinsects and yet satisfies the requirements for good visibility and acceptance for humans.
However, there are no previous studies that have investigated the influence of very low lightlevels for insects using LED lighting under controlled experimental conditions. Thus, there is alack of knowledge at which levels of light the insects ar e no longer influenced by artificial light,
i.e., the threshold level.
The purpose of this study was to design a new method for the study of threshold levels for
positive phototaxis in insects. Such method enables identifying at which light levels positive
phototaxis to artificial light in insects ceases.
The basic idea was to expose the insects to controlled levels of light and to monitor their
response in absence of any other influencing factors. In order to achieve this, it wasnecessary to create an artificial environment that allows for the low light levels needed todetect threshold levels for insects.
This paper will present and describe a novel method for studying threshold levels for positive
phototaxis of insects and smaller mobile organisms.
2. Methods
For the experiments, a rectangular light tight box was constructed with a light source at one of
the short sides. The insects are inserted in the box, one at a time at the opposite end from thelight source. The size of the box is 60x45x90 cm (WxHxL) and it is constructed of a material
that is very dark grey in the visible range but has a relative high reflectance (>60%) in thenear infrared (NIR) range. Two monochrome cameras with wide angle objectives monitor the
movement of the insects inside the box. For clear visibility, infrared LEDs (940 nm) were
installed in the ceiling of the box. This will not disturb the insects, as the radiation from theLEDs is outside of the visible range of most insects. Since the walls of the box have a diffuse
and low reflectance (5%) in the visible range and a high reflectance at 940 nm, there will be

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no noticeable reflections of the light source on the walls, yet the interior will look bright on therecordings. Thus, high quality film sequences of the movement of the studied organism canbe collected. A grid was drawn on the floor and back wall of the box to be able to determine
the position of the studied organisms.
The light source used is a conventional sphere-based luminance source with a glass cover
over the sphere opening to keep any insects out of the sphere. A mechanical shutter is used
to open or close the sphere so no stabilization time is necessary to reach stable light levels.
Also, the luminance source has an adjustable slit which enables varying the ligh t level in acontrolled manner without dimming the LED, thus maintaining the same SPD throughout theexperiment. The source can be equipped with different LEDs and in addition be used with
optical filters for tailored SPDs.
The type of insects used to test the new method is greater wax moth (Galleria mellonella), a
pest in beehives that is found in most parts of the world. G. mellonella is known to be
attracted to light in its adult stage of the life cycle. The species is commercially available, andthe moths are bred from purchased larvae and stored in special containers in the lab. Prior to
the test the moths are kept in a cool environment. The low ambient temperature decreases
the insect activity which makes them easy to handle. The experiments are perfor med at room
temperature (23°C) after an acclimatization period to the ambient conditions in the test box.
Feather-weight forceps are used for careful handling of the insects.
3. Results
Preliminary tests show that insects are clearly visible and can be suc cessfully monitored
inside the test box. High quality film sequences were obtained giving detailed information
about movement and behaviour of insect individuals. The light levels can be varied in a large
range and by using time and distance measurement in combination with captured film
sequences, the impact of the light on the phototaxis of insects and other organisms can bequantified. No observations indicated that the insects were reacting to the radiation from the
IR LEDs. The box is portable and could be constructed at a relatively low material cost.
4. Conclusions
The test box constructed gives capability to study the impact of different light levels on
various small species in a controlled and repeatable setting. It enables conducting
experiments with a control-impact experimental design and can be applied on insects andother small organisms, e.g., frogs, salamanders and small rodents. The design can
successfully be used to measure very low threshold levels of light of various spectral
compositions which makes it highly flexible. This novel and innovative method provides
increased possibilities of detailed studies of ecological impact of artificial light.

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OP31
INVESTIGATING LIGHT AND CRIME USING AMBIENT LIGHT LEVEL
1

Fotios, S.1, Robbins, C.J.1, Farrall, S.2
University of Sheffield, Sheffield, UNITED KINGDOM, 2 University of Derby, Derby, UNITED
KINGDOM
steve.fotios@sheffield.ac.uk

Abstract
1. Motivation
A local authority might ‘improve’ road lighting in an attempt to tackle street crime. Improvemight imply changes such as a higher light level, or installation in a previously unlit area. Anychange to road lighting brings the risk of complaint (warranted or not) from local residents, so
the local authority will want to be certain that the improvements are seen to be beneficial.
The efficacy of road lighting as a countermeasure to street crime is controversial – somestudies find an effect while others do not.
The 2008 Campbell Review by Welsh and Farrington included 13 studies from the UK and theUS, with which they compared crime numbers, before and after installation of improved
lighting, in test and control areas. Their analysis used a Relative Effect Size, an odds ratio,
and the result (overall RES=1.27, 95%CI-1.09-1.47, p=.0008) suggested a reduction in crime
following improved lighting. While statistically significant, this is a small effect, only justsurpassing the threshold for an effect of small practical relevance. It was also an internallyinconsistent result – in three studies crime increased after improved street lighting.
The intervention, improved lighting, is usually installed in areas with an existing problem ofhigh-crime rather than this being randomly assigned. Hence at the start of a trial the caselocation will tend to be worse (i.e. have a higher crime count) than control areas. Any
apparent benefit of lighting demonstrated in such studies may therefore be a result ofregression towards the mean rather than being an effect of the lighting. If regression toward
the mean persists, an area with high level of crime will tend towards a lower level of crime
regardless of the intervention, and will tend to decrease more than control areas which did notinitially display a high level of crime.
A later study by Chalfin et al overcame this by choosing test and control sites, at random,from 80 areas of high crime, hence both having the same potential for regression to the mean.
They found that temporary lighting reduced outdoor night-time crimes by 36%. However, themere presence of the temporary lighting may have influenced public behaviour rather thancrime reduction arising from the visual benefits of lighting.
Here we consider an alternative approach to investigating the relationship between light andcrime: the effect on outdoor crimes of changes in ambient light level, a method previously
used to investigate road traffic collisions.
2. Methods
Crime counts were compared for the days just before and just after clock change: the precise
daily time window was chosen so that it was dark befor e, and daylight after the clock change(or vice versa). The day/dark ratio of crime counts in this period were compared to those incontrol periods which were permanently daylit, or permanently dark, before and after the clockchange, thus isolating the effect if any of change in ambient light from other causes. In thisapproach there is no apparent intervention to influence outcomes, and each area acts as its
own control.
Data for this analysis requires record of the time and location of each crime in orde r toestablish solar altitude at the time of the crime hence to characterize daylight or dark: crimes

85CIE 2021 - Abstract Booklet

within civil twilight (a solar altitude between 0° and -6°) were omitted. This investigation useddata for over 35,000 crimes from three cities in the US, Austin, Chicago and Louisville, for theten-year period 2010 to 2019, obtained from the Crime Open Database.
3. Results
The overall odds ratio of 1.05 (95%CI=1.01-1.10, p=0.03) suggests a significant increase incrime after dark, although this does not reach the threshold for a small size effect (OR=1.22).
The analysis was repeated for each of the 32 categories against which types of crime wererecorded, including assault, burglary and disorderly conduct. This suggested a significant
increase in robbery after dark (OR=1.58, 95%CI=1.23-2.04, p<0.001) but not for any othertype of crime.
4. Conclusions
These data do not suggest that change in ambient light level, i.e. between daylight anddarkness, has a practically relevant effect on overall crime counts: in other words, thepotential benefit of lighting for crime reduction is limited.
The one exception to this is robbery, the (attempted) theft of property directly from anotherperson. Robbery requires the criminal to get close to the victim before initiatin g the act.
Pedestrians tend to look at other people, likely to assess their intent and identity, and theseevaluations are enhanced by better lighting. Being close to someone in better lighting
increases the risk of identification, and this might compromis e a criminal’s cost-benefit
consideration.

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OP32
OPTIMIZING ROAD LIGHTING TO REDUCE ROAD TRAFFIC CRASHES
Robbins, C.J., Fotios, S., Uttley, J., Rowe, R.
University of Sheffield, Sheffield, UNITED KINGDOM
steve.fotios@sheffield.ac.uk

Abstract
1. Motivation, specific objective
If road lighting is to be sustainable the installed characteristics should be sufficient to meetthe needs of the users, but no more. Unfortunately, the basis of road lighting standards tends
to be unreported which means we do not know if the recommended design characteristics are
in any way optimal. One approach to establishing optimal road lighting is to consider howchanges in lighting affect key outcomes such as the risk of road traffic collisions (RTCs). We
expect road lighting to influence RTC risk because it counters the reduction in hazard
detection ability that otherwise occurs after dark. We have studied the influence of ambient
light level on RTCs involving pedestrians and motorcyclists, two types of vulnerable road user.
This research contributes to the objectives of CIE TC 4-51.
2. MethodA first question is whether darkness has a significant effect on RTCs. This was investigatedusing an Odds Ratio (OR) to compare RTC frequencies in the weeks before and after the
biannual daylight savings clock changes. RTC cases are selected within strict time windows toensure a transition between daylight and darkness (before and after clock change, or viceversa) for the same time of day, thus to target the same road users. This day/dark ratio for thecase period is compared with a similar ratio for control periods to establish an Odds Ratio.
The control periods are those which are permanent daylight (or permanent darkness) acrossthe daylight and dark periods of the case period, and this account for the effects, if any, of
seasonal variations such as changes in weather. RTC data were drawn from STATS19, theUK database of police-reported RTCs, for the period 2005 to 2015.
3. Results
For both pedestrian and motorcycle RTCs, across the range of contextual situations, an OR
significantly greater than 1.0 was found: this confirms the expectation that darkness increases
the risk of an RTC. The data were further analysed to establish the specific situations in whichdarkness poses a significant RTC risk. For RTCs involving pedestrians, darkness is ofparticular detriment in adverse weather (OR=2.28, p<0.01), on rural roads (OR=2.62, p<0.01),
on high-speed roads (60 mph+, OR=4.69, p<0.01) and when using a pedestrian crossing(OR=1.47, p<0.01). For RTCs involving motorcyclists, darkness is of particular detriment at T junctions (OR=2.07, p<0.01), controlled by a ‘give way’ sign (OR=1.75, p<0.01), and on roads
with a speed limit of 30 mph or less (OR=1.73, p<0.01).
4. Conclusions
One way to optimize the use of road lighting is to light only those sections of road where lightlevel, and hence visibility, is an important factor. For motorcyclists, the data first suggest give way T-junctions are such a location, and hence lead a suggestion for lighting ju nctions but notconnecting sections of road. However, the data were further analysed to compare lit and unlit
roads, and this did not suggest a benefit of road lighting at junctions (OR=0.96. p=0.91). A
common cause of motorcycle RTCs is that the driver looked-but-failed-to-see: these datasuggest an alternative means of raising motorcycle conspicuity is required.
Darkness appears to be of particular detriment to pedestrians on pedestrian crossings and onhigh speed, rural roads. These are cases where pedestrians are generally unexpected. For
pedestrian crossings it is the presence of the crossing itself that is unexpected: once thedriver is aware that they are approaching a crossing then their expectation of encountering a

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pedestrian is raised, and lighting should then target enhancing the visibility of any pedestrians
on the crossing. The data suggest a benefit to alternative means for raising the conspicuity ofa pedestrian crossing. Pedestrians on high speed roads tend to be those involved with avehicle breakdown: these occur in unpredictable locations so a fixed lighting response is notsuitable, an alternative means for raising pedestrian conspicuity is required.
This presentation will suggest those situations where road lighting is suggested to be ofsignificant benefit in countering RTCs.

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Session OS10
D3 – Residential lighting
Tuesday, September 28, 21:15–22:45

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OP33
LIGHTING CONDITIONS IN BRAZILIAN AND COLOMBIAN HOME OFFICES: A
PRELIMINARY STUDY BASED ON OCCUPANT´S PERCEPTION
1Amorim, Cláudia Naves David1, Vásquez, Natalia2, Kanno, Julia Resende3
University of Brasilia, Brasília, BRAZIL, 2 Federal University of Santa Catarina, Florianópolis,
BRAZIL, 3 University of Brasilia, Brasília, BRAZIL
Clamorim@unb.br

Abstract
1. Motivation, specific objective
In the last year, people around the globe have been recommended -or have been forced- tostay at home, as a measure to mitigate the spread of the COVID -19 virus. Consequently,
dwellings have become the most used indoor environment where all, from c hildren to adults,
performed daily activities usually carried out in facilities specifically designed for it. As a
response to the pandemic measures, most people have been adopting the home -officescheme, transferring the workplace to home. Under this scen ario, occupants must adapt the
spatial configurations in their homes, as the lighting conditions required to perform a wide
range of visual tasks. The multiple benefits of adequate lighting and daylighting exposure
have been highlighted in the last years, while the current health crises have leveraged suchmatters over the past months. The future design of dwellings might contemplate similar
scenarios, leading to re-think how the housing has been traditionally conceived towards a
broader understanding of the future possible needs of their occupants. In this context,
exploring the lighting conditions in home offices, from the occupant’s perspective, is importantfor understanding the quality of the visual environment at home. This preliminary study, basedon data collected in Brazil and Colombia, aimed to investigate whether regional and personal
characteristics affect the visual perception and satisfaction of professionals regarding theluminous environment in those spaces adapted into home-offices. This study is part ofbroader research related to Subtask A of IEA Task 61 “Integrated Solutions for Daylighting
and Electric Lighting”.
2. Methods
Occupant’s subjective assessments were collected from December 2020 to March 2021
through an online survey distributed across Brazil –Latitudes between 5.75°N and 33.76°Sand Colombia – Latitudes between 12.44°N and 4.21°S- in the mother tongue of each country-i.e. Portuguese and Spanish, respectively-. Google Forms was used for the implementationof the survey, while its dissemination, among professionals from each country, used diverse
social media platforms –Mailing lists, Linkedin, ResearchGate, Facebook and Instagram -. An
introductory section of the survey presented information about the study aim and the survey’s
content to the participants. Each participant was required to provide informed consent before
taking part in the survey. The questionnaire, composed of 6 main sections, contained 37
questions. In this preliminary study, we are presenting the results collec ted through 4 of these
6 sections: i) “General Information”, where personal information was collected -gender, sex,
age group, city of residence, employment nature-; ii) “Lighting Condition in the whole Home
Office room now” and iii) “Lighting condition in the home office area now”, where theparticipants evaluated the satisfaction and perceptions regarding the current lighting
conditions – 7 point Likert scale-; and finally iv) “Description of Home Office”, where theparticipants were asked about the home-office activities and duration as well as the featuresof the room -as lighting fixtures and window shading devices-. The analysis addressed thedifferences in occupant’s perceptions and satisfaction due to personal characteristics –as
gender and age group-, country and latitude. The latitudes were grouped into three ranges forthe analyses: from 7°N to 9.9°S (LR1), corresponding to Colombia, from 10°S to 19.9°S (LR2)and from 20°S to 34°S (LR3), both corresponding to Brazil.

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3. Results
A total of 159 professionals took part of the survey. In Colombia (n= 63), both gender had thesame participation (49.2% women and 50.8% men) while in Brazil (n = 96), women had
slightly higher participation (63.6%) than men did. In both countries, most of the participants
were between 30 and 40 years of age (32.3% in Brazil and 39.7% in Colombia). In Brazil,
participants were from 31 cities, most of them located in latitudes between 11.7°S to 31.7°S.
Colombian participants were from 10 cities, located between 1.2°N to 6.33°N of latitude. A
large number of participants (41.7% in Brazil and 46% in Colombia) must use the bedroom,
dining- or living-room to work. However, Brazilians were more likely to have a separate room
dedicated to the home-office (54.2%). Four questions related to the satisfaction with the
daylighting and artificial lighting during the survey time were used to calculate a score ofgeneral satisfaction with the visual environment. Ranging from 0% to 100%, higher scoresindicate higher satisfaction. The scores showed less satisfaction of those Brazilians locatedbetween 20°S and 34°S latitude (LR3) than participants in the other two latitude ranges. By
gender, slight differences in the general satisfaction score were identified in Colombian(Mdn Females = 79%, Mdn Males = 82%) while, Brazilian woman (Mdn= 75%) were less satisfied
with the general lighting conditions than men (Mdn= 86%). Additionally, Brazilians from 20 to
30 years of age and Colombians from 30 to 40 years of age seemed to be less satisfied withthe general lighting conditions than participants in other age group were (Mdn= 75% and
Mdn= 71%, respectively). Regarding the perception, most of the participants perceived thecolour of the surfaces without distortion (53.9% Colombia and 59.4% Brazil). This co uld be
explained by the hour of the survey which was answered for most of participants during
daytime (only 10 people answered at night). It was found a correlation between the score ofgeneral satisfaction and the perceived level of light. In both countri es, participants thatperceived the home office area as “bright” had higher general satisfaction. The distribution of
the light was related to the general satisfaction of Colombian participants only, whose seem toprefer uniform lighting conditions in the home office area. For Brazilians, higher satisfaction
scores were associated to invisible glare and soft shadows in the home -office area.
4. Conclusions
This preliminary study aimed to explore lighting conditions in home offices, a new tendence
that is a consequence from Coronavirus pandemic. Probably most residential buildings are
not prepared to receive this kind of visual tasks and it is important to collect data tounderstand characteristics and need for home office lighting. The study identified severa lfactors related with home office lighting, some of them correlated with latitudes: in generalmore satisfaction was found from low to middle latitude ranges. In lower latitudes (Colombia)
the uniformity of lighting is the most effective cue related with satisfaction, in the other ranges(Brazil) satisfaction is related with glare absence and soft shadows. The first approach is partof a more comprehensive research that includes a master dissertation aiming to understandthe quality of the visual environment at home. These outcomes will be further explored andcan be used in generating new data about lighting in home offices, in order to subside
guidelines to improvement.

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OP34
ANALYSES ON OCCUPANT PATTERNS AND ENERGY CONSUMPTION IN
RESIDENTIAL BUILDINGS INCLUDING THE COVID-19 PANDEMIC
1Manav, B.1, Kaymaz, E.2
Faculty of Art and Design, Department of Interior Architecture and Environmental Design,
Kadir Has University, İstanbul, TURKEY,2
Bursa Faculty of Architecture, Department of Architecture, Uludağ University Görükle
Campus, 16059, Bursa, TURKEY
banu.manav@khas.edu.tr, ekaymaz@uludag.edu.tr

Objective
Recently, a comprehensive view of health has started to be included in building design
guidelines. Moreover, as a result of environmental concerns, demographic shifts, changes inlifestyle during COVID-19 crisis, the role of healthy buildings in addition to the main lighting
design principles are highlighted. Therefore, today’s lighting design issues include social well being, mental well-being, and physical well-being more than we discussed in the last century.
Hence, we are familiar with occupant centric and performance based metrics for building
types. According to data from the Republic of Turkey Energy Market Regulatory Authority, t heelectricity demand of Bursa has reduced 2.66% by the impact of lockdown in January 2021;
yet, electricity used by households increased 11.07% when compared to January 2020. This
increased consumption of energy is mainly driven by HVAC, lighting and home appliances use
because of higher occupancy patterns during daytime hours. In the present study, the specificobjective is to analyse the extended home living patterns and lighting energy consumption inresidential buildings, which became our living and working environment since the beginning of
the COVID-19 pandemic. The structure of the paper will include;

analyses of pre-design as well as evaluation of occupancy patterns,

improvement of interior lighting design regarding occupancy patterns,consideration of lighting conditions by static and annual climate-based dynamic
methods,

comparison of electric energy consumption concerning daylight factor with electricallighting control systems



integration of different simulation programs to fill the gap betwee n indoor lighting
system design and lighting energy consumption

MethodA survey is designed to evaluate occupant patterns for the selected residential units withdifferent facade orientations, obstruction angles, lighting and room properties. Before COVID19, a questionnaire was prepared and a pilot study was conducted face to face with residents
by taking all related permissions from the site administration. There were questions on lighting
preferences, visual comfort perception and energy saving awarene ss of the occupants.
Among the questionnaires, which were distributed to 84 residential units, 56 were filled incompletely and returned back. The SPSS 22.00 statistical program was run to evaluate theresults.
In the study, the artificial lighting system scenarios were modelled in DIALux Evo 9.2 in linewith the mean of occupants’ responses; the data for simulation programs were based on thequestionnaire results. User satisfaction, daylight availability, and main parameters of visual
comfort (natural and artificial lighting system), annual energy consumption for lighting
operating hours were evaluated. In this regard, daylight and lighting energy simulations wererun in Design Builder for 12 flats in 4 apartment blocks with different daylight patterns
throughout the year.

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Results and Conclusion
The study investigates visual comfort conditions, daylight performance, and the amount ofannual lighting energy consumption at a recently constructed residential settlement in Bursa.
The impact of residential buildings on our well-being is highlighted and discussed in thispaper with a specific focus on occupancy scenarios before and during COVID -19 lockdowns
which determine the changes in indoor lighting schedule and energy consumption patterns fora residential building site. According to the simulation results, while overall lighting energy
demand increased by 8% - 12% due to higher occupancy and lighting operation in daytime
hours during lockdowns, this consumption can be decreased by 50% via smart lighting contro l
strategies on a block scale. Even higher savings can be achieved with renewable energy
technologies which are suitable for residential buildings.
Since limited analyses have been conducted to evaluate the impact of COVID -19 lockdowns
on lighting energy use, the findings of this study is believed to be useful to improve the energy
efficiency of recently constructed residential buildings, as well as the ones at the designingphase with the goal to enhance visual comfort and a healthy indoor environment forhouseholds. The changes in living and working habits are expected to be continued even after
the resolution of the pandemic crisis. It sheds light on encouraging designers to recognize theimportance of architectural integrated lighting system decisions in cluding occupancy,
luminaire schedule and digital addressable lighting interface (DALI)/lighting control strategies
for potential energy savings.

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OP35
HOME OFFICE SURVEY IN THE SCOPE OF THE IEA SHC TASK 61, THE LIGHTINGCONDITIONS FOR STUDENTS
1

Matusiak, B.S.1, Amorim, C.2, Sibilio, S.3, Martyniuk-Peczek, J.4, Koga, Y.5
Norwegian University of Science and Technology, , Trondheim, NORWAY,
2
University of Brasilia, Brasilia, BRAZIL
3
University of Campania Luigi Vanvitelli, Aversa, ITALY
4
Gdansk University of Technology, Gdansk, POLAND
5
Kyushu University, Fukuoka, JAPANbarbara.matusiak@ntnu.no

Abstract
1. Motivation, specific objective
This paper has been developed in the scope of the IEA SHC Task 61 Integr ated Solutions forDaylighting and Electric Lighting. The Task 61 aims at developing and testing strategies andsolutions combining daylighting, electric lighting and the most suitable control systems. The
starting point for Subtask A, User perspective and requirements, is the newest research
confirming long anticipated impact of lighting on people. An adequate lighting has positive
impact on learning/work efficiency, but also mood and health. This Subtask deals with theconsolidation of available knowledge (demands, chances and challenges) on user-, activityand time-depending visual and non-visual requirements, as well as acceptance of lighting
control strategies, and includes cultural and climatic dependencies. Some of the planned
activities, however, were not possible due to the Coronavirus pandemic context. On the otherside, new challenges emerged, as for example the migration of workplaces to home offices.
This occurred both, for professionals and students, and the conditions of lighting for these
new improvised workplaces are unknown. In this context, the article presents the part of thehome office survey aiming to understand lighting conditions for students in home offices indifferent countries: Brazil, Italy, Japan, Columbia, Denmark and Poland. The paper aims also
to define current limitations of home office in providing a resilient visual environment.
2. Methods
The study has used subject survey as the main method. An internet-based survey wasdeveloped in September-November by the Subtask A experts and distributed from November
2020 to March 2021 through Google Survey across Brazil, Italy, Japan, Colombia and Poland,in the native languages of each country. The survey is organized in 3 sections, namely:“General Information”, “Lighting Condition in the whole Home Office room now” and“Description of Home Office”. With 36 questions to be answered, the survey takes about 7/8
minutes. In addition to answering questions, the participants were asked to take two pictures:the first one from the home office sitting position toward the window, aiming to show mainly
the view out, the second showing the internal home office (the desk with the closest
surrounding). The survey replies and both pictures were uploaded by participants together. Alldata was collected in excel files to be statistically analysed for correlation between selectedvariables. More than 400 students participated in the present study: 100 in Brazil, 120 in Italy,
58 in Japan, 50 in Colombia and 110 in Poland, that is a minimum of 50 stud ents from eachcountry.
3. Results
The facts to be explored from data include overall satisfaction with daylight, electrical lightand external view; and evaluation of light quality attributes as light level, spatial distribution,
colour of light, glare, shadows, reflections, and colour of surfaces. Also, information aboutmost common activities (visual tasks) in home office, presence of sun shading elements, andthe type of electric light installed in the room is given. The final question was about intenti on
to continue use of the home office after the pandemic.

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The results give important information about conditions in home offices for students. First,
most students don´t have a separate room for home office but they have arranged a desk in
one of the apartment rooms; this condition can partly explain many other results. The survey
confirms that main activities carried out in the home office can be led back to reading andwriting on screen and on paper and participating in on-line meetings and classes. The visualtasks are mainly performed using daylighting (available in many hours during the day),otherwise with electric lighting, which consists mainly of a ceiling lamp and in many cases
also of a desktop lamp. There is a high level of satisfaction with th e general lighting level inthe room and with visual environment in the room, but the students appear to be not sosatisfied with their external view from the window. Really, it became clear that the externalview plays a remarkable role in the student’s assessment.
Anyway, most students have positive attitude to their home offices, which is not surprising as
they have created them according to their own needs and preferences. Most students
answered that they intend to continue the use of the home office a fter Covid-19 period (atleast part-time), which shows human ability to adapt. This pragmatic attitude can be very
useful if the pandemic state remains longer than initially predicted or if a similar lock -down for
any reason occurs again in the future.
4. Conclusions
The correlation analysis of collected data, shows the potential causes of discomfort and/or
dissatisfaction. The results are also analysed considering cultural and climatic differences in
the participating countries, which can influence and explain some differences. Even though
the physiology of human visual system is equal across latitudes, the long -term exposure forradiation with certain features may have an impact on the human attitude for light.
Considering the proposed approach, the paper also gives insights in the potential of
considering different climatic and cultural conditions in other studies.
The outcomes can be used for generating new and comprehensive data about lighting quality
for students in home offices. Furthermore, student’s acceptability and adaptability withrespect to visual environment and lighting arrangements considering both artificial and naturallighting has been statistically evaluated, which helps to understand the visual conditions instudents home offices and to articulate the student’s needs.
The paper aims also to define current limitations of home office in providing a resilient visualenvironment
The pandemic has set back plans for in-lab and in-field experiments and inspired to think of
new and creative ways to explore indoor lighting research. It caused a shift of research
activities to remote methods reaching a wider audience and enrolling individuals with a hugeincrease of sample sizes.

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OP36
AN INTERNATIONAL SURVEY ON RESIDENTIAL LIGHTING:ANALYSIS OF WINTER-TERM RESULTS
Aslanoğlu, R.1, Kazak, J.K.2, Pracki, P.3, Yekanialibeiglou, S.1, Ulusoy, B.4
Bilkent University Department of Interior Architecture and Environmental Design, Faculty ofArt, Design and Architecture, Ankara, TURKEY, 2 Wrocław University of Environmental andLife Sciences, Institute of Spatial Management, Wrocław, POLAND, 3 Warsaw University ofTechnology, Institute of Electrical Power Engineering, Division of Lighting Technology,
Warsaw, POLAND, 4 University of Lincoln, Interior Architecture and Design, S chool of Design,
Lincoln, UNITED KINGDOM
rengin.kocaoglu@bilkent.edu.tr
1

Abstract
1. Motivation, specific objective
It is widely accepted that all indoor environments, including residential areas, have asignificant impact on people's well-being. The relationship between the building conditions ofresidential areas and human well-being becomes more significant with the outbreak of
COVID-19. From now on, our residential areas are not only shelters, but also offices, schools,
and recreational areas. The new multipurpose nature of our residential areas brought along
numerous needs to be analyzed and transformed and one of them is the study of day - andartificial lighting for the provision of high-quality living areas. The study aims to gather
respondents’ subjective assessments of the lighting conditions in their living areas, identify
the particular needs and propose lighting solutions. In order to investigate both geographical,
seasonal, and subjective differences, an international survey was formed by the auth ors, who
are professionals in the field of architecture, building design and sustainable urbanization,and lighting, to obtain a crosscutting perspective. This study focuses on the winter -term
evaluations when lighting conditions are more challenging compa red to the summer-term.
2. Methods
For obtaining international and broader data on residential lighting conditions, four countries
from different regions were selected: Sweden (Latitude: 60.1°N) from Northern Europe,
Poland (Latitude: 51.9°N) from Central Europe, the U.K. (Latitude: 55.3°N) from Northwestern
Europe, and Turkey (Latitude: 38.9°N) from Western Asia. An Internet -based survey was
distributed via email invitations and/or cross-platform messaging in November 2020-January
2021 through Google Survey in these four countries. The respondents of the study were theusers of residential buildings who could provide comprehensive insight into lighting conditions
and reside in Poland, Turkey, Sweden, and the U.K. In total, 500 participants (125
respondents from each country), aged between 18 and 66 years (47.6% females, 51.2%
males, and 1.2% who did not wish to specify gender) provided detailed self -assessments of
the lighting conditions in their living areas.
The survey asked respondents to rate the physical characteristics of the living area andlighting system, as well as lighting conditions and their satisfaction in the winter -term. Besides
providing information on demographics, characteristics of residential buildings, and day - andartificial lighting conditions, respondents were asked to answer questions about sustainability,
national lighting policies, light-related adjustments that they have made in their living areas,
and light-related changes they plan to make to have better lighting conditions. Th e gathereddata were analyzed using IBM SPSS 27.0.
3. Results
Most participants in four countries (Turkey has the lowest rate among all countries with 69.6%)
indicated that the amount of daylight in their living area is sufficient, and at least half of theparticipants (Sweden has the lowest rate among all countries with 51.2%) indicated that the
daylight in their living area is uniformly distributed. Also, there are differences between

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countries in terms of daylight satisfaction, for instance 32.0% of resp ondents from Turkey
stated that they were very satisfied with daylighting in the winter -term whereas in Poland thisrate was 16.0%. Only the 8% of the respondents from Sweden and 20% of the respondents
from the U.K. rated that they were very satisfied with their daylighting in the living area inwinter-term. Moreover, respondents from Turkey (46.4%) and the U.K. (36.0%) used artificial
lighting in their living areas between four to six hours in a winter day whereas this number ofhours of artificial lighting usage increased in Poland and Sweden to seven to nine hours in
winter-term. Not most of the respondents were very satisfied with their artificial lighting(Poland; 26.4%, Turkey; 25.6%, Sweden; 13.6%, the U.K.; 28.0%), even if the hours of usageof artificial lighting were high. Only a small percentage of respondents from all four countries
had smart lighting control systems in their living areas. Also, the majority of the respondents
from all countries (Poland; 80.0%, Turkey; 80.0%, Sweden; 89.6%, the U. K.; 75.2%) were notaware of the national policies about day- and artificial lighting.
4. Conclusions
The international survey gathered subjective assessments, identified needs and problematic
areas about lighting conditions in residential areas. The findi ngs of the study highlighted thepotential factors about day- and artificial lighting in residential lighting for providing high quality living areas. With this study, similarities and differences of residential lighting
conditions according to countries were revealed. Also, the findings of the study can be used
to build broader research and transdisciplinary collaborations.

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Session OS11
D2 – Measurement equipment
evaluation
Tuesday, September 28, 21:15–22:45

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OP37
IEA 4E SSL ANNEX INTERLABORATORY COMPARISON OF GONIOPHOTOMETERS
MEASURING SOLID STATE LIGHTING PRODUCTS – RESULTS
Ohno, Y.1, Gaudemer, J.2, Dubard J.2, Oh, J. S.3, Jeon, S.K.3,
Scholand, M.J.4, Borg, N.4, Boughey D.5, Zissis, G.6
1

National Institute of Standards and Technology, USA, 2 Laboratoire National de métrologie
et d'Essais (LNE), FRANCE, 3 Korea Institute of Lighting and ICT (KILT), KOREA, 4 IEA 4E
SSL Annex, 5 Department of Industry, Science, Energy and Resources, AUSTRALIA,
6
LAPLACE, University of Toulouse III – Paul Sabatier, FRANCE
ohno@nist.gov

Abstract
1. Motivation, specific objective
The global interlaboratory comparison (IC 2017) on measurements of solid -state lighting (SSL)
products with goniophotometers was conducted under the International Energy Agency (IEA)
4E SSL Annex and had 36 participating laboratories from 19 countries with a total of 42
goniophotometers. This comparison was organized to investigate the level of agreement inmeasurements of SSL products by various types of goniophotometers for electrical,
photometric, colorimetric, and goniophotometric quantities. IC 2017 included large mirror -type
goniophotometers and near-field type, and as well as source-rotating type goniophotometers.
The near-field type is allowed in CIE S 025 if it is demonstrated to be equiv alent to a far-fieldgoniophotometer. Source-rotating type is allowed in CIE S 025 if the effect of varying theoperating position of the luminaire is corrected or evaluated. One narrow -beam LED lamp andthree different types of LED luminaire including a s treet lighting luminaire were used for thecomparison. Analyses were conducted to compare among different types of goniophotometers
for each quantity and each artefact type to assess their equivalence. The plan of thiscomparison was reported previously (Jeon et al, CIE 2017). The comparison has been
completed and the results of the data analyses are reported and discussed.
2. Methods
IC 2017 was led by the National Institute of Standards and Technology (NIST), USA. To share
the workload of the comparison, two reference laboratories having a large mirror-type
goniophotometers (called Nucleus Laboratories in IC 2017) were assigned. They were: Korea
Institute of Lighting and ICT (KILT), Korea, and Laboratoire National de métrologie et d'Essais(LNE), France. To establish equivalence of measurements between these two laboratories, a
Nucleus Laboratory Comparison was conducted, using two sets of the comparison artefacts
and measuring all the comparison quantities. The details and results of the comparison areavailable in IC 2017 Nucleus Laboratory Comparison Report (published in IEA 4E SSL Annex
website).
IC 2017 was carried out as a star-type comparison between each participant and one of the
Nucleus Laboratories. The Nucleus Laboratories prepared and measured the artefacts,
shipped them to the participants, and measured them again upon their return. If reproducibility
was poor, the measurement of a particular artefact with the participant was repeated. The
measurements with participants were made in six rounds, two rounds by KILT and four rounds
by LNE. These measurements, and any re-measurements, were conducted between
November 2017 and September 2019.
The comparison artefacts were 1) narrow beam LED lamp (beam ang le ≈ 12°), 2) 60cm x
60cm indoor planar LED luminaire, 3) 60 cm long linear LED luminaire including small upward
light emission, 4) street light LED luminaire having asymmetric intensity distributions, with alow power factor of ≈ 0.7.

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Measurement quantities for this comparison were: total luminous flux, luminous efficacy,
active power, RMS current, power factor, chromaticity coordinates u’, v’, correlated colour
temperature, colour rendering index R a , luminous intensity distribution, partial luminous flux
(15° cone), centre beam intensity, beam angle, street-side downward partial flux, house-side
downward partial flux, uplight flux, and colour uniformity.
IC 2017 used the international standard CIE S 025 [4] (or equivalent European standard EN
13032-4) as the test method. This comparison was also designed in compliance with ISO/IEC
17043 so that it may serve as a proficiency test for SSL testing accreditation schemes aroundthe world. Further details are available in IC 2017 Technical Protocol (published i n IEA SSL
Annex website).
3. Results
All measurements and data analyses were completed. The first analysis presents
comparisons among all 42 goniophotometers for each quantity and each particular artefact.
For example, participants’ total luminous flux results were mostly within ±5% from thereference value, which was an expected number. However, RMS current showed larger
variations than expected, with standard deviation of ≈5% for the LED lamp, even thoughparticipants’ measurement uncertainties are typically 1% (k=2). The variability depended verymuch on the artefact; the standard deviation for indoor planar luminaires was just 0.5%. The
chromaticity coordinates u’, v’ were in good agreement, mostly within ±0.002 from thereference value, with a few outliers in each artefact. The results of CCT ranged from standard
deviation 26 K for artefact 1 (nominal CCT 2700 K) to 91 K for artefact 2 (nominal CCT 5500
K), which were reasonable. Note that many participants used a sphere -spectroradiometer forcolour measurements, which was allowed in the IC 2017 Technical Protocol because it is acommon practice to use a sphere-spectroradiometer system for colour measurement
combined with intensity distribution measurement with a goniophotometer.
Luminous intensity distribution data (0°, 90°, 180°, 270° C-planes) were reported byparticipants and these were evaluated together with results of centre beam intensity, beam
angle, 15° cone angle partial flux and street light partial fluxes. There were large variations in
15° cone angle partial flux; many participants were off by ≈30%, which indicated that they
mistakenly calculated flux for a 15° radius cone (twice the beam angle) rather than a 15°
diameter. For beam angle of artefact 1, two participants reported half angle (≈6 °), mistaking
the beam angle as the radius. The comparisons of luminous intensity distribution (LID) data
were difficult, as the submitted data in many cases did not match the C planes of referencelabs and the alignment angle varied. The C angle rotation was opposite in some cases (CIE
coordinate system was not followed) and/or the origin was different (not following the IC 2017
protocol). The LID curves were compared after adjusting the C planes of the participants’reported data. There were large variations in the LID curves for artefact 1 (the narrow beamlamp), as several participant’s lamp alignment was much off from the optical axis. The street
light luminaire also showed significant variations, again due to the angle alignment of theluminaire. The standard deviation of house-side downward partial flux (≈8%) is four times
larger than that of street-side partial flux (≈2%) due to alignment sensitivity.
The second analysis was for comparing the three different types of goniophotometers – mirror
type, near-field type, and source-rotating type. All 42 instruments’ results were grouped into
these three goniophotometer types and presented in graphs for each quantity and each
artefact to allow comparison among them. For colour quantities, the results of sphe respectroradiometers were separated, and compared with the results of gonio spectroradiometers. After evaluating all the graphs, no notable differences were observed
between the three types, which means that the near-field and source-rotating typegoniophotometers used in this comparison were considered equivalent to far -fieldgoniophotometers, except for a few individual cases where the differences observed may not
be attributable to the type of goniophotometer.
IC 2017 Individual Test Reports (ITRs) were issued to each participant reporting only the
results of that participant relative to the Nucleus Laboratory. In the ITRs, the participants were
informed if some problems had been found in their results. The ITR could also be used as aproficiency test report.

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The Final Report for IC 2017 is in preparation, in which all results’ graphs and data arepresented (anonymously) and the findings in details from this global comparison will bereported.
4. Conclusions
IC 2017, with 36 participants and 42 instruments from around the world, is the largest
interlaboratory comparison of goniophotometers ever undertaken. This comparison provided
precious data comparing measurements of SSL products by goniophotometers for 16 different
quantities for four different artefacts. While this comparison verified reasonable agreement insome important quantities such as luminous flux and chromaticity, it revealed a number of
specific problems in goniophotometer measurements of SSL products and indicated that moreguidance is needed in CIE S 025. This comparison also verified that near -fieldgoniophotometers and source-rotating type goniophotometers (with correction of operating
positions), in general, have equivalent accuracies to far -field goniophotometers. These results
will be useful for future improvements in metrology, standards and practice in measurementsof SSL products.

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OP38
NONLINEARITY OF CHARGE ACCUMULATING PIXEL MATRIX SENSORS USED INIMAGING LUMINANCE MEASUREMENT DEVICES
1

Ledig, J.1, Schrader, C.1, Klinger, H.1
Physikalisch-Technische Bundesanstalt, Braunschweig, GERMANY
johannes.ledig@ptb.de

Abstract
1. Motivation, specific objective
The measurement of luminance distributions is needed in many applications of lighting
systems, obtrusive lighting, and environmental monitoring, e.g. sky glow. A prominent method
is the use of imaging luminance measurement devices (ILMDs) or RGB -cameras based on animage sensor with a microelectronic pixel matrix as a key enabling technology. In such
conventional devices, each pixel consists of a photodiode operated in charge accumulating
mode; after the integration time the charge (or a corresponding voltage) is readout by
undergoing an analogue amplification and A/D-conversion (ADC).
The ADC typically covers a dynamic range of about four orders of magnitude while the signal
range is also limited by an offset and noise. The measurement of a much higher range ofluminance levels is covered by using a different integration time, this corresponds to a changeof the measurement range and therefore need to be considered for the investigation of thesignal characteristic. In most cases the integration time is assumed to act as a linear scaling
with a different dark offset signal. But regarding quantitative measurements the signal
characteristic need to be validated and characterized in detail.
2. Methods
The differential luminous responsivity (nonlinearity) of conventional ILMDs is characterized byvarying the luminance value as well as by varying their integration time (measurement range).
The considered ADC signal of the individual pixel, which passed through an analog
amplification (gain), correlated double sampling (CDS) and analogue offset, is characterizedversus the relative luminance value. To increase the observed range of charge accum ulation
at the photodiode the subsequent analogue gain was reduced, and a focus is given to thecharacteristic at luminance levels in the range of 1 cd/m².
The observed luminance level of an illuminated diffuse reflection target is varied over sevenorders of magnitude, from mcd/m² up to 10 kcd/m². These different illuminance levels are
realized by changing the distance of a light source based on a white LED from about 0.2 toabout 10 meters, thereby implicitly maintaining the relative spectral power distri bution, and by
two different configurations of a concentrating lens in front of the illuminating source. A few
higher luminance levels are represented by the light source itself or by luminance standards.
The actual luminance level is monitored by a spot luminance meter (photometer). This
monitoring photometer is based on a transimpedance amplifier that maintains a short circuit
condition of the filtered photodiode and therefore acts as a reference with neglectablenonlinearity. The absolute luminous responsivity of the monitoring photometer and the ILMD
are affected by their spectral mismatch, but their relative variation with luminance are notaffected and serve as a measure for the signal characteristic of the ILMD.
A model for the circuit of the charge accumulating photodiode inside the pixel well isdeveloped and used in transient simulations with different bias or timing characteristics. This
enables to check whether elements of the observed characteristic originate from the pixel well
diode or can be attributed to timing issues or to the analogue processing chain.

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3. Results
The ADC signal of investigated ILMDs present a characteristic relative nonlinearity versus
signal level with values of up to a few percent. For a CCD -sensor based ILMD in addition aspectral dependence of the nonlinearity is observed, with an increased nonlinearity in the red
and near-infrared spectral region.
A detailed view is given to dark offset and dark signal subtraction and their impact to thenonlinearity or to a subsequent nonlinearity correction. Transient simulations of the charge
accumulating photodiode explain the observed nonlinearity based on integration time and the
pixel well photodiode.
4. Conclusions
The circuit model and its characteristics validate, that the obs erved nonlinearity is based in
the charge accumulation principle of the image sensors rather than in the analogue
amplification or ADC. The results demonstrate that the nonlinearity of conventional image
sensors strongly depends on the measurement range (integration time).
At low luminance levels in the range of a few cd/m², that in typical ILMDs correspond tointegration times of several seconds, the nonlinearity characteristic significantly depends onthe measurement range and deviates from that at severa l 100 cd/m² and above. This need tobe considered regarding a nonlinearity correction which might have been configured for adifferent measurement range (levels of luminance) and thereby result in an error.

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OP39
METHODOLOGIES TO MEASURE SPATIAL UNIFORMITIES OF INTEGRATINGSPHERES
Maham, K., Kärhä, P. and Ikonen, E.
Aalto University, FINLAND
kinza.maham@aalto.fi

Abstract
Motivation
Integrating spheres are used in measurements of various radiometric and photometricquantities, such as diffuse reflectance, transmittance, and luminous flux in ultraviolet, visible,and near-infrared wavelength regions. In luminance and radiance measurements, spheres areequipped with light sources, and the exit aperture is used as a nominally uniform source incalibrations. In such calibrations, the nonuniformity and variation in reflectivity of the sphere
due to baffles, ports, and geometry of the integrating sphere introduce measurement errors.
To estimate the corresponding uncertainty, we scan integrating spheres for their sp atial
nonuniformities at various wavelengths. In this abstract we present three different methods formeasuring the spatial nonuniformity of an integrating sphere with low uncertainty.
Methods
The spatial uniformity of a luminance/radiance measurement sphere with a diameter of 304.8mm and an output aperture diameter of 100 mm was measured using three different methods.
In the first direct method, a filter radiometer with two apertures at fixed distances, limiting thefield of view, was used to image spots of the sphere's output, and the sphere was scannedwith XY-translators. In the second direct method, a spot luminance meter was used tomeasure the luminance of the integrating sphere, and the spot was scanned. In the reverse
method, the lamp of the sphere was replaced with a wide aperture photodiode, and a laser
beam was scanned across the sphere opening. The light paths in optics are reversible;
therefore, the signal measured by the photodiode corresponds to the spatial non -uniformities
measured using the direct method. In principle, the results obtained with direct and reverse
methods should agree, if the lamp and photodiode are small and the angular intensity
distribution of the lamp is the same as the angular responsivity of the photodiode.
The resulting spatial uniformity profiles were analyzed for two figures of merit: 1. Standard
deviation across the whole opening of the sphere which represents the uncertainty that themeasured spatial uniformity would introduce in a luminance/radiance calibration wit h thesphere, and 2. Standard deviation over a selected region, where intensity should be constant,to get a value for the statistical uncertainty of the method induced by noise.
Results
With the direct method, the spatial uniformity scan was performed wi th two diameters of thesecond aperture, 8 mm, and 2 mm, located at the distance of 635 mm from the detector
aperture of 3 mm in diameter, and 127 mm from the integrating sphere. Three wavelengths
selected by filters, 368 nm, 555 nm, and 1650 nm, were used. When the 2 mm aperture wasused at 555 nm, the signal measured was significantly low and the spatial uniformity andstatistical uncertainty were 0.48% and 0.31%, respectively. The integrating sphere's spatial
uniformity in the near infrared, 2.85%, was surprisingly worse than in visible, but the statisticaluncertainty was lower, 0.23%. When the aperture size was increased to 8 mm, the integrating
sphere's spatial uniformity and the statistical uncertainty of the method improved to 0.24%
and 0.04% at 555 nm, and to 2.16 % and 0.18%, respectively, at 1650 nm. At 368 nm, noiselevels were 0.80% and 0.90% for aperture sizes of 2 mm and 8 mm.
In the second method, the integrating sphere was scanned by focusing a spot luminancemeter on the aperture plane and the back wall of the sphere. The spatial uniformities

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measured were 0.35% and 0.41%, respectively. The noise level on both spatial maps was low:when focused on the back wall, we obtained a statistical uncertainty of 0.06 % and, when
focused on the opening of the sphere, 0.04%. The spatial uniformity and statistical uncertaintyof the second method are close to those measured with the first direct method using 8 mm
aperture at the wavelength of 555 nm.
With the reverse method, a multiwavelength setup with la ser lines at 325 nm and 543.5 nmwith a beam size of approximately 1 mm was used. The spatial uniformities measured with thereverse method had larger statistical uncertainties of 0.92% and 1.32%, and spatial
nonuniformities of 2.53% and 2.22% at the wavelengths of 325 nm and 555 nm, respectively.
The difference in spatial uniformity is partly due to a larger viewing area in the direct method,
15.5 mm with the 8 mm aperture and 5.4 mm with the 2 mm aperture, versus 1 mm with thelaser. To correct for the viewing areas, the spatial maps measured with lasers wereconvoluted to a beam diameter of 15.5 mm. Convoluted spatial uniformities had lower
uncertainties of 0.21% and 0.20% at 325 nm and 543.5 nm wavelengths, respectively. The
convolution also improved the spatial uniformity slightly to 2.47% and 2.18% at the respective
wavelengths. The remaining deviations could be attributed to coherence and the difference inangular distributions of the lamp and sphere photodiode. The effect of coherence will be
studied with a white light supercontinuum laser and a monochromator.
Conclusions
We present spatial uniformity measurements of a 12-inch integrating sphere with direct andreverse methods. We tested the effect of limiting the field of view with an aperture set at a
fixed distance. Two different secondary apertures with diameters of 8 mm and 2 mm were
tested. The integrating sphere output was also scanned using a spot luminance metermeasuring over diameters of 8 mm on the opening and 12 mm on the back wall of theintegrating sphere. With the reversed method, the sphere output was scanned using a laser
beam with a diameter of 1 mm.
The reverse method gives higher spatial non-uniformities than the direct method. Part of thedeviations are explained by different spot sizes, which was tested by convolution. The
convolution improved statistical uncertainties but did not change the measured spatial non uniformities significantly. The remaining difference can be due to issues with coherence or thedifference in angular distributions of the lamp and sphere photodiode.

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OP40
sensLAB: TESTING MOTION AND PRESENCE SENSORS FOR SMART LIGHTING
1

Stuker, F.1, Rinderer, F.1, Blattner, P.1
Federal Institute of Metrology METAS, Bern-Wabern, SWITZERLAND
florian.stuker@metas.ch

Abstract
1. Motivation
It is known that 50% of energy consumption of lighting could be saved if light is used only
when needed. In order to maintain an intelligent regulation of light, energy savings and ausage-dependent control of light can be realized in the future with the smart lighting approach.
In order to realize this automation in practice, reliable sensor technology is needed.
Confidence in the latest sensor technologies can only be strengthened if reliable sensor
parameters are available. With high-quality sensor data, the software-based planning of new
intelligent lighting concepts in outdoor or indoor areas can be realized more accurately.
Unfortunately, today's performance parameters of presence and motion sensors are hardly
comparable with each other, as in the past, each manufacturer used different measurement
methods.
2. Origin of the sensLAB Project
In order to be able to reliably evaluate and measure these sensors, sensor manufacturers
from Switzerland and Europe have formed the sensNORM associatio n and have drawn up a
standardization proposal with European Committee of Electrical Installation Equipment
Manufacturers (CECAPI). This standardization proposal was submitted to the International
Electrotechnical Commission (IEC) and has now been published as IEC 63180:2020. The
standard defines the measurement conditions and the parameters to be determined toautomatically measure passive infrared sensors (PIR sensors). In 2020, METAS decided to
implement this standard and launched the sensLAB project in collaboration with thesensNORM association.
3. Parameters of the Measuring System
To simulate the movement of a human body, dummies are mounted on linear drives are used
for automated tangential and radial sensor measurement, while the sensor is mounted o n alinear drive parallel to the radial axis on the ceiling. These dummies are equipped withheating elements to heat the head, body and legs independently. A temperature of (14 ± 1) °C
above room temperature is specified for the head, while a temperature difference of (7 ± 1) °C
is required for the body and legs.
The prerequisite for guaranteeing these constant temperature differences is the realization ofa stable room temperature, which is given at METAS with (21.2 ± 0.2) °C. In order to simulate
sensor mounting heights between 3.7 m and 18.5 m, differently scaled dummies are used. In
addition to a life-size dummy with a height of 175 cm, smaller dummies with a ratio of 1:2 and
1:5 are used. The presence range is determined with a heated and automated tes t arm, which
simulates the forearm of a person. This test arm simulates a 90° forearm movement during 1
s and allows a horizontal and, after manual modification, a vertical movement direction. In
addition to the temperature stability of the measuring room, the room dimensions must be
sufficiently large. At METAS, a room length of 15 m and a height and width of 5 m areavailable. This allows a radial travel of 12.4 m in the longitudinal axis of the centre of theroom and a tangential range of movement of ± 1.7 m perpendicular to this at the end of theroom. Furthermore, the sensor on the ceiling drive can be moved over a length of 13.6 m
beyond the tangential axis. All linear drives of the three axes can carry a mass of 60 kg canbe moved at a speed of 2 m/s and a positioning accuracy of < 2 mm is achieved.

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4. Measuring Method According to IEC 63180:2020
In a radial major motion measurement, the detection range is determined by moving on astraight line from the end of the detection range directly towards the sensor. The entire
angular range of the sensor is measured by moving the dummy towards the sensor for eachangle (typically 10° steps) in 360°. By recording the dummy's position in relation to the sensor
when triggered, the radial detection range can be displayed in a polar diagram.
In a tangential minor motion measurement, the sensor is set to a defined angle and position
and the dummy moves transversely or parallel passing the sensor (typ. ± 0.5 m in eachdirection centric to the sensor motion axis). A grid representation shows the measured
sensitivity range of the sensor. When determining the maximum tangential detection range,
the sensor position is recorded at which a movement of the tangential dummy causes a
sensor triggering. The tangential travel distance depends on the sensor position and is always± 5°. This measurement is performed at defined angular positions (typ. 10° angular steps) of
the sensor in 360° and is displayed in a polar diagram.
For the presence measurement, the test arm is moved to t he radial axis so that the centre ofrotation of the test arm is centred on the sensor axis at the sensor position 0 m. By performing
a 90° movement in the horizontal direction at the specified angle and sensor positions, a pointin the grid representation is measured. The presence measurement is repeated for a vertical
test arm movement direction and both results are represented in a combined raster diagram
representing the presence detection area
Finally, an idealized geometric shape, e.g. a circle, squar e or rectangle, is superimposed on
the measurement data and the parameters (in case of a circle, the radius) are determined forwhich, according to the standard, a maximum of 15 % of the measurement points within thegeometric shape could not be detected. All measurement results are summarized in a digital
measurement report in order to make the data available for machine -readable processing inplanning and design softwares.
4. Conclusion and Outlook
METAS has built up a world's first manufacturer-independent measurement laboratory thatcan measure passive infrared motion and presence sensors fully automatically in accordancewith the IEC 63180:2020 standard. To be prepared for the newest generations of sensors thesensLAB is currently further developed to be able to measure active sensors. These sensors
emit ultrasound or high-frequency radiation and detect and analyse the radiation reflectedfrom the environment. In addition camera based sensors are becoming more used and unified
testing procedures are necessary.

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Session OS12
D2 – Measurement of materials andsources
Wednesday, September 29, 14:00–15:30

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OP41
EVALUATION OF THE BIDIRECTIONAL SCATTERING-SURFACE REFLECTANCE
DISTRIBUTION FUNCTION FOR DIFFERENT LEVELS OF TRANSLUCENCY
1

Santafé-Gabarda, P.1, Ferrero, A.1, Tejedor-Sierra, N.1, Campos, J.1, Velázquez, J.L.1
Instituto de Óptica “Daza de Valdés”, Consejo Superior de Investigaci ones Científicas,
Madrid, SPAIN
pablo.santafe@csic.es

Abstract
1. Motivation, specific objective
The Bidirectional Scattering-Surface Reflectance Distribution Function (BSSRDF) is thefunction describing the variation of the radiance of elementary areas of a surface with respect
to a radiant flux directionally incident on that surface. Measurements of the BSSRDF are
important for characterizing the translucency of objects and for obtaining those opticalparameters affecting volume scattering. In this work, we present our BSSRDF measurements,
performed by a primary facility based on a gonio-spectrophotometer. This primary facility willallow the BSSRDF scale to be transferred to other instruments.
2. Methods
The facility is based on a gonio-spectrophotometer with spatial resolution in the collection,
spectral resolution in the irradiation, and angular resolution both for irradiat ion and collection
directions. For measuring the BSSRDF with this system, a measurement equation has been
proposed, which is based on the BSSRDF definition, but rewritten in terms of measurable
quantities at the laboratory. Specific experimental procedures have been used for determining
each quantity involved in the measurement equation, thus obtaining the corresponding
combined uncertainty of measurement.
3. Results
We have measured the BSSRDF of twelve homogeneous and translucent samples (withcontrolled values for the mean diameter of the scattering particles and their concentration).
We have acquired high dynamic range (HDR) images with a CCD camera at 40 different
measurement geometries (two incidence angles and 20 different collection directions forsampling uniformly the reflection hemisphere), and with four different wavelengths for every
geometry.
The results obtained show the different translucency levels the samples have. In general, the
BSSRDF is higher in surface elements that are inside the irr adiated area and it decreases
gradually when surface elements away from the irradiated area are evaluated. In this way, thesamples that visually seem more translucent show this decrease smoother compared to theone presented by the most transparent or opaque samples. The obtained relative uncertainty
presents a minimum located in the centre of the irradiated area, with a value around 4%(depending on the sample), which increases in surface elements outside the irradiated area,
because of the lower radiance observed in these positions.
Besides, angular distribution of the BSSRDF has been represented. These kind of diagrams
show how the light interacts with the samples, since they are related to the relative
contribution of the single scattering, the phase function of the material (angular distribution oflight intensity scattered by a particle at a given wavelength) and the scattering coefficient.
Therefore, these BSSRDF measurements must be very useful to determine these opticalproperties for the studied samples, with support of the Radiative Transfer Equation (RTE).
4. Conclusions
This work provides BSSRDF measurements traceable to the International System of Units (SI).
This quantity is very important for studying the scattering in materials, and for under standing109

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and reproducing translucency. A primary facility for measuring the BSSRDF of homogeneous
samples has been developed, characterized and tested. It will allow the BSSRDF scale to betransferred to other instruments. The complexity of BSSRDF measurem ents has been shownfor twelve homogeneous and translucent samples with different translucency levels. These
measurements must be very useful to determine the scattering and absorption coefficientsand the phase functions of the assessed materials.
Acknowledgments
This work has done within the EMPIR 18SIB03 project “New quantities for the measurementof appearance” (BxDiff). The EMPIR is jointly funded by the EMPIR participating countries
within EURAMET and the European Union. The authors are grateful to th e project PGC2018096470-BI00 BISCAT (MCIU/AEI/FEDER, UE). We are grateful to Covestro Deutschland AG
for providing with translucent samples.

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OP42
DEVELOPMENT OF A µBRDF GONIOSPECTROPHOTOMETER FOR BRDF
MEASUREMENT ON TINY SURFACES
Saha, Dipanjana, Gevaux, L., Cancès, T., Richard, A., Obein, G.
LNE-CNAM, La Plaine St Denis, FRANCE
dipanjana.saha@lecnam.net

Abstract
1. Motivation, specific objective
The appearance of an object depends not only on material, shape and lighting environment
but also on the observation distance. As an example, a textile does not look the same whenobserved a few centimetres away compared to when observed several metres away. At a very
close distance the appearance of the fibres matters, while at longer distances the full textile
pattern is dominant.
Currently textile industry is developing the “virtual prototyping” approach. The idea is to set
the optical properties of the fibre and to simulate the appearance of the full textile, providingthat the weaving scheme is known. Same approach is done in cosmetics to predict theappearance of the hair.
In parallel, 3D printing industry is progressing fast. It can be foreseen that, using different
type of resins, it will be soon possible to work on the polymer wire to transpose this multi scale
approach to the reproduction of real objects or production of 3D printed objects that will havethe same optical properties than the originals. This is particularly interesting when thinking at
the reproduction of natural objects like wool fabrics, w ood or leathers for instance.
In order to support this activity on virtual prototyping and 3D printing, LNE -CNAM, the French
Designated Institute for radiometry, photometry and spectrophotometry references, developed
a new goniospectrophotometer to perform traceable BRDF measurement on submillimetresurface.
2. Methods
The illumination light beam uses an LDLS broadband light source associated with custom
made optical system that allows illumination of the sample with a 50 µm diameter light beam
and a divergence of only 2°. It is mounted on a large rotation ring that allows to rotate aroundthe sample. The detection is composed of a commercial spectrophotometer that has been
modified in order to measure the radiance inside a geometrical extend that has a pro jectedarea of 300 µm at the sample location. The sample is hold by a 6 -axis robot arm. This systemallows to perform full BRDF measurement in the visible, on a surface with a diameter of 50µm at normal incidence. This area lengthens with a cos-1 law of the zenith of illumination due
to projected beam. To avoid vignetting issues, the zenith of illumination is limited to 70°
3. Results
The optical design of the facility allows to measure the incident flux on the sample andprovides thus absolute BRDF measurement. In order to validate the traceability ofmeasurement, an internal comparison has been done between the µBRDF gonio and theprimary goniospectrophotometer of LNE-CNAM. Results on a spectralon sample have shown
an agreement better than 5% at 550 nm. From our point of view, this agreement is good,bearing in mind that the measurement have been done on an area of 50 µm2 for the µBRDF
setup and 1 cm2 for the traditional gonio.
Further developments are already engaged using this new facility. On the model ling side,
measurements will be done on micropillar surfaces in order to compare measures and virtual
rendering models. On the metrology part, the detection has been mounted on a XY translation
stage in order to perform absolute BSSRDF measurements.

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4. Conclusions
The proceedings article and the talk will present the design of the µBRDF setup, the validation
measurements and the future works.
This work has been done in the frame of the project 18SIB03 BxDiff, that has received funding fromthe EMPIR programme co-financed by the Participating States and from the European Union’s
Horizon 2020 research and innovation programme and in the frame of the ITN ApPEARS that isfunded by the European Union’s Horizon 2020 research and innovation programme under the Marie
Skłodowska-Curie grant agreement No. 814158.

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OP43
ACCURATE MEASUREMENT OF ULTRAVIOLET LIGHT-EMITTING DIODES
Zong, Y., Miller, C.C.
National Institute of Standards and Technology, Gaithersburg, Maryland, USA
yuqin.zong@nist.gov

Abstract
There are urgent needs for accurate measurement of ultraviolet (UV) light -emitting diodes(LEDs) due to their rapidly growing applications for surface disinfections, air purifications, an dwater treatments. Currently such measurement services are either unavailable or have large
measurement uncertainties for most of labs. Compared to the measurement of visible LEDs,
the measurement of UV LEDs has special difficulties such as lack of a refe rence source(typically a standard deuterium lamp) for calibrating a measurement system, stray light errors
from a spectroradiometer, initial forward voltage anomaly of a UV LED, and fluorescence/low
throughput of an integrating sphere used for measurement of total radiant flux. Manymeasurement methods (e.g., the DC method and the single pulse method) have beendeveloped and are currently used for measurement of visible LEDs. These methods rely on
measuring LED’s forward voltage to indicate or control the junction temperature. However, UV
LEDs, especially UVC LEDs commonly have the initial forward voltage anomaly. It makes aforward voltage surge for multi-milliseconds when a measurement current pulse is applied to
the LED, and therefore the measured forward voltage is no longer valid for inferring thejunction temperature at the beginning of the current pulse.
We have developed a calibration facility for UV LEDs that overcomes the difficulties above. A
mean differential continuous pulse (M-DCP) method based on the original differential
continuous pulse (DCP) method is used for measurement of UV LEDs. A UV LED is mounted
a temperature-control mount (TCM) at a specified junction temperature. The UV LED is
operated and measured by applying a microseconds short pulse train (e.g., 10 µs) and a
microseconds long pulse train (e.g., 20 µs) so that the self -heating during each individual
pulse is negligible. To minimize the self-heating over the pulse train time, the duty cycle of thepulse train is limited to be 1% - 2 %. The measurement of the UV LED using a short pulse
train is for subtracting the rise component and fall component in the long pulse train
measurement. The differential measurement result is obtained from subtracting the shortpulse measurement result from the long pulse measurement result, which corresponds to themeasurement result of a rectangular pulse train and therefore the significant measurement
errors due to the pulse rise component and fall component of a microseconds pulse are
eliminated. The duty cycle of the differential current pulse train is determined by subtracting
the mean current of the short pulse train from that of the long pulse train. The mean current of
the pulse train is measured using a digital multimeter with a multiple -slope integrator analogto-digital converter. The measured result using the M-DCP method is then scaled to the DC
measurement result at the same junction temperature and operating current using thedetermined duty cycle value. By knowing the radiant intensity/irr adiance (or peak wavelength)of the UV LED at DC operation and adjusting (lowering) the TCM temperature, the forward
voltage of the UV LED at the specified junction temperature is measured under DC operation
when the measured intensity/irradiance at DC matches the value scaled from the M-DCP
measurement. The obtained forward voltage can be used to set the UV LED at the specified
junction temperature at DC operation.
A UV gonio-spectroradiometer on the NIST new photometry bench is used for themeasurement of UV LEDs. The UV spectroradiometer has a spectral range from 200 nm to
800 nm and its stray light error is corrected. A 1 W white LED was measured using both the
new gonio-spectroradiometer and an integrating sphere used for total luminous flux calibration
which has an expanded measurement uncertainty of 0.5 % (k=2). The measurement result
using the new gonio-spectroradiometer agrees within 0.1 % with that using the integrating
sphere. The agreement is well within the measurement uncertainty of the integrat ing sphere.

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The newly developed facility is ready for providing the measurement service for UV LEDs.
The expanded measurement uncertainty (k=2) is within 3 %. The gonio-spectroradiometer canalso be used for absolute measurements of visible LEDs and infrar ed LEDs.

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Session OS13
D1/D8 – Colour appearance models
Wednesday, September 29, 17:45–19:15

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OP44
TESTING THE PERFORMANCE FOR UNRELATED COLOUR APPEARANCE MODELS
Shi, Keyu1, Li, Changjun2, Gao, Cheng2, Luo, Ming Ronnier 1
State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, CHINA
2
School of Electronics and Information Engineering, University of Science and Technology
Liaoning, Anshan, CHINA
m.r.luo@zju.edu.cn
1

1. Introduction
Unrelated colours are perceived areas as a target been observed in isolation from any othercolours [1]. A typical example of an unrelated colour is a self -luminous stimulus surrounded
by a dark background, such as signal light, traffic lights, and street lights view ed in a darknight.
Colour appearance models aim to extend basic colourimetry to specify the perceived colour ofstimuli in a wide variety of viewing conditions [2]. Almost all models for colour appearance
have been developed to consider only related colours before [3, 4, 5], but Hunt [6, 7]
proposed a model to predict the colour appearance for both related and unrelated colours in
different viewing conditions, and he refined the original model to be used for unrelated colours,
known as CAM97u [7]. Since that, many colour appearance models to predict unrelated
colours has been developed, such as CAMFu, CAM15u, and the latest CAM20u [8].
To verify the performance of these models, various datasets were generated over the years
and only Fu dataset is used in this paper. The three models to be tested are: CAMFu,
CAM15u, CAM20u. Their performance will be evaluated by calculating the difference between
the predictions and visual data. For the three colour appearance attributes studied: brightness(Q), colourfulness (M), and hue composition (H), the coefficient of variation (CV) values arecalculated between results predicted by models and results of visual data.
2. Unrelated colour datasets
In 2012, Fu et al. investigated the colour appearance for unrelated colours , and set up adataset named Fu dataset to evaluate the performance of existing colour appearance models[9]. In the experiment, a CRT monitor was used to display colour stimuli, whose peak white
was set to have chromaticity coordinates of CIE Illuminant D 65 with a luminance of 60 cd/m².
Experiments were conducted to obtain visual data by a panel of 9 normal colour visionobservers using the magnitude estimation method, they were asked to assess each stimulus
in a darkened room in terms of colour appearance attributes of brightness, colourfulness andhue composition using the magnitude estimation method. Before the experiment, observers
were first asked to adapt in the dark room for 20 minutes, to ensure that they had adapted tothe dark room fully.
The experiment was divided into 10 phases. Each phase included 50 stimuli on the display.
Their luminance levels were ranged from 0.1 cd/m² to 60 cd/m². A piece of black cardboard
was used to mask the rest of screen colour with a hole in the middle to control the actual
angles of subtense, 0.5°, 1°, 2° and 10°.
3. Unrelated colour appearance models
Three colour appearance models were compared in this paper, including CAM15u, CAMFu
and the latest CAM20u. An introduction of each model is given below.
The CAM15u was developed based on the Ghent dataset and the CIE 10° cone fundamental.
The input to the model is the spectral radianceand attributes predicted are thebrightness, whiteness, saturation, and hue composition. Note that in the CAM15u, the input
can be tristimulus values in absolute luminance scale and a matrix transforming the XYZ tocone response signal is given.

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The CAMFu was developed based on the CIECAM02 for predicting the related colours basedon the Fu et al. dataset. In CAMFu model, the rod contribution is considered when computing
brightness and colourfulness, and the coefficientdepends on the logarithms of thevalue of the input sample and viewing angle respectively. The CAMFu model gave a better
performance than the CAM97u, the best unrelated colour appearance model at the time.
CAM20u can be considered as a refinement of CAMFu. The brightness () in CAM20u is

computed based on the computed colourfulness (to predict the Helmholtz and Krauscher
effect, i.e. two colours having the same luminance, a more colourful one will appear brighter.
The calculation of Hue quadrature and hue angle is same as CAM16.
4. Results
The above 3 models (CAM15u, CAMFu and CAM20u) were tested u sing the 3 datasets (i.e.
Gent, Derby, ZJU). The coefficient variation (CV) was used to evaluate the model’s
performance
The three models were developed from their own data. All the models can predict the four
attributes except that CAMFu cannot predict the whiteness attribute. Their performances are
summarized below.
For the Gent dataset, CAM20u and CAM15u performed equally well for predicting thewhiteness (CV=23), brightness (CV=9) and hue composition (CV=7). Bother of themoutperformed CAMFu by a large margin.
For the ZJU dataset, CAM20u performed better than CAM15u for predicting the brightness
and whiteness, while CAMFu performed the best for predicting the hue composition.
For the Derby set, CAM20u gave the most accurate prediction for all three att ributes,
brightness, colourfulness and hue composition. It outperformed the other models by a great
margin.
Overall, CAM20u performed the best, followed by CAM15u from all above tests. It is now
proposed to become a model of colour vision for predicting un related colours through a wide
illuminance range.
5. Conclusions
The aim of this study is to investigate the performance of different models for unrelated
colours, to test colour appearance models, CAMFu, CAM15u and CAM20u using the threedatasets.
By evaluating the difference between predictions of brightness, whiteness, colourfulness, huecomposition from models and visual data, the conclusion can be drawn that CAM20u showed
the best performance among the three models.

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OP45
DEVELOPMENT OF TWO-DIMENSIONAL COLOUR APPEARANCE SCALES USINGSTIMULI HAVING HIGH LUMINANCE RANGE
1

Lv, X.1, Luo, M.R.1,2
State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou,
CHINA
2
School of Design, University of Leeds, Leeds LS2 9JT, UNITED KINGD OM
m.r.luo@zju.edu.cn

Abstract
1. Motivation, specific objective
The conventional colour appearance scales are mainly based on Munsell colour order system[1] including lightness, chroma and hue. They are so popular partly because of the adoption of
CIELAB and CIELUV uniform colour spaces [2]. The more recent colour appearance models
such as CIECAM02 [3] and CAM16 [4] include not only these scales, but also their absolute
scales brightness and colourfulness to reflect the change of perception due to illumin ation.
However, these scales only correspond to one dimension of colour perception. In real life,
colour appearance of objects changes in two dimensions according to different lighting
intensities. For example, the colour appearance of an object becomes mo re ‘vivid’ underbrighter lighting condition. Here, ‘vivid’ means brighter and more colourful, i.e. change in two
dimensions. This effect can be modelled by vividness scale, V ab * proposed by Berns [5]. When
doing painting, it is typical by mixing solid pigment with white base. The more coloured
pigment, the colour becomes darker and more colourful. This is a scale of depth, D ab *proposed by Berns [5]. Cho et al carried out experiments to assess colour samples by the
British and Korean observers [6] and the visual results were used to test different colour
models and to develop new scales based on CIELAB [7] and CAM02 -UCS [3]. With thedemand for high image quality, these colour scales should be valuable to achieve morenatural and higher colour image quality. The CIE established a new technical committee 1-99
Modelling two-dimensional colour appearance scales. The term of reference is @”torecommend a set of two-dimensional colour appearance scales based on perceptual
correlates derived from colour appearance models using existing experimental data, and toprovide evidence of the value of these scales in appropriate applications. The scales include
whiteness, blackness, vividness, depth (saturation), saturation, and clarity.”This work is related to the first task (to produce experimental data). An experiment was
conducted with the following goals to 1) to accumulate reliable psychophysical data based on
stimuli of high dynamic luminance range from 40-4500 cd/m 2 , 2) to test existing 1D and 2D
scales, 3) to develop new models based on the present data.
2. Methods
The experiment was carried out in a viewing cabinet. The background colour had an L* valueof 44. Two multi-channel LED illumination systems supplied by Thouslite Ltd. were used. One
was used in the viewing cabinet having a CCT of 6500K to provide a standard environment.
The other was a back lit LED lighting transmitter to illuminate a colour chart including 24
coloured filters. A mask had the same size of each stimulus with 2 o field of view. Each colour
filter was illuminated by 5 luminance levels (90, 250, 580, 1400 to 4600 cd/m 2 ) defined bymeasuring a white colour located in the test chart.
The stimuli used in the experiment were 16 out of 24 colours on the chart. The LED
transmitter had a total of five luminance levels, so there was a total of 80 colours. All stimuli
were measured using a JETI 1211 tele-spectroradiometer, whose spectral range was from
250 to 1000 nm at a 5-nm interval. Twenty observers (10 females and 10 males) took part in
the experiment. All of them had normal colour vision tested by Ishihara colour vision test andreceived a training session to explain each impression.

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Each observer was asked to adapt in the viewing environment for one minute by looking
around the interior of viewing cabinet. Four colour appearance scales were assessed:
whiteness, blackness, vividness and depth. During the experiment, observers assessed
stimulus one scale at a time. The force choice method was used to ask observers to judge thestimulus in question to be close to white or not a white, black or not a black, vivid or not vivid,
deep or not deep for whiteness, blackness, vivid and depth perception respectively.
3. Results
The experimental results were processed, to transform the raw data in terms of "yes " and "no"to percentage.
The visual results of whiteness, blackness, vividness and depth at 5 luminance levels wereused to test 8 different scales: CIELAB L * , Berns’ vividness and depth, and saturation (s),colourfulness (M), lightness (J) and brightness (Q) of CAM16-UCS.
The results showed that 1) D ab * (-0.82) performed the best, followed by s scale (-0.68) topredict whiteness results, 2) lightness scales (L * , J) and brightness scale (Q) performed thebest (-0.72), followed by V ab * (-0.67) for evaluating blackness, 3) M performed the best (0.81),
followed by C ab * (0.76) and V ab * (0.76) to predict vividness, and 4) the lightness L * andbrightness Q performed the best (-0.84), followed by J (-0.82) to predict the depth results..
Note that Berns’ depth and vividness only gave reasonable accurate prediction. All one dimension scales could not give an overall good performance across all luminance levels. In
general, the luminance levels for 580 and 255 cd/m 2 gave better performance than the others.
Because the original model scales were mainly derived from the data accumulated in thisrange.
New models based on the ellipsoid in CAM16-UCS were developed similar to the work by Cho
et al. [7] for (Vividness (V), Depth (D), blackness (K), whiteness (W)) scales. T wo models, M1
and M2, were developed based on CAM16-UCS Q, a’, b’, and Q, M scales, respectively. It
was found that the models based on brightness (Q) were much better than those based onlightness (J). The latter can perform well for each individual light level but gave badestimations when combined the results from all levels. This can be explained that Q is anabsolute scale responding to the luminance level of light. But J is relative scale so that all test
colours were normalized to have constant colour value for all illuminations.
Model 1 performed slightly better than Model 2 as expected due to the former having more
attributes. However, Model 2 can precisely explain the relationship between one dimension
and 2 dimension attributes. We proposed to use Model 2 as two-dimension scales.
4. Conclusions
An experiment was conducted to assess colour stimuli in terms of 2 dimensional scales,
whiteness, blackness, vividness and depth under 5 HDR luminance levels. The data werethen used to test the existing scales. New scales were also developed based on the CIE
colour appearance model. Those developed based on Q and M absolute scales not only
giving accurate prediction but also describing the relationship between one - and twodimensional scales.

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OP46
CHROMATIC DISCRIMINATION THRESHOLDS OBSERVED IN CAM02-UCS AND
CAM16-UCS
Urbin, Á., Nagy, B.V.
Department of Mechatronics, Optics and Mechanical Engineering Informatics, Faculty of
Mechanical Engineering, Budapest University of Technology and Economics, Budapest,
HUNGARY
urbin@mogi.bme.hu

Abstract
1. Motivation, specific objective
The objective of our study was to observe chromatic discrimination thresholds in the
CAM02-UCS and the CAM16-UCS colour spaces.
2. Methods
In the study just-noticeable stimuli of normal colour observers measured with the Trivector
test of the Cambridge Colour Test were analysed. Chromaticity coordinates were transformed
from the CIE (1976) u’v’ diagram (the native colour space of the Cambridge Colour Test) to
the CIECAM02 and CIECAM16 colour appearance models and the CAM02-UCS and CAM16UCS colour spaces. Colour differences defined in the uniform colour spaces were calculated
and observed.
The measured data consisted of JNDs measured in 66 reference points covering the gamut ofa CRT display in the CIE (1976) u’v’ diagram. The test directions were set to the confusion
axes towards the Protan, Deutan and Tritan confusion points.
3. Results
Our results show high variance in the dE values expressed both in the CAM02 -UCS andCAM16-UCS colour spaces.
4. Conclusions
Since our input chromaticity values described previously measured just -noticeable stimuli therefore perceptually equal colour differences - we assumed that our data would show equal
colour differences in the uniform colour spaces.
However, the discrimination thresholds transformed to CAM02-UCS and CAM16-UCS showthat colour differences increase towards the chromaticity of the adapting light.

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OP47
REFERENCE WHITE IN A COMPLEX VIRTUAL REALITY ENVIRONMENT
Wu, C., Ou, L.
National Taiwan University of Science and Technology, Taipei, CHINESE TAIPEI
ching052486@gmail.com

Abstract
1. Motivation, specific objective
Perception of colour appearance depends strongly on the reference white. It may be difficult,however, to determine the reference white when there are multiple white objects with various
luminance values here and there in the experimental space. The issue is particularly essential
in virtual reality (VR) where the user can freely view and interact with objects in every cornerof the VR environment with a complex scene setting. Is reference white determined by thebrightest white object in the entire environment no matter how far this white object is locatedaway from the test colour? To solve the issue, we conducted 3 colour appearance
experiments in VR and in a real room, as described in the following.
2. Methods
Experiment 1 was conducted in a real room. Experiments 2 and 3 were both conducted in VR
using a mobile head-mounted display (HMD). Note Experiments 1 and 2 were conductedusing conventional magnitude estimation method, i.e. a reference white and a reference
colourfulness were both provided in the experiment. In Experiment 3, instead of showing
these reference colours, two candidates for reference white were presented, one loca ted near
the test colour and the other located outside the viewing field for the test colour. A panel of 20
observers participated in each of the experiments.
The room used in Experiment 1 was a 3.5m (width) x 2.5m (depth) x 2.3m (height) space
enclosed within 3 grey walls, lit by 3 LED lamps with a CCT of 6500K. In front of the main wall
was a grey table, on which a variety of objects were presented, including building blocks,
plaster cubes, coloured boxes and a GretagMacbeth ColorChecker. Several wooden b oxes
were on the floor near the table. On the main wall were a test colour, a reference white(luminance = 230 cd/m 2 ) and a reference colourfulness, all of which were matt paper patchesof Practical Coordinate Color System (PCCS), 7cm x 12cm in size. Twenty test colours wereused in this experiment, covering a wide range of hue, lightness and colourfulness. In theexperiment, the test colours were presented one at a time in random order. Observers wereasked to visually assess hue, lightness and colourfulness of each test colour using themagnitude estimation method based on the reference white and the reference colourfulness.
In Experiment 2, each observer wore a mobile HMD, consisting of a VR headset “AiboxVR
Shinecon Deluxe II” and an iPhone 6s Plus, to assess colour appearance of 29 test colours in
VR. The iPhone 6s Plus was set to have a display luminance of 28.9 cd/m 2 . The VR
environment was a simulation of the room used in Experiment 1 , including test colours, areference white, a reference colourfulness on the wall and the other stuff on the table and on
the floor. Experimental methods were the same as in Experiment 1 .
In Experiment 3, the VR environment was the same as in Experiment 2 , except there was no
paper patches of reference white or reference colourfulness on the wall, and that two white
plaster cubes were presented as candidates for being regarded as the reference white, one
located near the test colour and the other located outside the viewing field of the observerwhen looking at the test colour. The former plaster cubes had a luminance of 4.7 cd/m 2 andthe latter 28.1 cd/m 2 . The observers were asked to look around in the VR environment before
starting the experiment to ensure they have seen both white cubes. During the visualassessment, the observers were asked to give a value between 0 (black) and 100 (white) forlightness. For colourfulness, the observers were also asked to give a value between 0121

CIE 2021 - Abstract Booklet(achromatic) and 100 (the upper limit). The 29 colours used in Experiment 2 were again usedas the test colours in Experiment 3.
3. Results
According to results of Experiment 1, high correlation was found between perceived hue
quadrature and CIECAM02 H, with a coefficient of variation (CV) of 7; high correlation was
also found between perceived lightness and CIECAM02 J, with CV = 18; and high correlation
was found between perceived colourfulness and CIECAM02 M, with CV = 29. The results
show good predictive performance of CIECAM02 for using conventional methods.
Results of Experiment 2 also show good predictive performance of CIECAM02 for VR colours,with CV = 10 for hue, CV = 25 for lightness, and CV = 36 for colourfulness. Although thesevalues look slightly larger than those for Experiment 1, the results suggest that colour
appearance in VR is comparable to that in a real environment.
From results of Experiment 3, CIECAM02 values were first calculated based on luminance of
the white plaster cube located near the test colours, and good correlation was found between
perceived and predicted values, with CV = 21 for hue, CV = 32 for lightness and CV = 39 forcolourfulness. CIECAM02 values were then calculated based on luminance of the white
plaster cube located far away, and the results show CV = 24 for hue, CV = 59 for lightness,
and CV = 73 for colourfulness. It is clear that the white plaster cube located near the test
colours was a more reasonable reference white than the one located far away, although thelatter was much brighter than the former in the entire environment.
4. Conclusions
Experimental results suggest that colour appearance in VR is comparable to colour
appearance in a real space. In a complex VR environment, the brightest white object is notnecessarily regarded as the reference white especially when it is located far away from thetest colour. The brightest white object needs to be located within the viewing field for the test
colour in order to be regarded as the reference white. The results can help clarify issues invisual perception of coloured objects in VR.

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Session OS14
D3 – Lit environment
Wednesday, September 29, 17:45–19:15

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OP48
QUANTIFYING SPACIOUSNESS FROM COMBINED DATA OF LUMINANCE ANDDISTANCE CONSIDERING THE LOCATION OF BRIGHT SURFACES
1

Miyake, H. 1 , Okada, M. 2 , Yamamoto, T. 2 , Yamaguchi, H. 3 , Yoshizawa, N. 2
Arup, Tokyo, JAPAN, 2 Tokyo University of Science, Chiba, JAPAN, 3 National Institute forLand and Infrastructure Management, Ibaraki, JAPANhiroyuki.miyake@arup.com

Abstract
1. Motivation, specific objective
As spaciousness is an important factor for users of space, it is useful to study the perception
model to develop tools for measuring spaciousness and to develop methods to estimate thespaciousness expected in the design phase. Previous studies show that light affects theperceived spaciousness of an interior space and the target of this study is to further
understand the mechanism of the spaciousness perception related to the lighting environment.
In our previous report, as the result of a subjective experiment in a living room, it was
revealed that the quantity of light has positive correlation with spaciousness. Moreover, byanalysing the combination of data of luminance image and the distance to each surface fromthe observer, the uniformity of lighting and the localization of bright area in the space also
affects the spaciousness. For further study, it was necessary to conduct more experiments
involving various lighting conditions with different lighting fixtures and different localization oflight using flexible control system. The analysis method was also necessary to be developed
to take into consideration the spatial unevenness of light and the luminance level of each typeof elements such as walls, floors, and ceilings.
2. Methods
To examine more cases of different lighting conditions, three spaces are p repared withdifferent fixtures (baselight / downlight / spotlight) and with system to control fixturesindividually to illuminate different areas and different parts of the room (wall / floor). The
experiment’s focal point was asking the subjects in magnitude estimation (ME) method theperceived spaciousness of the spaces with different lighting scenes compared to thespaciousness with standard reference scene.
The first experiment was conducted in a 150.9 m 3 rectangular room without furniture. Threetypes of lighting methods were installed. The first method was ceiling -recessed base lightingwith diffusing light distribution to illuminate both walls and the floor without highlight. The
second method used ceiling track-mounted wide beam spotlights oriented toward theperimeter of the room to mainly illuminate the walls around. The third one also used similar
spotlights but oriented downwards to illuminate the floor. The lighting control system enabled
to realize several uneven lighting distribution patterns by dimming-controlling each fixture. For
example, the subject’s side of the room to be bright in a pattern, the other side to be bright inanother pattern, and both sides to be bright while the central part to be dark yet anotherpattern. In addition, we also changed the physical room size with separator at the middle ofthe space to estimate the effect of changes of both lighting environment and physical volume
in the same time and to evaluate the relation between them. 72 scenes were prepared for 17
participants.
The second experiment was conducted in a 55.6 m 3 rectangular living room with furniture with
12 subjects. This was the same room as the experiment in our previous report, but withadditional two types of lighting fixtures and control system design ated for this experiment,
more various lighting scenes are prepared for the new experiment. One method was linear
ceiling-mount base lighting with diffusing light distribution, while the other method was ceilingtrack-mounted wide beam spotlights oriented downwards. 19 scenes were prepared for 12
participants.

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The third experiment was conducted in a 168.9 m 3 rectangular room without furniture. Existing
two types of lighting fixtures and dimming system were used. One was ceiling recessed
fluorescent batten base lights and the other was wide beam ceiling-recessed downlights. 5
scenes were prepared for 19 participants.
3. Results
Comparing the lighting scenes of which only the dimming levels are different but the methodof lighting and the spatial light distribution are the same, the results reinforced the previous
conclusion “the more light there is, the more spaciousness is perceived”. However, comparing
different lighting methods and distribution of light is not that simple.
Regarding the difference of lighting method in the first experiment, comparing the scenes inwhich the whole room is illuminated evenly without dark area, the spotlights oriented to wall
has more positive effect to spaciousness compared to the other methods. The others, thebase light and spotlights oriented to floor did not show significant difference.
To consider the spatial distribution of light, there are two factors. The first one is thehorizontal localization of light and the second one is the balance of luminance level ofdifferent types of elements of the room. Regarding the first factor, when the localization oflight is more uneven with significant bright area and dark area, the spaciousness becomes
smaller. Looking into the second factor, the balance of luminance level of room e lements, wehave separated the luminance and the dimension data into ceiling, side walls, front wall, andfloor, and found that the side wall brightness compared to the whole room brightness havepositive effect to the spaciousness.
4. Conclusions
From the result of the experiments we have revised the estimation formula of spaciousness
with two parameters, quantity of light and visible volume.
For this quantification of light, we created a value “area weighted average luminance” bycalculating the average of the luminance considering the area of the corresponding surface.
This value is highly correlated with the average illuminance of space but better than it for the
calculation model because the luminance is a value which can be directly observed by theparticipant while the work plane illuminance is not.
To quantify the volume, we used the visible volume from the participants. The visible volume
is better than the whole room volume, as it can be observed directly by the participants and it
can take into account the obstacles such as column, beam, and furniture. The unevenness oflight can be reflected to this value by subtracting the volume of very dark spaces.
In addition, the balance of the luminance between different types of the room element can beused to make the estimation formula’s residual error smaller.

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OP49
A NEUROPHYSIOLOGY-BASED MODEL TO ESTIMATE VISIBILITY IN ACTUAL
LIGHTING ENVIRONMENT
1

Yoshizawa, N.1, Shida, H.2
Tokyo University of Science, Chiba, JAPANyoshizawa@rs.tus.ac.jp

Abstract
1. Motivation, specific objective
Brightness, glare, visibility are the fundamental factors for explaining the lighting environment,
and various quantitative indexes for these have been made in such a manner that directly
finds the formulae that best match the numerous subjective evaluations. Recently
neurophysiology-based models have been paid attention as the complementary or alternative
methods to these conventional indexes. In this paper we will introduce the normalization andgain control models, which are generally-accepted theories in the visual information
processing, to estimate the visibility (in this research, the term “visibility” includes threeviewing regimes of subthreshold, suprathreshold, and saturation), and verify the validity ofthis algorithm by comparing with the subjective evaluation in the experimental room. The
important thing is that the basic algorithm should be open and discussed publicly. It is
indispensable to use these kinds of evaluation/estimation methods in the lighting standards o r
actual lighting design processes.
2. Methods
Visibility can be explained based on the edge detection of objects in the environment. In ouralgorithm, input data is luminance distribution in the visual field captured by CCD/ CMOS
sensors at the viewpoint, and three phases in the early visual information processing fromretina to primary visual cortex (V1) are built up in the algorithm. Optical processes from pupil
to retina are not taken into consideration in this research. Visibility here is limited to the foveal
vision under photopic luminance levels.
The outline of the algorithm is as follows. Setting parameters will be elaborated in detail in the
final paper.
1) Retina: Based on the size of a receptive field of a neuron, local luminance ( the weighted
mean luminance in the patch) is first calculated. It corresponds to the retina’s smoothing
function on the entire input image. Next, local contrast is calculated using Difference ofGaussian (DoG) filters, which mimic the antagonistic center-surround receptive fields in theearly neural processing. This process models the luminance gain control and local light
adaptation mechanism.
2) Lateral geniculate nucleus (LGN): After the visual information is relayed from the retina to
LGN, contrast gain control mechanism comes into the operation, and it is calculated by thenormalization formulae using the excitatory and suppressive responses. This process can
mimic the phenomena such that high-contrast responses are saturated in the visual
processing.
3) Primary visual cortex (V1): There are simple-cell and complex-cell receptive fields inprimary visual cortex, which relate to the edge detection, and their profiles can be modeled by
the Gabor filters. By referring to the previous data in the neurophysiology, we have chosen
the parameters for the shape, spatial frequency domain, directional selectivity, and phase,and the responses of simple-cell and complex-cell receptive fields are calculated respectively.
The phase for the simple-cell receptive field is set to be π/2, that is odd filter, for focusing on
the edge detection. Finally, to correspond to the suprathreshold visibility, the responses ofsimple cells are normalized by the integrated responses of complex cells calculated based on
the energy model.

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To verify the validity of this algorithm for applying it to the actual lighting environment, we
conducted a subjective experiment using an architectural mock -up model with a pseudo
window. The indoor space of the model was 1400mm in width, 3000mm in depth, and1400mm in height. A window of 1100mm in height and 700mm in width was cut on the front
wall to observe simple figures in the outside with a uniform bright background imitating thesky. Three levels of sky luminance (2500, 1200, and 700 cd/m 2 ) were reproduced byarranging 24 fluorescent lamps side by side behind a diffusion filter, and two levels of spatial
brightness for the indoor space were prepared by arranging four fluorescent lamps. A singlepane glass, a smoke glass, tinted glasses (red, blue, green), and w indow screens(18mesh/black, 18mesh/gray, and 24mesh/black) were installed individually in the openings
for each experimental condition, and a translucent vertical rectangle with different
transmittance (93.0%, 48.0%, 23.5%) was set up as experimental stimulus in the outside: thatis, various edges with wide range of different strength were produced between the vertical
rectangles and the sky background. The subjects were 12 students in their 20s with a visualacuity of 0.7 or higher. They evaluated the visibility of the edges of the rectangle in six-point
scale: 1: not visible at all, 2: just noticeable, 3: somehow visible, 4: fairly visible, 5: quite
visible, 6: highly visible. Luminance distribution was measured for every condition using
CANON EOS 5D mark III+TAMRON SP 45mm F/1.8 from the viewpoint of the subjects.
3. Results
The simple linear regression analyses were applied between the subjects' evaluations(objective variable) and the calculated values by this algorithm (explanatory variable), and ahigh coefficient of determination of 0.96 was obtained for a single -pane glass condition. The
coefficient of determination was also high enough (more than 0.9) for all the other conditions.
The result showed that the algorithm in this research could estimate the visibility of the simple
objects in the experimental space with a pseudo window with great accuracy.
4. Conclusions
A neurophysiology-based model for estimating the visibility was developed, and its validity
was verified through comparison with the subjective evaluations. There still remains lots ofunsolved issues in the visual information processing, and there are several options that canbe selected for the basic models and Gabor filter parameters, therefore, it is desirable andnecessary to publicly discuss various algorithms and clarify their reliability based on theverification results under various situations.
In this research the odd Gabor filter was used for the edge detection, whereas there is apossibility that basic data to estimate brightness and glare in the environment could beobtained through the bar detection using the even Gabor filter and the normalization model. In
future work the basic parts of the calculation algorithm will be developed so that it can beapplied to any factors for explaining lighting environment.

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OP50
EFFECTS OF LUMINOUS COLOUR SHIFT Duv ON COLOUR PREFERENCE
Koyama, M., Mochizuki, E.
JAPAN
s16b1061ee@s.chibakoudai.jp

Abstract
1. Introduction
Dimmable and tone controllable LED lighting can express various luminous col our and has
been becoming popular. In the most general toning process that combines the output of thetwo different colours of LED, sometime the chromaticity point become far from the Planckian
locus (hereinafter referred to as duv). Luminous colour greatl y influences the spatial
impression. It is important to identify the effects of chromaticity shift during the toning process
on spatial impression.
In this study, subjective experiment was conducted to identify the combined effects of theinterior style, correlated colour temperature (CCT) and duv on spatial impression of livingroom. This paper reports the results of analysis of the effects of chromaticity shifts of thesurface colour of each interior material on the spatial preference.
2. Methods
2.1 Experimental apparatus
Two same models, the reference model and the test model, of 1/5 scale assuming typicalJapanese living room (inner dimensions W: 900 mm x D: 900 mm x H: 480 mm) wereprepared. Lighting fixture made with 6 LED lamps (Philips hue full colour) was settled at the
top of the model. The inside of the model was illuminated by diffused light from the lighting
fixture through an opening with a sheet of tracing paper whose size was 120 mm in the
diameter on the ceiling.
Several furniture such as table, sofa, rug, shelf, and etc. were settled in the model to help the
subjects to image the actual living room easily. The interior style of the test model had two
conditions, the modern style based on achromatic colours and the natural style based onwooden colours. The conditions of the two models were the same except for duv, i.e., theinterior style and CCT of the luminaire were the same.
The subjects looked into the model though the peephole (W:160mm×H:70mm) with the heightof 280 mm at the centre assuming he /she was sitting in a chair.
2.2 Experimental conditions
All 14 lighting conditions combined with two levels of the CCT (2700K/5000K) and 7 levels ofduv (+0.02 to -0.04) were presented. The average illuminance on the floor of the model was
set 200 lx in average (measured at 9 points, T & D TR-74Ui), which was in accordance withthe recommended level for residential living room by JIS Z 9110:2010. The CCT of theluminaire in the reference model was set at duv0.
2.3 Experimental procedure
The subject adapted his/her eyes to 200lx of the vertical illuminance at their eyes for 180
seconds before the experiment. Then he/she was asked to observe the reference model for
60 seconds, and after that, he/she was asked to move their eyes to the test model. The
subjects evaluated colour appearance of each furniture in the test model and colour
preference of the entire space of the test model comparing with those in the reference model(comparison evaluation). The subjects were allowed to observe both models repeatedly.
Subsequently, the subjects observed the test model only for 30 seconds, and evaluated theimpression of the lighting environment by SD method using 15 adjective pairs (impression

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evaluation). A series of the experiment (comparison evaluation and impression evaluat ion)
was repeated 7 times with the other duv under the same CCT. After a 7 series of theexperiment with 2700K/5000K was over, the same procedure with the other CCT was
repeated again. 14 conditions (2 conditions of the CCT and 7conditions of the duv) wereexperimented within 2 hours in a day. The same procedure of the other 14 conditions withanother interior style was conducted on another day to avoid the subjects’ fatigue. Twenty
university age students with normal colour vision (average 22.1 years old) participated in theexperiment as the subjects.
3. Results
3.1 Difference in chromaticity of the inner surface of the model due to duv
The chromaticity of the surface of each interior material under each condition was measured
from the subjects' viewpoint (JETI, Specbos1201). There was a tendency that the chromaticity
shifted toward the yellow-green side with positive duv and toward the red-violet side withnegative duv. Especially in the case of modern style with 2700K, the difference in thechromaticity of the wall due to duv was large.
3.2 Perception for difference in chromaticity of the inner surface of the model
In both interior types, the percentage of the subjects who perceived the colour difference
between the reference model and the test model tended to increase as the distance between
the chromaticity coordinates with duv0 and with any duv increased in the case with 5000K,
while that did not necessarily happen in the case with 2700K. This tendency was stronger as
the chromaticity of the interior material shifted toward the red-violet side at 5000K, especiallyin the case with the modern style. However, the percentage of the subjects who perceived thedifference in colour of each interior material at 2700K was higher than that at 5000K.
3.3 Colour preference for the entire space of living room
In the case with modern style, the subjects preferred the colour for the entire space more withthe larger positive duv at 5000K and they preferred less with the larger duv both on positive
and negative sides at 2700K. On the other hand in the case with natural style, the subjects
preferred the colour for the entire space most at duv0, except for the condition with duv -0.04
and 2700K.
4. Conclusions
According to JIS Z 8725: 2015, the CCT with duv in the range of ±0.02 i s categorized as thesame regardless of the colour temperature. However, not only the perception of colour
difference but also the colour preference for the entire space is effected by duv and also by
CCT. It is necessary to reconsider the recommended rang e of duv that can be categorized as
the same CCT considering colour preference.

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OP51
THE EFFECT OF LIGHTING ENVIRONMENT ON FACIAL EXPRESSION PERCEPTION IN
VIDEO TELECONFERENCING
1

Suzuki, K. 1, Takeuchi, Y.1, Heo, J. 1
Shimane University, Matsue city, JAPAN
kei24012401@gmail.com

Abstract
1. Motivation, specific objective
In this study, we investigated whether manipulating the lighting environment in a video
teleconference would change the readability of facial expressions. Currently, the newcoronavirus (COVID - 19) is epidemic in many countries around the world, and companies andeducational institutions have recommended telecommuting and online lectures. As a result,attention on video conferencing systems, including ZOOM, Teams, and Webex, has increased,
and opportunities for non-face-to-face communication have increased dramatically over the
past year.
However, in video teleconferencing using these systems, there are some comments such as"it's hard to hear the other person's voice," "conversations don't mesh due to delays," and "it'shard to read facial expressions, making communication difficult". Of these opinions, thereadability of facial expressions is particularly important for making a good impression at job
interviews and business meetings. In general, it is said that the readability of facial
expressions can be improved by the angle and direction of illumination, colour temperature,and other factors. However, these findings are based on the assumption of face -to-facecommunication, and it is not clear whether they can be applied to non-face-to-facecommunication situations such as video teleconferencing as well. Therefore, it is necessary toinvestigate whether it is possible to make the impression intended by users in video
teleconferencing as well, using a simple method of preparing the lighting environment.
2. Methods
In the experiment, a total of 20 people, 10 males and 10 females, were asked to evaluate theirimpressions of a video conference conversation filmed under multiple lighting condit ions. The
video was filmed in a dark room to eliminate the effects of ambient light, and a 30 -second text
was read by a seated adult male with his chest and upper part of the body visible. Four typesof sentences were selected from the continuous speech database created by the Sound
Resource Consortium of the National Institute of Informatics. The lighting conditions wereselected three colour temperatures conditions (3000K, 4200K, and 6000K) and four lighting
directions conditions (90 degrees forward, 45 degrees diagonally forward, 45 degrees
diagonally backward, and 90 degrees backward), for a total of 12 conditions. The illuminance
was adjusted to 600lx for all conditions using an illuminance meter. The text to be read andthe lighting conditions were presented in a random order for each subject. For impression
evaluation, 20 adjective pairs related to the impression of facial expressions were selectedbased on previous studies, and graded on a 7-point scale using the SD method. The
evaluation time was set at 120 seconds after the video presentation.
3. Results
The results of the impression evaluation were showed that when comparing only theillumination direction conditions, the "90 degrees forward" and "45 degrees diagonallyforward" conditions were higher than the "45 degrees diagonally backward" and "90 degrees
diagonally backward" conditions for all items.
Comparing the results by colour temperature, the difference between the "90 degrees
forward" and "45 degrees diagonally forward" conditions and the " 45 degrees diagonally
backward" and "90 degrees diagonally backward" conditions was the largest for the 3000K

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colour temperature, and the difference for each evaluation item was small. On the other hand,when the colour temperature was 4000K, the differenc e between the "90 degrees forward"
and "45 degrees diagonally forward" conditions and the "45 degrees diagonally backward"
and "90 degrees diagonally backward" conditions was small, and the difference for each
evaluation item was large.
As a result of factor analysis of the 20 items used for impression evaluation, four factors wereextracted: "clarity," "dynamism," "naturalness," and "health" (maximum -likelihood method,
Promax rotation). The results of two-factor analysis of variance for each factor, with c olour
temperature and lighting direction as independent parameters, showed a significant differencein the main effect of lighting direction, with the "90 degrees forward" and "45 degrees
diagonally forward" conditions is higher than the "45 degrees diagon ally backward" and "90
degrees backward" conditions for all four factors. On the other hand, there was no significant
difference between 45 degrees and 90 degrees in both the "forward" and "backward"
conditions.
One-factor analysis of variance with colour temperature as the independent parameter was
conducted for each evaluation item to confirm the effect of colour temperature. As a result,significant differences were observed in the evaluation items of "hard -soft" and "cold-warm",and the item of "hard-soft". "hard - soft" item is higher in the 3000K condition than in the4200K condition, and the "cold-warm" item is higher in the 3000K, 4200K, and 6000K
conditions, in that order.
4. Conclusions
These results confirm that the direction of illumination proje ction has a significant effect on
the viewer's perception of facial expressions in video teleconferencing, and that projecting
illumination from the front gives a more favourable impression. It was also confirmed that thelower the colour temperature of the lighting, the more favourable the impression, although theeffect was smaller than the direction of lighting projection. Therefore, it can be said that whenusing video teleconferencing, it is possible to create a better impression simply by taking thetime to change the seating position, lighting position, or lower the colour temperature if thelighting is dimmable.
In this study, experiments were conducted by using ceiling lights, which are widely used inJapanese homes, but the effects of using spotlights have not yet been clarified. In particular,
although the results of this study did not show any difference by the angle of the lighting
placement, the use of spotlights may emphasize the three-dimensional effect and show thechange in impression by the placement angle. Therefore, it is necessary to study the situation
using multiple light sources including spotlights in the future.

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Session OS15
D4 – Road lighting metrics
Wednesday, September 29, 17:45–19:15

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OP53
IMPACT OF QUALITATIVE AND QUANTITATIVE METHODS ON THE EVALUATION OF
STREET LIGHTING UNIFORMITY*
1

Wänström Lindh, U.1, Jägerbrand, A.K.2
Jönköping University School of Engineering/Department of Construction Engineering andLighting Science, P.O. Box 1026, SE-551 11 Jönköping, SWEDEN
2
Halmstad University, School of Business, Engineering and Science, Department ofEnvironmental and Biosciences, Rydberg Laboratory of Applied Science (RLAS),
P.O. Box 823, SE-301 18 Halmstad, SWEDEN
ulrika.wanstrom-lindh@ju.se, annika.jagerbrand@hh.se

Abstract
1. Motivation, specific objective
Lighting uniformity is considered highly important for traffic safety and pedestrian reassurance.
Followingly, it is one of the major criteria which must be fulfilled for sufficient road lighting.
However, the need for lighting uniformity for drivers and pedestrians may differ. Yet, the needfor pedestrians is often assumed to be met in mixed traffic environments when the lighting
uniformity requirements for vehicle traffic are fulfilled. Uniformity for drivers is commonly
evaluated based on quantitative data, such as overall luminance uniformity, but methods forevaluating uniformity from other road user’s perspective is currently somewhat lacking.
This paper discusses assessments of street lighting uniformity with the use of qualitative andquantitative methods, and the possible consequences for the lighting design and the road
users.
In this paper, two field studies are discussed. Field study 1 describes three pedestrian streetswith similar lighting, but with different topographical and landscape conditions are visuallycompared with each other. In field study 2, the uniformity was evaluated and compared
between seven streets for motorized traffic and seven streets for pedestrian and bicycle traffic.
2. Methods
With this article, we wish to exemplify the increased value of using mixed methods whenstudying outdoor lighting. We use the convergence design and the imbedded design method
to study lighting uniformity using both qualitative and quantitative methods.
Field study 1: Non-uniformity caused by landscape variations
Three pedestrian streets in Jönköping, Sweden, were chosen for the study. The LED
luminaires were similarly equipped. The character of the street space differed more than thelighting equipment. The pedestrian roads were similar in size but differed in how open or
closed the surrounding space were. It is also important if there are trees and bushes around,and if the roads were straight, or curved and hilly.
The following process was inspired by experimental phenomenology. The intention was bothto observe the light situation as such, but also to grasp the whole surrounding space. Thisobservation was performed by the researchers and lasted for approximately one hour at eachsite.
Phases on the visual observations at the sites:5) Visual observation – the overall impression6) Describe and sketch the environment, save interpretations for later
7) Discuss associations to functions and spatial elements
8) Find characteristic patterns

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9) Discuss preferences and prejudices
10) Compare with the other sites
Field study 2: Variation in uniformity in street lighting for motorized traffic and pedestrian andbicycle traffic
Fourteen different roads with LED lighting were chosen for this study. For each street,average road surface luminance (L), overall luminance uniformity (U o ), and longitudinalluminance uniformity (U I ), and minimum luminance (min) were calculated based on
measurements performed by the LMK Mobile Advanced imagining luminance photometer. L,
U o , U I , and min were assessed and analysed for differences between motorized andpedestrian and bicycle streets, and between the streets.
3. Results
Field study 1: Non-uniformity caused by landscape variations
It was not expected that the urban surrounding had a higher impact on the vi sual impressionof uniformity than the lighting as such. Surprisingly, the street with the largest pole distanceand with the most curved and hilly landscape surrounded by dark pine trees was notexperienced as non-uniform. A possible explanation can be that we, by tradition, are not used
to uniform light in such a landscape. Another pedestrian street, in an open landscape, next toa car road, was experienced as very uniform, since it expressed monotony; nothing special
caught the gaze. The third pedestrian street had closer pole distances, it was flanked bybushes and foliage. The street was uniformly lit, but it still felt non -uniform. This relates to theheavy foliage casting shadows. The impression was varied and lively. The vertical lightreflected from the vegetation gave a bright impression.
Field study 2: Variation in uniformity in street lighting for motorized traffic and pedestrian andbicycle traffic
Streets for motorized traffic had a mean L of 0.62 (SD=0.071) cd/m 2 , U o of 0.55 (0.11), and U I
of 0.62 (0.100) and 0.64 (0.075), and minimum value of luminance was 0.34 (0.071) cd/m 2 .
Pedestrian and bicycle streets had an L of 0.45 (0.097) cd/m 2 , U o of 0.35 (0.071), and U I of
0.305 (0.073) and 0.309 (0.073), and the minimum value was 0.17 (0.054) cd/m 2 . All sevenstreets for motorized traffic had values of U o above 0.40. Only two of seven pedestrian andbicycle streets had U o above 0.40, whereas five streets had U o below 0.32. There was a large
difference in L, U o , U I and min between the motorized streets and the pedestrian and bicycle
streets, and this was also supported by analyses of the effect size.
4. Conclusions
From field study 1, we see the importance of looking at the illuminated road in the entire
spatial context. Field study 2 shows the need for recommendations based on a holistic view
where several road user types are taken into account based on their different needs. Bothfield studies support the need to focus more on the pedestrian's perspective.
With only a quantitative method the whole spatial context will usually not be considered.
There are many external factors that interact with the perception of uniformity in urban space.
Such factors which can be considered in light planning are vertical reflective surfaces(vegetation), the width and openness of a street, and also the topography and curvature of thestreets.
The motorized streets in general have higher uniformity compared to the pedestrian andbicycle streets. The pedestrian and bicycle streets have very low uniformity and minimum
values of luminance, which demonstrates that a high uniformity is probably not priorit ized in
the lighting design and planning stage. If the uniformity is very low, this might have negative
consequences for the users’ need. For example, a bicyclist may not detect hazardous objects
on the road surface.
The road lighting should be planned from a holistic and sustainable perspective. In thecontext of this study, it translates into taking serious considerations of various road user andtheir interactions with the whole urban space into account.

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OP54
NUMERICAL-ANALYTICAL MODEL OF THE LUMINANCE FACTOR OF AN ARBITRARYSURFACE
1

Basov, A.Y.1, Boos, G.V.2, Budak, V.P.1, Grimailo, A.V.1
Russian Lighting Research Institute named after Sergey Vavilov (VNISI), Moscow , RUSSIA,
2ILEC “BL GROUP” LLC, Moscow, RUSSIA
callia12@rambler.ru

Abstract
1. Motivation, specific objective
Road safety at night is determined by the luminance distribution created by asphalt-concrete
pavements. Experimental determination of the bidirec tional reflectance distribution function(BRDF) is impossible without a mathematical model of typical road surface materials. The
presence of the model enables one to classify samples and define the luminance factors or
coefficients for arbitrary angles. To solve this problem, the authors propose both an analyticaland a numerical model of the luminance factor, which pave the way for modelling thereflection from real surfaces with high accuracy for any incidence or observation angles.
2. Methods
The analytical model of the luminance factor is based on a plane-parallel scattering layer. In
this case, the substrate of the layer reflects diffusely, and the upper bound reflects according
to Fresnel's law. The layer is characterized by the scattering indicatrix of its constituent
particles, the single scattering albedo, and the optical thickness. The noteworthy advantage ofthe model is taking into account the processes occurring in the volume.
The model is based on the solution of the radiative transfer equation by various numericalmethods: the method of discrete ordinates, a small-angle modification of the sphericalharmonics method. The model also enables finding a solution using the matrix -operator
method for a medium of several layers, each of which is chara cterized by its properties.
The described model is implemented in the Matlab programming language, and a fairly highcalculation speed is achieved. In the future, the model will be filled with the characteristics ofreal media.
When building analytical models, certain assumptions are always made. In numerical models,
many of these assumptions can be avoided. Besides, it is possible to take into accountadditional factors and herewith to get a deliberately more accurate result.
Therefore, the authors develop a numerical model in parallel with the analytical model. It isbased on the principle of representing the reflective surface as a scattering layer with adiffuse substrate and a randomly uneven Fresnel boundary on top.
An important requirement for the numerical model is to take into account the state of lightpolarization since it has a great influence on all processes that occur during the transfer ofradiation in the scattering medium. Therefore, instead of luminance, the numerical model uses
the Stokes vector, which is essentially a "vector luminance" and therefore organically suitable
for solving lighting problems. In this case, all the equations take a vector form. There alsocomes a need for a reference plane, which plays the role of a reference syste m. Its rotationmust be taken into account at each act of light scattering.
It worth to note that when modelling a randomly uneven Fresnel boundary, the presence of aslope correlation is taken into account, which always occurs because of natural exposure or
artificial treatment. This enables observing the phenomena that occur in reality in the model.
These include, for example, the effect of a statistical lens, a state of agitated water surface,135

CIE 2021 - Abstract Booklet

when it affects the passing rays like a real optical lens. Wi thin the framework of the model
under consideration, the authors managed to reproduce this effect.
The algorithm for modelling the radiation transfer in the scattering layer is based on the use of
the local estimations of the Monte Carlo method. This appro ach enables getting an estimatedluminance value at the point of interest, and also significantly reduces the calculation time.
3. Results
The first results of modelling the luminance factors of some surfaces gave a qualitative
coincidence with the results of other authors.
The obvious price for greater accuracy of calculations is the increasing calculation time, whichmakes the numerical model of little use for practical problems. However, it is of interest fromthe point of view of using some of its elements in the analytical model to improve the accuracyof the latter. First of all, a randomly uneven Fresnel surface is considered in this sense.
Also, in some special applications, especially where polarized light is considered, the use of anumerical model will be inevitable.
The created measuring system based on a goniometer, a luminance meter, a set of polarizing
filters and an illuminator with a parallel beam of rays enables measuring the components of
the Stokes vector (and, consequently, luminance) in different directions of observation andillumination. The first measurements showed a good agreement between the experiments andthe mathematical model.
4. Conclusions
Currently, the main efforts of the authors are aimed at measuring the luminance factors ofvarious real surfaces in the laboratory and comparing them with the curves obtained using
models. It is planned to refine the model and fill it with parameters as a result of
measurements. In the future, it will allow taking into account the state of th e road surface
when designing lighting.

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OP55
KEEPING THE BENEFIT OF ILMD’s HIGH RESOLUTION IN MEASURING LIGHTINGQUALITY PARAMETERS
1

Boucher, V.1, Bushmann, S.2, Greffier, F1., Muzet, V3, Voelker S.2
Cerema, UEL team, Angers, FRANCE, 2 TU, Berlin, GERMANY, 3 Cerema ENDSUM,
Strasbourg, FRANCE
vincent.boucher@cerema.fr

Abstract
1. Motivation, specific objective
The dimensioning of lighting installations is performed according to the specifications of CIE
documents and relevant standards. To calculate luminance-based quality criteria, a grid insidea ‘bird view’ of the relevant field seen by the observer has to be defined. These are usually
three transverse and a minimum of ten longitudinal points per traffic lane, i.e. typically 60
points for two lanes. This methodology is due to historical reasons: manual measurement witha punctual luminance meter which was both pragmatic and efficient when the calculation tools
were less advanced.
Nowadays in road lighting design, Imaging Luminance Measurement Devices (IL MD) are able
to produce experimental luminance maps with high resolution which can be much higher thanthe human eye‘s one. These on site measurement maps are often compared with calculations
obtained by common lighting calculation software.
Differences are often observed between simulations and experimental measurements
regarding the quality criteria and luminance distributions. Despite simulation andmeasurement uncertainties in general the discrepancies may be caused by three problems.
-First, it could be a lack of resolution of the actual photometry of the luminaires.

-

Second, it could be because of the comparative method. It is questionable why
experimental luminance maps which are nearly trapezoidal seen by the standard observer
are not used. Instead, they are compared using the CIE rectangular grid. Plus, it is actually
undefined how to perform the CIE grid projection in these high resolution images.

-

Third, discrepancies between measurements and simulations could be a problem ofignorance of the photometric characteristics of the road.

In this study we have focused specifically on the first two points.
2. Methods
To strengthen the results, the study was conducted using two lighting design software
packages developed by independent research institutes and tested on two existing
installations.
In the first stage, the impact of the luminaire's photometry was studied by considering two
scales of resolution in the reference frame for C and γ: the classical resolution stipulated instandards which is the interval of 5° for C values and 2.5° for γ va lues and a finer resolution
with an interval of 1° for C and for γ.
In order to match experimental results and calculations, two methodologies are generally
followed concerning the resolution and shape issue:11) downsample the image resolution in averaging areas (2’x20’) centred on the grid points.
Then in the results, the high resolution benefit is lost, and the details and heterogeneities
perceived by the observer's eye are no longer noticeable.

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12) the grid is reported in the ILMD image and measurements are tak en at these specificpoints. But the transformation of the measured polygon into a rectangle comparable to thestandard grid requires interpolations which can influence the quality criteria. Moreover,this method is very sensitive to the grid positioning (minimal values can vary drasticallyfrom one row of pixels to another) and can lead to high discrepancies.
In a second stage, the influence of the shape of the calculation area and its resolution were
tested using the classic lighting quality criteria defined in CIE140, which are averageluminance and overall and longitudinal uniformity. To do this, simulations were comparedusing a rectangular shape compliant to the CIE grid and a nearly trapezoidal shape that
corresponds to both the ILMDs' and the observers' vision. In the reference documents, aresolution of 2' in longitudinal x 20' in transverse is recommended without justification. We
preferred the use of 2’x2’ to match the human eye’s resolution. The influence of the resolution
was studied by considering several resolutions between the 60 standard points and a highresolution available with 1 cm / pixels.
3. Results
Concerning the impact of the luminaire, all our simulations showed that there were no
noticeable effects on the resolution of the luminaire . It should be noticed that our luminaires
do not present high peaks in their intensity. The characterizations carried out classically are
therefore sufficient.
Our proposed alternative approach is to keep a resolution identical to the human eye’s one (2’x 2’) in the luminance image and to compute the calculations with the same points density.
Then calculation results could lead to a trapezoidal grid directly comparable to theexperimental image. As in classical way, the average luminance could easily be c omputedwith this new methodology. For the overall uniformity, the minimal luminance value foundcorresponds to a real perceived value and not an average. The most difficult part is to definea methodology for the longitudinal uniformity to avoid its high sensitivity with respect topositioning. In our paper, we compare the classical methodologies with our alternative
calculation method with a constructed grid based on 2’ x 2’ elliptical areas which is the humaneye’s cones projection.
4. Conclusions
The use of the classical grid recommended by the CIE can lead to very different results
depending on the calculation method used. ILMDs offer new possibilities thanks to their highresolutions and our goal is to keep this benefit in quality criteria evaluation. We propose a
new methodology to match experimental measurements and calculations which allows us tobetter take into account the perception of users.
A validation of this approach will be carried out by comparing simulations with fieldmeasurements, also considering the impact of road photometry.

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Session OS16
D1 – Lighting trade-offs
Wednesday, September 29, 19:45–21:15

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OP56
DAMAGE REDUCTION WITH MAINTAINED COLOUR QUALITY OF ARTWORK UNDERRGB PROJECTOR
Kore, R.S., Durmus, D.
Pennsylvania State University, University Park, USA
rsk97@psu.edu

Abstract
1. Motivation
Light is needed to initiate vision, but visible radiation causes damage to artwork. When lightfalls on a surface, it is either reflected, transmitted (if surface is transparent or translucent) , orabsorbed. The absorbed light turns into heat and may damage pigments. In the display the art,
visual appearance and damage are inversely related (i.e. the ideal condition to prevent thedamage to artwork would be total darkness). Current conservation standards that are basedon Harrison damage curve, indicate that the energy in shorter wavelengths has more potential
to cause damage compared to energy in longer wavelengths. Historically, Harrison curve
caused an upsurge in the use of incandescent sources in museums. Although incandescentsources emit very limited energy in shorter wavelengths, they have low luminous efficacy andemit most of energy in longer wavelengths, which also damages to artwork by increasing
surface temperature. Since only the light that is absorbed by a pigment causes damage,damage to light-responsive materials (e.g. oil painting, silk, paper) can be reduced by
optimizing the light source spectrum to reflectance factor of the material. For example, a red
pigment reflects more light in longer wavelengths, while the energy absorbed in shortwavelengths may damage the pigment. The absorption minimization approach enables
optimizing the light source spectral power distribution (SPD) to prevent damage by reducing
absorbed light while maintaining the colour quality of artwork.
In addition to damage and colour quality of artwork, lighting also plays a key role in energy
consumption. Light emitting diodes (LEDs) provide higher efficacy, long lifetime, spectral andspatial tuning, and the ability to integrate with other semi-conductor devices, such as sensors
and control devices. The integration to sensors and controls can lead to adaptive lighting
systems to improve lighting application efficacy by emitting light where and when it isnecessary. In previous studies, researchers have used both narrowband LEDs and theoretical
spectra to reduce absorption resulted in energy savings up to 71% without causing
perceptible colour shifts.
While absorption minimization approach has great potential for art conservation and energy
efficiency, the computational time and effort required to build a smart lighting system can beimmense. It is possible to reduce the computational time and effort by grouping spectralreflectance functions and optimizing SPD of a light source for a group of similar “colours”.
Previous absorption reduction studies grouped surfaces according to their spectral reflectanceshapes, but they did not investigate the optimal SPDs for each group, nor they applied thisconcept to art conservation. Here, an RGB projector was used to generate spectra toilluminate colour samples without causing colour shifts or increasing damage. Spectralreflectances of colour samples were grouped in terms of spectral shape similarity. Three
conflicting parameters, damage from absorption, colour quality, and energy consumption,
were used to optimize SPD in an absorption minimization approach.
2. Methods
A computational algorithm was developed to generate test SPDs using the limits of the
projector software control (between 0 and 255 values for each channel). The spectral output
of each individual RGB channel of the projector was measured at full output (255) using acalibrated spectroradiometer. The CIE standard illuminant A scaled to match the total power
output of RGB projector, was used as the reference light source to compare absolute damage
caused by optical radiation. The spectral reflectance functions of Macbeth ColourChecker

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samples were used in the optimization process to represent pigments. The colo ur samples
were divided into four groups based on reflectance function shapes: peak (green hue),plateau (red and yellow hue), peak incline (blue hue), and plain (achromatic samples).
Spectral reflectance for each group were generated by averaging spectral reflectance of thecolour samples in respective groups. The colour (ΔE 00 ) and hue (ΔH* ab ) differences were
calculated using the CIE 1976 L*a*b* colour space and CIEDE2000 colour difference formula.
Light absorption (A) was calculated as the ratio of the light absorbed by the paint under a test
SPD to the light absorbed by the paint under a reference incandescent illuminant as a proxyof damage to artwork. Energy consumption was reported as the ratio of the total power
emitted from the test SPD to the total power emitted from the reference illuminant SPD.
3. Results
The optimized SPDs that do not have similar reflected light (±10%) to the reference illuminant
were filtered out to avoid luminance-dependent colour appearance phenomena, such as Hunteffect and Bezold-Brucke hue shift. When the data were analysed for ΔE 00 < 1 (approximately
a just-noticeable difference), the energy absorbed by pigments (damage to artwork) was
reduced by 52% for peak, 32% for plateau, 56% for peak -inclined and 73% for plain types,
with 51%, 50%, 62%, and 72% of saving in energy consumpt ion respectively, when comparedto the reference illuminant. When the colour quality constraint was relaxed to Δ E 00 < 10 (aperceptible but not large colour shift), there was an 26% increase in reduction of absorbed
radiation for peak, 7% for plateau and 3% for peak-incline types, and 25%, 4%, and 3%
increase in energy savings. For plain group, increasing colour tolerance did not provide
significant benefits in terms of absorption reduction and energy consumption. The results
support the previously established trade-off between colour quality and energy efficiency.
4. Conclusions
Light is needed to appreciate artwork, but optical radiation absorbed by surfaces can cause
irreversible damage. Absorption reduction approach can reduce damage to artwork withoutcausing perceptible colour shifts. However, the computational time and effort to optim ize lightsource spectrum for each pigment on a painting might be tremendous. Pigments can begrouped according to their spectral reflectance shapes to reduce computationa l time andeffort. The spectral optimization of an RGB projector for damage, colour quality, and energy
efficiency indicates that damage reduction can be reduced without causing colour shifts.
Increasing the colour shift tolerance can further reduce light absorption. Future studies will
investigate observers’ subjective evaluations of artwork under optim ized lighting conditions forheritage preservation.

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OP57
THE DIFFUSENESS OF ILLUMINATION SUITABLE FOR REPRODUCING OBJECTSURFACE APPEARANCE USING COMPUTER GRAPHICS
Mizushima, S.1, Kudo, H.2 Dobashi, Y.2 Mizokami, Y. 1
1
Chiba University, Chiba, JAPAN2
Hokkaido University, Hokkaido, JAPANsuzuki-mizushima1125@chiba-u.jp

Abstract
1. Motivation
With the evolution of solid-state lamps, including light-emitting diodes (LED) and organic lightemitting diode (OLED) lighting, lighting with various types of intensity, spectral power
distribution, and spatial distribution are available. The lighting condition changes dependingon the lighting form, and the change of the lighting condition affects the appearance of theobject. The diffuseness of lighting can affect the appearance of objects significantly. It is
important to define lighting conditions realizing accurate material appearance and ideal
material appearance. We previously showed that a lighting condition with moderate
diffuseness is better for an accurate material appearance using real objects and lighting.
Computer Graphics (CG) is a powerful tool for simulating various lighting environments. Still,it has not investigated if the influence of diffuseness on an object’s CG simulation appearance
is similar to the real one. This study aims to find the lighting condition exhibiting an accuratematerial appearance in a CG environment. We also examine the lighting condition for an ideal
material appearance. In the experiments, we tested the influence of diffuseness of lighting on
the appearance of objects with different materials to find the material dependency.
2. Methods
Observers memorized the appearance and tactile impression of objects by looking at preobservation CG images created with environmental maps. Then they observed test images
created under different diffusive lighting conditions and determined a suitable diffusenesslevel to reproduce the objects' surface appearance. Objects used for stimuli are plastic, roughplastic, and gold spheres. These materials are offered in Mitsuba's conductor model. The pre observation images were the simulation of each object under three types of environmental
maps, "Rainy Day," "At the Window (Wells, UK)," and "Overcast Day / Building Site (Metro
Vienna)" provided on the site of the Light probes. The diffuseness of the map was 0.65, 0.55,
and 0.71 (by the Cuttle’s calculation method), respectively. We prepared images of an object
viewed from 6 directions for each object and each map. We created test images for evaluation
simulating the experimental environment by arranging a point light source in the centre of awhite sphere with a diameter of 20 cm. An object for stimulus was placed on the bottom of thesphere. Diffuseness was controlled by changing the reflectance of the inner wall of the sphere.
The seven levels of diffuseness (0.19, 0.26, 0.39, 0.54, 0.66, 0.79, and 0.91) was produced.
The average luminance of each test image was set at 138 cd/m 2 . The observers memorized
objects by looking at pre-observation images beforehand. In the experiment, observers
compared the test image with their object’s memory. They selected the diffuseness condition
that the appearance of the object was closest to the memorized object and that ideally
represents the surface appearance of the object for each stimulus. Observers also evaluatedthe impression of stimuli under each viewing condition on ten items using a seven -point scale.
The items included the impression such as "weight," "visibility," "naturalness," and "gloss."
3. Results and discussion
In the accuracy evaluation, the moderate diffuseness was highly evaluated. The most highly
valued diffuseness for each stimulus is within the diffuseness range of the observation image
in which the observer memorized the appearance of the object. This trend is consistent with
our previous results of experiments conducted in the real environment. However, the results
were not as stable as those in the real environment, indicating that we need further

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investigation for the difference between a real and CG environment. We also need further
investigation to clarify whether the diffuseness level for accurate appearance is determined by
the environment in which the appearance was memorized or the natural range of diffusenessin the ordinal environment. The diffuseness condition that ideally represents the surface
appearance of the gold object showed a different tendency from other stimuli. Our results
suggest that it is possible to define a diffuseness level for accurate appearance common toobjects with different materials. In contrast, the diffuseness condition for ideal appearance
would have material dependence. The evaluation of ideal material appear ance had amoderate correlation with "naturalness" and “visibility". This suggests that lighting that makes
an object look natural and visible can ideally reproduce objects' surface appearance.
4. Conclusions
We investigated lighting conditions exhibiting an accurate material appearance and an ideal
material appearance by evaluating different lighting distributions in CG environments. It wassuggested the possibility to define a diffuseness level for accurate appearance common toobjects with different materials. However, the difference of material should be considered forthe diffuseness condition to realize the ideal appearance. The usefulness of the CG
experiment was suggested by the fact that our results showed the same tendency as theexperiment conducted in the real world.

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OP58
A STUDY ON THE DIFFERENCES IN VISION BETWEEN THE YOUNG AND THE
ELDERLY IN SIGNS
1

Ishihara, M.1, Suzuki, K.1, Heo, J.1
Shimane University, Matsuecity, JAPAN
piano-and-maha@ezweb.ne.jp

Abstract
1. Motivation, specific objective
In a society where the global population is aging, it is necessary to develop environments thattake into account the physical characteristics of the elderly. Among the many physicalchanges that accompany aging, the decline in the ability to see, the most important source of
information, is a major problem. Typical eye diseases in the elderly include age -related
cataracts, glaucoma, and age-related macular degeneration. Age-related cataracts make it
difficult to perceive colours correctly, glaucoma narrows the field of vision, and age-related
macular degeneration distorts or darkens the centre of the field of vision. Since the visualcharacteristics of the elderly are different from those of the young, universal design has been
adopted in many areas of architecture. However, in signage planning, design for physicalchanges due to aging and universal design have not yet been applied, but elements such as
the size, colour, and brightness of letters are being actively researched. Therefore, this study
was positioned as a basic research and focused on the difference in brightness and the sizeof the letters, taking into account the visual characteristics of the elderly. We conductedpsychological evaluations of young and elderly people in order to clarify differen ces in sign
visibility between them.
2. Methods
Nine different images were presented in sequence on a computer display, and the participants
were asked to rate their impressions of each image from two different viewing distances. An
evaluation sheet based on the SD method was used for evaluation. The rating scale consistsof 15 items with seven levels of evaluation. The variables are "font size," "brightness
difference between background colour and font colour," and "viewing distance. Character size
was set to three patterns: 9mm, 20mm, and 40mm. The luminance difference between the
background colour and the text colour was set to three patterns. Three patterns were set: (n2,n9.5) (n3, n9.5) (n4, n9.5). The "viewing distance" was set to two patterns: 2000mm and
3000mm. The presented image was a two-letter idiom, with a total of 18 strokes, and the font
type was set to MS Gothic. The subjects consisted of 20 young adults (10 males and 10
females) and 10 older adults (5 males and 5 females). The collected data were statisticallyanalysed by factor analysis and analysis of variance, and the results of impression evaluation
were calculated. The analysis of variance was based on the factors extracted in the factor
analysis.
3. Results
First, let's discuss the results of the impression evaluation. The results of the impression
evaluation were close to 4 overall, with the younger age group giving higher ratings than theolder age group in 12 items except for the three items of "likeability," "conspicuousness," and"dynamic. By age group, the younger group gave significantly higher ratings in the items of"calmness," "stability," and "coherence," and significantly lower ratings in the item of "dynamic.
The highest rating was 4.70 for the "calmness" item and 3.12 for th e "dynamic" item, adifference of 1.58. The elderly had smaller differences in each item than the young, with thehighest rating of 4.02 for the "likability" item and the lowest rating of 3.39 for the "ease ofviewing while walking" item, a difference of 0.63.
For each image pattern, the images with the largest character size (40mm), the largest
luminance difference (N2, N9.5), and the largest viewing distance (3000mm) received the144CIE 2021 - Abstract Booklet

highest ratings for both the younger and older age groups. On the other hand , for the younger
generation, the images with the smallest text size (9mm), the largest luminance difference (N2,
N9.5), and the largest viewing distance (3000mm) were the images with the lowest ratings.
For the elderly, the images with the smallest font s ize (9mm), medium luminance difference(N3, N9.5), and viewing distance of 3000mm were the images with the lowest ratings.
Next, we will discuss the statistical analysis. As a result of the factor analysis, the items of
the SD method were classified into "visibility factor" which affects the visibility of the sign and"harmony factor" which is related to the design of the sign. An analysis of variance was thenconducted with the two factors of "visibility" and "harmony" as dependent variables and "fontsize," "brightness difference," "viewing distance," and "age group" as independent variables.
As a result, regardless of age group, visibility and harmony were affected by font size andviewing distance. The difference in brightness had an effect only on visi bility. As acharacteristic of the elderly, when the size of the letters became smaller, the harmony of theelderly decreased significantly compared to the younger generation.
4. Conclusions
In this study, psychological evaluation was conducted on young an d elderly people in order toclarify the differences in seeing the signs. The results showed that the size of the letters had
a greater impact on the harmonicity of the elderly than the young. This is thought to be due toage-related deterioration in visual acuity and changes in colour perception. Since the current
study was limited to achromatic two-letter words, additional studies with more colours andinformation content are needed in the future.

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OP59
COLOUR FIDELITY AND ILLUMINANCE TRADE-OFF: TESTING LIGHTING VALUES
1

Veitch, J.A.1, Whitehead, L.A.2
National Research Council of Canada – Construction Research Centre, Ottawa, CANADA
2
University of British Columbia – Department of Physics and Astronomy, Vancouver,
CANADA
Jennifer.veitch@nrc-cnrc.gc.ca

Abstract
1. Motivation, specific objective
The focus on energy efficiency in the development of solid -state-lighting has fuelled rapid
increases in the luminous efficacy of light emitting diode (LED) products, suggesting that thebest technologies will prioritize lumens per watt (lm/W) over other performance criteria.
Increasing the colour fidelity of a light source generally reduces its luminous efficacy ofradiation because this requires more of the radiation to be at wavelengths th at are farther
from the V(λ) function peak. The visual system readily adapts over a wide range of photopic
illuminance levels, but cannot “adapt away” colour fidelity error; therefore, some havesuggested that there is an optimum range for colour fidelity that is significantly higher thanthat provided in most present-day LED products, in which case energy efficiency can be
maintained through a small, probably unnoticeable, illuminance reduction. This paper reports
two experiments aimed at testing the feasibility of this approach to energy efficiency.
2. Methods
Experiment 1 required participants to simultaneously view pairs of light boxes whose sources
differed in colour fidelity, at either a higher (346 lx) or lower (277 lx) illuminance. Eachparticipant saw a unique random order of 15 possible pairs, including null trials andcounterbalancing by presentation side. Colour fidelity differences between the two sides were0, 5, 9, 11, 16, or 25 R a units. For any given trial, both sides were at the same illumin ance,
and there was an adaptation period at the start of each trial before any judgements were
made. The dependent measures were performance on a timed reading task (presented at two
print sizes) and judgements of the colour appearance of the pair as a who le in terms of colour
consistency, adequacy of light level and overall satisfactory nature.
Experiment 2 also used simultaneous viewing, but removed differences in light source
chromaticity to focus on the colour appearance that an illuminant imparts to o bjects. This wasachieved by lighting the boxes with an incandescent lamp (R a = 100) but varying theappearance of objects placed on display to simulate the effects of chosen illuminants on
defined reflectance spectra. The objects were 5 paper cubes (red, orange, yellow, green, andblue) printed with calibrated colours to achieve the chosen effects. Illuminance was varied
using neutral density filters, giving two levels (277 lx and 346 lx). The only task was to judge
the appearance of the objects. In each pair there was one reference stimulus, and a second
stimulus that was one of the five sets: reference, high colour fidelity, average colour fidelity,
low colour fidelity, or very low colour fidelity. The reference side varied between the right andleft side. The order of presentation of pairs and illuminance levels (18 trials per participant)
was random.
3. Results
For Experiment 1, the reading performance scores (speed and errors) were analysed in a 2 x
2 (illuminance by print size) multivariate analysis of variance (MANOVA). There was a large
effect of print size on reading speed, but no effect of illuminance on reading performance.
Illuminance effects on colour judgements were also tested using MANOVA with illuminance as
the independent variable and three dependent variables: colour consistency, light level
adequacy, and overall satisfactory nature of the appearance. Illuminance in the range studied
did not measurably affect the judgements.

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Hierarchical linear modelling (HLM) was used to examine the effect s of the independent
variable (colour difference between the boxes) on the three colour judgements. These
analyses were repeated for the differences between the sides expressed with R a , D uv , and T c .
The most interpretable results were obtained for D uv and T c . The larger the difference between
the boxes, the lower the judgements of colour consistency, adequacy of light level, andoverall satisfactory nature of the lighting.
Experiment 2 was a 2 (illuminance) x 5 (colour fidelity) factorial repeated -measuresexperiment, with three dependent variables: colour consistency, adequacy of light level, andoverall satisfactory nature of the lighting, analysed using MANOVA. The high illuminancecondition resulted in higher ratings of the adequacy of the light level and the overallsatisfactory nature of the light, but illuminance did not affect the colour consistency
judgements nor did it interact with colour fidelity. The colour fidelity difference between thetwo sides predicted the colour judgements on all three ratings. The ratings were always
highest when both sides were the reference condition (for which R a = 100). The pair in which
the test case was the very lowest colour fidelity always had the worst ratings. Examining thecolour shifts for each cube revealed that the “low colour fidelity” condition had smaller colour
shifts for the red and green cubes than the “average colour fidelity” condition, and thisaffected the order of the intermediate conditions.
4. Conclusions
These experiments were designed to test the hypothesis that viewers are very sensitive tosmall differences in colour fidelity but less sensitive to changes in illuminance. The results
generally support this hypothesis, although further investigation will be required to refine
guidance.
Many jurisdictions limit the allowable electrical power density in buildings, and there are bothnormative standards and recommendations for the target illuminance ranges for activities invarious spaces. Given the adaptability of the visual system to variations in illuminance, there
is a critical question for the lighting designer: What is the best colour fidelity in this space,taking into account the aforementioned trade-off between illuminance and colour fidelity whenpower density is held constant? This is not an energy-use issue, but rather one of humanfactors optimization.. The results from this project reinforce the view that higher colour fidelity,(for example with R a [or preferably, the more accurate CIE/IES measure for colour fidelity, R f ]in the range 90 to 95) provides light of higher net value for participants than does lower colour
fidelity (for example with R a or R f in the range 80 to 85), despite the consequent slight
reduction in illuminance. Further experimental work is required to better evalua te this trade-off
in real working environments.

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Session OS17
D3 – Tools; Cultural concepts
Wednesday, September 29, 19:45–21:15

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OP60
VIRTUAL REALITY: A PROMISING APPROACH FOR LIGHTING RESEARCH
Bellia, L.*, Corbisiero, F.1, D’Agostino, P.1, Fragliasso, F.1* University of Naples Federico II, ITALY

Abstract
1. Motivation, specific objective
In recent years, the use of virtual reality as design tool has gained interest among experts
operating in building sectors, among which lighting designers. Undoubt fully, immersive virtualenvironments (IVEs) seem promising in different phases of the design course, offering a
support for the decision-making process, the communication with customers, and the
management of the construction site.
The potential of IVEs would seem even more promising for research applications. Often,lighting experimental research is based on the analysis of people’s answers to luminous
stimuli and of their interactions with the luminous environment. Studies on comfort conditions,preferences about lighting characteristics, colours perception are significant examples in thissense.
In these cases, the realism of the test spaces is crucial: the more realistic the luminous
conditions, the more acceptable the obtained answers. Consequently, t he best way to conduct
such a research would be to observe people’s behaviour in real spaces. However, that would
imply several practical difficulties, among which the impossibility to keep under control all theparameters affecting human perception. On the contrary, laboratory conditions, despite minor
realism, provide major control of the involved variables and the additional possibility to vary
them according to a systematic approach.
For all these reasons, researchers have experimented different method ologies to test people’s
preferences about light: use of simulated spaces visible on computer screens, scale models,
full-scale test-rooms reproducing real environments. This last approach guaranties the mostreliable results, providing experiences comparable with the real ones, but it is expensive interms of money and time.
In this sense, IVEs could represent a promising tool, not only to speed up the experimental
set-up, but also to provide a major versatility in modifying the environmental parameters(geometry of the space, characteristics of the sources, optical properties of the materials).
Indeed, the IVE can be built and changed at will, with lower costs in terms of money and effort.
Despite the mentioned benefits, according to available studies it is not completely clear how
much the virtual environments can be considered representative of the reality in terms ofluminous sensations perceived by people. The paper investigates this issue. It is part of awider research project divided in three parts. The first part consists in an analysis of thecurrent state of the-art and of the available tools to design IVEs. Based on the acquired
information, a specific modelling software (Unreal Engine) was chosen, and its potential wastested from two different points of view: the readability of the calculation engine to evaluate
photometric quantities; the realism of designed virtual spaces viewable by means of head mounted devices (HMD).
2. Methods
2.1 Analysis of the state of the art
This phase provided on one hand a review of the different methodological approaches appliedin studies involving virtual reality and, on the other hand, a comparative evaluation of theavailable modelling software underlining their limits and potentialities. Finally, Unreal Engine

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was chosen for the following research phases since it contains a module (the Pixel Inspectortool) allowing luminance values to be calculated. In this way the same virtual model can bevisualized by means of HDMs and used to perform calculations.
2.2 Analysis of the readability of the calculation engine
The analysis was conducted in three steps.
A simple virtual room was built. The light sources were modelled as isotropic or perfectly
diffusing and the way the software calculates the direct component of light w as
investigated, without considering the interactions between light and the environment. The
results obtained in terms of illuminance were compared with manual calculations.



The same model was built in DIVA for Rhinoceros. In this case, the light sources weremodelled by means of photometries imported as .ies files and considering Lambertiansurfaces. This step was fundamental to test how the software calculate the reflectedcomponent of light.

Finally, a more complex model representing a real test-room was built. It is a rectangularroom equipped with two white-tuning LED panels. Three perimetral walls are covered bywhite curtains. and one with three different curtains (white, black and grey) that can belowered in turn. Six different light scenes were defined (three curtain colours and two
CCTs -3000 K and 6000 K-). Spectral reflectance measurements were performed to obtainthe chromatic coordinates of the materials (from which the reflectance in the RGB
channels were derived) and the specular component of the reflection. The light sourceswere modelled by using photometry provided by the manufacturer. The results obtainedwith the two software were compared between them and with on -field measurements.

2.3 Perceptive analysis
The Unreal Engine virtual model was set to be visualized thanks to the use of a headmounted device (DELL VR-PLUS100) establishing two different levels of interaction: theformer in which the person wearing the HMD can simply see the 6 different light scenes in asequence administrated by the researcher; the latter where the person can change CCT ofsources and colours of the curtains at will. A questionnaire to test the sense of presence ofpeople regarding the virtual model was prepared. Unfortunately, this research phase wasinterrupted due to the Covid-19 pandemic.
3. Results
The comparison between software demonstrated a good readability of results of Unreal
Engine. The percentage differences between the two software are contained for both models,being on the average equal to 13% and maintaining themselves low even when the model ismore complex.
4. Conclusions
The use of virtual reality seems promising for lighting research purposes. The presented
results demonstrated the goodness of the analysed software in terms of calculation eng ine
characteristics. Moreover, the setting of the virtual model viewable by using HDM is thedemonstration of how much useful the use of VR can be, to obtain models easily modifiable
and to monitor people’s reactions to environmental changes. Results from the final researchsection will be crucial. The authors hope to present at least part of them, trusting in an
improvement of the pandemic situation.

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OP61
HOW BUILDING INFORMATION MODELLING CAN SUPPORT IN INCREASEDRECYCLING OF LUMINAIRES AND LIGHT SOURCES
Baradaran-Razaz, N.1, Merschbrock, C.M.1, Jägerbrand, A.K. 2, Nilsson Tengelin, M. 3
Department of Construction Engineering and Lighting Science, School of Engineering,
Jönköping University, P.O. Box 1026, SE-551 11 Jönköping, SWEDEN, 2 Department ofEnvironmental and Biosciences, Rydberg Laboratory of Applied Science (RLAS), School ofBusiness, Engineering and Science, Halmstad University, P.O. Box 823, SE -301 18 Halmstad,
SWEDEN, 3 Department of Measurement Science and Technology, RISE Research Inst itutesof Sweden, Borås, SWEDEN
1

Abstract
1. Motivation, specific objective
This paper has two main objectives: I) we seek to contribute to a better understanding of how
waste resulting from new installations and retrofitting of luminaires in buildings can be
reduced, recycled, and deposits in landfills can be prevented. Recently developed digital
information systems such as building information modelling in conjunction with databases
containing recycling information can provide an opportunity for improving the present situationand increase the recycling of luminaires and light sources. This has scarcely been studied,even though life-cycle assessments (LCA) can help in the work with building information
modelling (BIM), i.e., if substantial and updated data on recycling for different luminaires andlight sources are available. Consequently, the second objective of this study was therefore II)
to investigate how a technology like BIM can help increase the availability of data forsupporting the recycling of luminaires and light sources, with a special focus on LED lighting.
This paper is an early case study at the crossroads of BIM, luminaire design, and recycling.
The paper provides ideas for increasing recycling, recovering materials, and protecting theenvironment by investigating how data on recycling can be used in BIM.
2. Methods
We used two methods: literature review and a series of interviews with experts working hands
on with electrical and luminaire design in the building and manufacturing industry. This paper
sets out to answer some of the above questions by investigating what is known about the end of-life circle of lighting luminaries. This is done by conducting a review of the research in thearea. The literature search is conducted based on a si x-staged search process. The databaseused to construct the findings in this paper is Scopus, the largest database for scientificabstracts in the world. The search was limited to include only articles written in English which
may be viewed as a limitation of this work. Moreover, our search was limited to only include
journal articles and book chapters. The literature review part of this paper presents what has
been presented in the identified articles. The articles cover a range of different topics related
to the end-of-life of lighting. Topics addressed range from usage of light bulbs in landfills to
the chemical recycling of rare earth elements used in lighting. Moreover, the review identified
several different types of recycling for lighting. For underst anding the role that BIM technology
may play in this context we use a theoretical framework designed for exploring theconfiguration of the interorganizational relationships. Semi -structured interviews with experts
in the building and manufacturing industry was conducted.
3. Results
The results from the interviews indicate that BIM technology, in conjunction with classification
systems for the built environment (i.e. CoClass), could be utilized by manufacturers to makeenvironmental product data more readily available for building design teams. This data could
then aid decision making at the end of life of luminaires. By having detailed knowledge aboutmaterials and their potentially adverse environmental impacts appropriate recycling decisions
come within reach. Findings are that fusing digital systems to better communicate data

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relevant for the recycling of luminaires requires creating a good fit between the information
processing needs and capabilities of all companies involved.
4. Conclusions
This study showcases that next generation virtual modelling technology, such as BIM, yields
opportunities for further improving environmental decision making. Moreover, tighter
integration of the information exchange between luminaire manufacturers and design teams i san important step towards achieving the circular economy.

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OP62
VERAM, A SUBJECTIVE AND OBJECTIVE VISUAL ERGONOMICS RISK ASSESSMENTMETHOD – A DESCRIPTIVE PAPER OF THE OBJECTIVE RISKS
Hemphälä, H.a, Heiden, M.b, Glimne, S.c, Lindberg, P.b, Nylén, P.d
Division of Ergonomics and Aerosol Technology, Design Sciences, Lund University, Lund,
SWEDENb
Centre for Musculoskeletal Research, Department of Occupational and Public Health
Sciences, University of Gävle, Gävle, SWEDENc
Unit of Optometry, Department of Clinical Neuroscience, Karolinska Institutet,Stockholm,
SWEDENd
Swedish Work Environment Authority, Stockholm, SWEDENa

Abstract
Specific Objective
A visual ergonomics risk assessment method, VERAM, was used in 217 workplaces, by 48
trained assessors. VERAM consists of both of a subjective questionnaire and an objective risk
assessment. Many of the studied workplaces had glare from luminaires or daylight, as well as
insufficient illuminance or too high luminance ratio within the visual field. The purpose o f thisarticle is to describe the gathered data and frequency of some risk factors in the visualenvironment.
Methods
The trained evaluators assessed the risks in the visual environment. The overall risk
assessment was rated for risk for (green – no risk, yellow – risk, red – high risk): lack of/glarefrom daylight, light distribution, the amount of illuminance on work area, luminance ratio, risk
for glare from luminaires, and risk for flicker/temporal light modulation.
Results
The percentage of workplaces that did not have a satisfying amount of daylight was 13 %.
Satisfying view through windows was present in 93% of the workplaces. The overall risk forlack of or disturbing daylight was present in 53 % of the workplaces and assessed as a highrisk in 16 %. The illuminance recommendations were not fulfilled at 27 % of the assessed
workplaces. The overall risk for insufficient illuminance was assessed to be yellow or red at
49 % and red at 10 %. The overall risk for disturbing light distribution i.e. direct lighting only,
was yellow or red in 70 % of the workplaces with a high risk/red in 22 %.
The luminance ratios were assessed to be yellow (>1:5) or red (>1:20) at 60 % of theworkplaces, 19 % were red. Assessment of the risk for glare from luminaires showe d that
61 % of the workplaces had a risk or a high risk (yellow or red), and 21 % of the workplaces
had a high risk (red). The overall risk for any glare was assessed to be yellow or red at 66 %of the workplaces and red at 24 %.
Visually detectable flicker was present in about 3 % of the workplaces and temporal light
modulation, TLM, in 43 %. The overall risk for flicker and temporal light modulation wasassessed to be yellow or red at about 33 % or the workplaces and 7 % was assessed to be
red.
Conclusions
The objectively assessed risk for glare from luminaires was present in a majority of theworkplaces. This shows that the placement or configuration of the luminaires is often not
being taken into consideration when designing a workplace. The configurat ion or shape of aluminaire affects the light distribution and the risk for glare. LED panels are frequently

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installed recessed without indirect lighting, thereby the dark surroundings around luminaires,
causing glare.
Reflexes in the computer screen and on the work area show that the luminaires and/or
windows are not positioned in the correct way with regards to the work area. More than half of
the assessed computer workstations had a risk or high risk regarding the position of thescreen in relation to windows and luminaires. The direction of the light sources can cause
reflexes and about half of the workplaces had light in front of the work station or from behind.
If the luminaire is placed in front of the worker, it can cause reflexes in the work surfac e and if
the luminaire is placed behind the worker it can cause reflexes on the computer screen. If
there is both direct and indirect ambient lighting present, the reflexes can be somewhat
reduced. In a workplaces with both indirect and direct lighting, th e visual environment is often
the experienced as more positive since it looks brighter and causes less glare.
The number of workplaces that did not fulfil the recommended illuminance levels was fairly
high, almost 25 %. There is a correlation between the amount of illuminance and performanceas well as subjective strain. Studies show that if a worker can control the amount of light at
the workplace, the wellbeing increases. To have a correct illuminance level as well as anability to change or dim the amount of light at a workplace. contribute to the workers’
wellbeing Some individuals are light sensitive or photophobic and for these individuals it isfundamental that they can adjust the lighting in line with according their preference. In an
open plan office, this can be difficult to accomplish, and can therefore affect the workers’
performance level even more.
Flicker visually detectable from the luminaires was fortunately only found in few of theworkplaces since it is tiring, disturbing and can cause hea dache. Visual flicker should thus beattended to quickly. Temporal light modulation was present in almost half of the workplaces.
The overall risk for flicker and TLM is high at about a third of the workplaces. TLM can be oneof the factors behind subjective strain and headache.
VERAM is an effective alternative to gather subjective data from the individual combined withprofessional assessment of the risks in the visual environment in workplaces, to improve thevisual environment and thereby reduce strain and increase wellbeing and performance.

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OP63
THE CULTURAL BACKGROUND CONCEPT IN THE FIELD OF LIGHTING
Izmir Tunahan, G., Altamirano-Medina, H., Unwin, J.
Institute for Environmental Design and Engineering, University College London,
London, UNITED KINGDOM
gizem.izmir.tunahan.17@ucl.ac.uk,
h.altamirano-medina@ucl.ac.uk, jemima.unwin@ucl.ac.uk

Abstract
1. Motivation, specific objective
Generally, ‘’culture’’ refers to the customs, beliefs and behaviour of societies. In lighting
studies, culture represents the climatic and indoor conditions people have experienced during
the major part of their life. Consequently, people exposed to different cultu res might havedifferent expectations of the lighting environment. Knowing the lighting expectations due tocultural experiences have numerous advantages; it could help meet the occupants’ needs andpreferences, and provide occupant satisfaction, reducing unnecessary energy consumption in
the built environment.
Lighting research to date has tended to focus on the impact of cultural background on glare
discomfort perception rather than daylight perception and satisfaction. Also, researchers’
approaches to the cultural background concept vary. The cultural components aredefined differently, because the cultural background concept in the lighting environment has
not been comprehensively defined yet. This paper aims to summar ize a systematic review tocreate a conceptual framework of cultural background in the lit environment, which could help
understand the impact of cultural background on daylight perception and expectation.
2. Methods
A systematic review was conducted following the PRISMA which is a guidelin e for reporting insystematic reviews and meta-analyses. Scopus, Web of Science, and LEUKOS, weresearched for electronic records using the Boolean search terms. Following the assessment of
the full-text articles for eligibility based on the method outlined in PRISMA, 1189 publishedresearch articles were exported to Mendeley to remove the duplicates (n=28). Then, articles
whose title or abstract did not provide appropriate information or did not meet the selection
criteria were removed (n=1126); the inclusion criteria considered documents including at least
one aspect of (day)lighting perception, published in English and peer -reviewed journals
excluding conference proceedings and books, and published during any year from 1990 toNovember 2019. The remaining full-text articles (n=35) were assessed for eligibility, included
if the interventions assessed the association between cultural background and daylightperception including daylight adequacy and discomfort glare. In addition to the databasesearch, a manual search was also conducted, and these articles were then considered forinclusion in the systematic review according to the inclusion and exclusion criteria.
3. Results
Eight published articles were found to be appropriate based on the predefined criteria. All ofthem have addressed the impact of cultural background on daylight perception; however, theirdefinition of culture and applications varied. Therefore, the articles were divided into fourconcepts according to their study approach. These were (1) ethnicity and/or physiologicalproperties of individual eyes, (2) the residential area, (3) the previous luminance environmentand (4) socio-cultural background.
4. Conclusions
This review has confirmed that there are differences in how people perceive daylight
conditions due to their cultural background and presented the approaches that need to beconsidered for the assessment of daylight perception in the context of cultural background.

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Future research should further test the components together and separately to investigate
which component is more influential on daylight perception.

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Session OS18
D4 – Pedestrian-related issues
Wednesday, September 29, 19:45–21:15

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OP64
THE VISUAL CUES USED TO EVALUATE OTHER PEDESTRIANS; FACE, BODY, OR
SOMETHING ELSE?
Hamoodh, K., Fotios, S.
University of Sheffield, Sheffield, UNITED KINGDOM
steve.fotios@sheffield.ac.uk

Abstract
1. Motivation, specific objective
Imagine that you are walking alone and see another pedestrian ahead: what are the visualcues that tell you whether to approach or to avoid this person? After dark, one aim of
installing lighting in subsidiary road is to enhance your ability to make this evaluation.
Past road lighting research has tended to focus on Facial Identity Recognition (FIR),
assuming that identity recognition is the critical element. More recent research has focussed
instead on Facial Emotion Recognition (FER) because it is associated with approach -avoid
decisions of unfamiliar people. Both approaches assume the face to be the critical feature ofanother person but this assumption has yet to be confirmed.
2. Methods
Two experiments were conducted to explore the hierarchy of potential cues to safety
judgements. Test participants were required to evaluate a series of images, these being
manipulated to target certain features. In experiment 1 the features were gender (of theobserved person), number of people, walking direction (toward or away from the observer),light direction (observed person was either front lit or backlit (similar to Fi g 3.2 in CIE
136:2000), and visibility of the face and hands. Experiment 2 considered variations in thevisibility of the face and of the hands, with, for example, head coverings obscuring the eyes or
the mouth, and with hands hidden in pockets or behind t he back.
Test images were photographs of actors (male and female) embedded into nighttime urban
scenes. The images were displayed on a PC screen and evaluated by seated participants(exp 1) or projected onto a large screen and evaluated by participants wh ile walking on atreadmill (exp 2) and evaluated using two procedures, category rating and paired comparison.
In category rating trials each image was evaluated separately, in a random order, after being
displayed for 0.5 sec to simulate a typical visual fixation upon other pedestrians. Experiment 1
used a 5-point response scale ranging from 1 = very unsafe to 5 = very safe. For experiment 2
this was modified to a 6-point response scale (from 1 = extremely unsafe to 6 = extremelysafe) to avoid a middle response category, with a supplementary trial included to compare
responses with 5-point and 6-point responses scales. For paired comparisons, the images
were observed in all possible pairs of 16 images, giving a total of 120 trials, with the task
being to identify the safer of the two images. Null condition trials were included within bothprocedures and presentation orders were randomized.
The sample sizes were 32 (experiment 1) and 44 (experiment 2), with an equal balance ofmale and female observers in each sample.
3. Results
Null condition results from the category rating procedure did not suggest a significant ordereffect. Null condition data from the paired comparisons suggested a significant position bias,
but this did not persist in between-conditions trials, assumed to be due to randomization.
Evaluations of different test images were suggested to be significantly different. The results ofexperiment 1 suggest that a person would feel less safe when the approaching person is male(rather than female), when there is more than one person, when they are walking towards

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CIE 2021 - Abstract Booklet(rather than away), when they are backlit (rather than front lit), and when the face and hands
are partially concealed.
The results of experiment 2 suggest that the feeling of safety dec reases as the face becomes
more covered, but did not suggest a difference for covering either the lower or upper part of
the face. Hand position had little effect on evaluations of safety unless they were placed
behind the body rather than placed in front, at the sides or in the pockets.
Taken together, these results suggest that visibility of the face is important: if this visibility is
reduced by clothing (e.g. a hood, sunglasses or a scarf) or lighting (back -lit rather than frontlit) then the feeling of safety is reduced.
4. Conclusions
The results of these experiments suggest that the face is an important cue for interpersonal
judgements, and thus supports a focus on the face in previous FIR and FER studies. A third
experiment is underway to validate these findings; this uses eye tracking to record gazebehaviour toward different elements of a scene, and will follow the area -weighted approach toanalysis of Fletcher-Watson et al, 2008.

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OP65
USING RELATIVE VISUAL PERFORMANCE TO PREDICT THE ABILITY TO MAKE
INTERPERSONAL EVALUATIONS
Fotios, S., Mao, Y., Hamoodh, K., Cheal, C.
University of Sheffield, Sheffield, UNITED KINGDOM
steve.fotios@sheffield.ac.uk

Abstract
1. Motivation, specific objective
Enhancing the ability to conduct interpersonal evaluations after dark is one of the reasons for
installing road lighting in subsidiary roads. Experimental research exploring the effect ofchanges in lighting on interpersonal evaluations has tended to follow one of two approaches;
Facial Identity Recognition (FIR) or Facial Emotion Recognition (FER). FIR was the task
originally employed, primarily to explore whether or not changes in spectral power distribution(SPD) of lighting mattered, with mixed results as to whether it did or did not cause asignificant effect. It was subsequently suggested that FER, the ability to discriminate between
facial expressions, would be a more representative task: it is not influenced by familiarity withthe target and is more relevant for evaluation of intent. Several studies have t herefore
investigated the effect of changes in SPD on FER, and these do not suggest that SPD has
significant effect. However, while data from these studies have been considered in discussionof guidance for pedestrian lighting they have yet to deliver a co nclusion regarding optimal
lighting.
Rather than further experimental work, we instead considered a different approach tointerpretation of optimal lighting for interpersonal evaluations: prediction using Rea andOuellette’s Relative Visual Performance (RVP), a model of on-axis visual performance whichuses details of the task, the observer and the luminous environment to predict performance.
Using RVP does not require consideration of how the task is operationalized - whether FIR or
FER.
2. Methods
The independent variables used in RVP are observer age, adaptation luminance, target size
and the luminances of the target and its background.
Age is important because visual function declines throughout adulthood, tending to remain
stable up to the age of around 50–60 years and then undergoing a rapid decline. For thisanalysis, observer ages of 25 and 65 were used.
Following CIE TN 007:2017, adaptation luminance was estimated as the road surface
luminance. For subsidiary roads, illuminance is the measure of l ight level, with the P-classes
in CIE:115 2010 recommending six steps of illuminance from 2.0 lx to 15 lx. The basis ofthese illuminances is uncertain so it would be worth considering the benefit of higher
illuminances. The determination of road surface luminance for a given illuminance requires
knowledge of the reflectance which was assumed to be a diffuse reflectance of 0.2
Luminances of the target and its background are used in RVP only to calculate contrast. For
the current analysis we instead used facial contrast. Facial contrast is the contrast of the lips,
eyebrows and eyes against the skin immediately surrounding these features. Facial contrast
varies with skin tone and hence we used Caucasian and South African faces, whichcorrespond approximately to types II and VI of the Fitzpatrick Scale. The global facial
contrasts of these faces were estimated to be 0.314 (Caucasian face) and 0.138 (South
African face).
Visual performance is affected by task size, with an increase in task performance as task s ize
increases. For the current analysis task size was characterized using the area of the inner160

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features of the face which contains the eyes, eyebrows and mouth. The solid angle subtended
by the face varies with the distance at which it is observed. In thi s analysis we considered
three distances, 4 m, 10 m and 15 m.
3. Results
A typical situation in past studies is observation by a young observer of a Caucasian face:
RVP ranges from about 0.86 at 2 lx to about 0.93 at 15 lx, a steady but slight increase. The
effect of changing observation distance is negligible. If that same young observer now views aSouth African face, then RVP is reduced at all illuminances, ranging from about 0.7 at 2 lx to0.88 at 15 lux. RVP for observation by a young person of a South African face at 10 m
requires approximately 15 lx to match RVP for observation of a Caucasian face at the same
distance but at an illuminance of 2 lx.
Consider next an elderly observer. For this person RVP is greatly reduced compared to that of
the young observer. RVP for the elderly person observing the Caucasian face matches
approximately that for the young person observing the South African face. In other words, theimpairments to RVP of age (25 vs 65 years) and skin tone (Caucasian vs South African) a renear identical. As would then be expected, the greatest reduction in RVP is found withobservation of a South African face by an elderly observer, and for this situation the effect ofobservation distance becomes more significant.
4. Conclusions
These results show, as expected, that observer age and the skin tone of the observed person
both affect predictions of RVP for evaluation of the face. An inclusive approach to design
would suggest basing recommendations on an elderly observer and a South African skin tone
(which require higher adaption illuminances than do young observers and Caucasian faces):for this situation, the RVP vs illuminance graph suggests an optimal illuminance of around 7.5
to 10 lx. While higher illuminances steadily increase RVP, th is increase is smaller than the
reduction in RVP for illuminances less than 7.5 lx.

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OP52
ILLUMINANCE AT THE EYE AS A SIMPLE METRIC FOR DISCOMFORT GLARE FROMPEDESTRIAN SCALE LUMINAIRES
1

Abboushi, B.1, Miller, N.1, Fotios, S.2
Pacific Northwest National Laboratory, Portland, USA, 2 The University of Sheffield,
Sheffield, UNITED KINGDOM
Belal.abboushi@pnnl.gov

Abstract
1. Motivation, specific objective
Several discomfort glare metrics were developed for electric lighting, nevertheless the ability
to predict discomfort glare from pedestrian-scale lighting in nighttime environments continues
to be a challenge. This issue may be due in part to the limited number of studies on this topic
as well as differences among studies in experimental settings, measurements and procedures,and light source intensity ranges. While source luminance is widely used in discomfort glare
metrics, it can be difficult to consistently measure the luminance of small LED sources using acommon spot luminance meter. To resolve some of these issues, previous studies explored
metrics based on illuminance measurements at the eye such as direct illuminance fromsource (E direct ), indirect illuminance from source, and ambient illuminance.
In outdoor nighttime environments like sidewalks and parks, the contribution of indirect
illuminance is minimal due to low surface reflectance. This raises the question whether ametric solely based on E direct is appropriate, and how well it compares to metrics thatincorporate other quantities such as indirect illuminance from source, ambient illuminance,and source luminance. If feasible, a metric based on E direct can be measured using an
illuminance meter outfitted with a baffle, which can simplify field measurements of discomfort
glare. To address this question, the current study is a meta-analysis that used three
independent datasets from published peer-reviewed articles to evaluate the performance of
three metrics.
 E direct.
 The Bullough et al. 2008 metric (Bul08), which in addition to E direct , also considers indirect
illuminance from source and ambient illuminance.
 The Bullough et al. 2011 metric (Bul11), which in addition to E direct , indirect illuminancefrom source, and ambient illuminance at the eye (considered in Bul08), also incorporates
source luminance.
2. Methods
Existing discomfort glare studies from electric lighting were reviewed and their eligibility forinclusion in the current meta-analysis was assessed according to four criteria. Studies were
included in the analysis if they 1) were published in a peer-reviewed journal; 2) addresseddiscomfort glare from one light source under low background luminance; 3) measured
illuminance at the eye; and 4) utilized a randomized presentation order for experimental
conditions. Data from three studies were included in the current analysis. The number ofhuman subject discomfort glare ratings from these three studies were 216, 1692, and 1056,
respectively. In the current study, these datasets were analysed and performance of E direct,
Bul08, and Bul11 was ranked using several diagnostic tests including logistic regression,spearman correlation, true positive rate (TPR) and true negative rate (TNR), area under the
curve (AUC), and squared distance (SqD).
3. Results
The three studies examined a wide range of lighting conditions, as represented by E direct ,ranging from 0.2 to 82 lx and source luminance from 2000-750000 cd/m 2 . Discomfort glare

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ratings were either natively conducted or converted to a 9 -point De Boer scale (1= unbearable,
and 9= just noticeable glare). For logistic regression and receiver operating characteristic(ROC) curve analysis, 9-point ratings were converted to binary ratings such that ratings lessthan 5 were considered disturbing glare, and ratings larger or equal to 5 were considered non disturbing. Analyses were conducted using the ROCR package in R.
Overall, results showed that the E direct metric performed similar to Bul08 and Bul11 metrics.
Means of TPR and TNR were 0.71, 0.73, and 0.72 for E direct, Bul08, and Bul11, respectively.
Likewise, AUC and SqD across the three metrics were also similar and within 0.01. All three
metrics were significantly associated with the binary disturbing – non-disturbing ratingclassifications (logistic regression p<0.01) and were significantly correlated with discomfort
glare ratings (Spearman p<0.01). The borderline cut-off metric values between disturbing –non-disturbing discomfort glare were 10.2, 3.3, and 3.2 lx for E direct , Bul08, and Bul11,
respectively.
4. Conclusions
This analysis suggests that a simple metric solely based on E direct performed similar to Bul08
and Bul11. A cut-off value of about 10 lx was found to distinguish between disturbing and nondisturbing glare. The simplicity of this metric can prove useful to researchers and lighting
designers alike. We did not find substantial improvements for the two metrics ( Bul08 and
Bul11) that incorporated other terms such as indirect illuminance, ambient illuminance, andsource luminance. However, further analyses of other datasets might identify lighting
conditions where Bul08 and Bul11 metrics outperform E direct .

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WORKSHOP
PRESENTATIONS

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ORAL PRESENTATIONSIN WORKSHOPS
These abstracts were originally submitted for review by the International Scientific Committee
and have been accepted for presentation at CIE 2021. Additional unreviewed workshop
presentations will be given and are not presented in the Abstract Booklet.

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Workshop WS2
Adaptive road lighting
Monday, September 27, 17:30-19:00

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WP01
A HOLISTIC METHOD FOR THE COMMISSIONING AND OPTIMIZATION OF ADAPTIVEROAD LIGHTING SYSTEMS USING LABORATORY AND FIELD MEASUREMENTS
1

Bouroussis, C.A.1, Gašparovský, D.2
Lighting Laboratory, National Technical University of Athens, GREECE, 2 Slovak Universityof Technology in Bratislava, SLOVAKIA
costisb@mail.ntua.gr

Abstract
1. Motivation, specific objective
Road lighting technology has evolved dramatically in the recent years after it remained almost
the same for many decades. LED technology gave a boost to the luminaire design byincreasing the energy efficiency, by offering a great flexibility in lens design and technology
and by using efficient drivers. This led to a significant reduction of energy consumption inroad lighting. The introduction of intelligent control systems combined with luminaire specificcontrollers, introduced the concept of the Adaptive Road Lighting (ADL). This was also
motivated by the current lighting documents (e.g., CIE 115 and CEN/TR 13021 -1) which haveintroduced the concept of multiple lighting classes for the same road under differe nt
operational conditions. Today, the majority of new road lighting systems are equipped withadaptive control systems capable of achieving multiple lighting classes in course of the night.
For ADL systems, the lighting studies focus mainly on the higher o f lighting classes targeted
for the particular road. During installation of road lighting systems, the lighting control isusually programmed or set up using manufacture specific data in order to follow the desired
lighting classes. However, the experience showed that, in practice, the actual illuminationlevels vary due to tolerances and imperfections of the installation (position and orientation of
luminaires in application), deviations in the product-related data (luminous intensity
distribution), operational conditions (ambient temperature), conditions of road surface etc. In
addition, operation of the lighting control system can result to over -illumination or underillumination of road sections under various desired lighting classes or set points. In so mecases, the response of the system may be insufficient, unknown or unpredictable. There isalso a general concern on the operation of ADL systems from the perspective of the decision
makers regarding potential legal issues in case that the system do not deliver the desired
illumination levels and on-time.
The objective of this study is, therefore, the development of a standardized scheme for thecommissioning and optimization of the operation of ADL systems using field measurements
and by taking into account all aspects that may affect its performance. This work was also
motivated by the ongoing work of the CIE committee, the TC 4 -62 “Adaptive Road Lighting”
which is dedicated to this topic. The outcomes of this study can potentially be valuable for thework of this committee.
2. Methods
In this study, we performed a set of laboratory and field lighting measurements in several
sections of motorways of the national road network. This study deals only with M class roads
thus the measured quantity was the road luminance. The selected locations represented someof the typical geometries of the motorways, i. e., distance and height of poles, number oflanes, type of luminaires and so on. Therefore, each location and typical geometry
represented a large number of road sections having the same characteristics. The measured
results were compared to the corresponding lighting studies, considering the age of theequipment, the maintenance factor of the overall installation and other factors. In addition,
repeated measurements on specific locations were performed under different dimming
scenarios, ranging from 100% down to the lowest possible level of the luminaire’s luminous
output. The latter was used for the creation of the dimming curve and the time response of thecontrol system at the corresponding measurement location.

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Using the comparison of the measurement results, the lighting studies and the actual dimming
response of the luminaires, a master action plan was produced for each section. The plancomprises the fine tuning of the luminous output of the groups of luminaires in order to reachthe desired luminance levels according to the given lighting class, the correction of potential
issues in the operation of the control system, the update of the set points (dimm ing signals)
where needed, and proposed actions for cases where the luminance levels were not adequate.
In addition, the action plan taken into account the maintenance level of the installation inorder to schedule further field measurements after a major maintenance and the update of theaction plan.
3. Results
Measurement results showed that the actual achieved lighting levels on the road may
significantly vary compared to the ones from lighting studies. This is in most cases expected
due to the non-perfection of the lighting installation and the ideal calculation methods
established by relevant standards. The main sources of these disparities found to be mainly
the condition of the asphalt, the small or bigger deviations on the geometry of the measured
grids compared to the studies, the production tolerances of the luminaires and in some cases
the low quality of the luminaires which led to misleading calculation results.
The action that was applied in the tested motorways was developed having in mind its g eneralapplication as a commissioning method. Therefore, a generic holistic approach wasdeveloped and proposed for the commissioning of adaptive road lighting installations using
the field measurements, comparisons, masterplan building and action plan pre paration for
optimization and maintenance.
The paper will present the proposed workflow of actions and the holistic approach that can beapplied to all kind of roads equipped with adaptive road light systems independently of thelighting class (M, C, P, etc.).
4. Conclusions
This study revealed, in a quantitative and qualitative way, the most common issues anddisparities that can be found in real road lighting installations. The proposed method ofcommissioning via measurements, comparisons and action pla n can significantly reduce overillumination situation, to reveal potential issues that need further actions and to contribute to
the maintenance scheduling. This generic action plan can be developed per case taking into
account specific characteristics of the lighting systems or special requirements of the end
user and can be effectively included in the overall maintenance plan of a motorway or amunicipality ensuring the optimized operation of the lighting system and a maintained level ofroad safety.

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WP02
ASSESSMENT OF ROAD LIGHTING PERFORMANCE FOR TRAFFIC INTENSITY AND
TRAFFIC DETECTION BASED LIGHTING ADAPTATION
Gasparovsky, D., Janiga, P.
Slovak University of Technology in Bratislava, SLOVAKIA
dionyz.gasparovsky@stuba.sk

Abstract
1. Motivation, specific objective
Energy performance of road lighting can be described by various parameters such as simple
wattage or energy density, luminous efficacy of the installation, installation lighting factor,
utilance or, the most preferably, by the pair of compound numerical indicators PDI and AECI
established in the European norm EN 13201-5, also used in many non-European countries
worldwide. PDI stands for Power Density Indicator and AECI is acronym for Annual Energy
Consumption Indicator. The two indicators are related to different aspects of the system andcannot be combined to avoid mutual compensation. PDI is a measure of the performance oflighting installation itself, expressing efficacy of the used components and quality of thelighting design. AECI, on the other side, is indicating how efficiently the lighting is used for the
purpose and comprises factors based on light dimming and regulation, adapting to the actual
needs etc., i. e. the operation related aspects. Optimization of road lighting has many benefi ts
and goes far beyond energy savings, just to mention obtrusive light mitigation as one of the
key driving force of adaptive lighting. This paper is focusing on the AECI indicator and its
reduction potentials by application of traffic intensity detection as well as detection of lonevehicles. Aim of the paper is to derive typical values of the lighting operation factor for aseries of assumptions which can be assigned to common situations in road lighting, and to
estimate the savings potential due to traffic detection.
2. Methods
Daily course of operational profile of road lighting can be divided to several discrete lightlevels corresponding to particular lighting classes depending on and taking into accountcriteria set in the CIE 115. Road traffic intensity monitored over a suitable time span is
influencing selection of lighting classes which can vary throughout the night. In quiet periods
with lower traffic intensity the lighting can be dimed down and in late night hours it can beeven reduced to a lowest maintained level if no traffic is detected. Here the role of detectors
is to switch between consecutive (or other) light levels if a user appears in the area of interest.
To predict this behaviour in order to estimate the potential of light savings it is necessary to
account for some detection probability. This can be derived from normalized traffic data fortypical road categories acquired from long-term monitoring of traffic. The study is dealing withresidential areas (M5, M6), neighbourhood settlements and mid-class roads (M3, M4). For
detection of lone vehicles further assumptions are specified to estimate the duration of locallyincreased illumination. The operation coefficient c op is evaluated as result of the study, toillustrate the potential of savings.
3. Results
Results showed considerable potential of light savings (electricity consumption and light
pollution). Compared to full-level operational profile, application of quadruple level profile bymeans of traffic detectors can lead to as high as 50 % savings and even more on mid-classroads. In quiet residential quarters the reduction is yet significantly higher, preliminary results
showing savings of more than 60 % for entire quarters. However, for residential areas andneighbouring settlements harvesting and analysis of more data is needed to enhanceaccuracy of average probabilities and their dispersion.

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4. Conclusions
Considerable savings of light can be acquired by proper adaptation of light levels andsimultaneously by introduction of the sustained minimum light level to be applied when no
traffic user is detected in the area of interest, in order to provide additional functions. Thus,lighting adapting to actual traffic intensity and traffic detection should be promoted as a
powerful tool to save electricity and to mitigate adverse effects of obtrusive light.

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Workshop WS7
Revision of ISO/CIE 19476 and
CIE S 025
Tuesday, September 28, 15:45-17:15

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WP03
GENERAL V() MISMATCH INDEXHISTORY, CURRENT STATE, NEW IDEAS
Krüger, U.1, Ferrero, A.2, Thorseth A.3, Mantela, V.4, Sperling, A.5
TechnoTeam Bildverarbeitung GmbH, Ilmenau, GERMANY, 2 Instituto de Óptica, Consejo
Superior de Investigaciones Científicas, Madrid, SPAIN, 3 Technical University of Denmark,Roskilde, DENMARK, 4 Metrology Research Institute, Aalto University, FINLAND,
5
Physikalisch-Technische Bundesanstalt, National Metrology Institut of Germany,
Braunschweig, GERMANY
udo.krueger@technoteam.de
1

Abstract
The general V(λ) mismatch index, f 1 ’, quantifies the mismatch between the spectral
responsivity of a photometer, s(λ), and the spectral luminous efficiency function, V(λ). A shortreview of the history development will be given to explain why the current definition waschosen in the past and what adjustments may be useful for the future. The properties of thecurrent definition (e.g. its relation with the mean spectral mismatch error under specificpreconditions) is described in detail.
It is very likely that the calibration of photometers in the future will not only be done with CIE
Standard Illuminant A according to its spectral distribution S A (λ), but additionally with an LED
based CIE Illuminant L with its distribution S L (λ). The question therefore arises as to which
normalization should be used in future for calculating the normalized spectral responsivity of aphotometer for comparison with the V(λ) function.
With the literature review some aspects for the characterization of the general V(λ) mismatch
will be discussed in detail. Furthermore, the question should be investigated whether a single
characteristic value is sufficient to describe the spectral adaptation of a photometer in today's
world, since not only the measurement of white light of different colour temperature is ameasurement task, but the measurement of coloured light from LEDs is also becoming
increasingly important.
Motivation, specific objective
The general V(λ) mismatch index, f 1 ’, quantifies the mismatch between the spectral
responsivity of a photometer, s(λ), and the spectral luminous efficiency function, V(λ). It was
defined for the first time by the CIE in CIE 53:1982 for a general description of thephotometric performance of photometers, and it is used for selecting photometers requiring
minimal corrections under different illuminants in photometric measurements.
In daily measurement practice, almost only LED-based light sources are evaluated. Therefore,
in the near future, the calibration of photometers will be changed from CIE Standard
Illuminant A S A (λ) to CIE Illuminant L S L (λ), which should be taken into account in thedefinition of the mismatch index f 1 ’, if necessary. Furthermore, coloured light sources are
increasingly to be evaluated, whereby the current characteristic value unfortunately does no t
allow any prediction at all for the expected range of spectral mismatch errors.
History
The very first notation of f 1 ’ as informative note can be found in CIE 53:1982. The preferredmeasure at this time was the maximum spectral mismatch correction factor for 5 defined lightsources f 1,CIE . Later (CIE69:1987, 1987) the general mismatch index f 1 ’ was introduced more
officially.
In preparation for these first CIE publications, numerous publications (e.g. (Geutler,
Krochmann, Özver, & Röhricht, 1975), (Krochmann & Reissmann, 1980), (Krystek & Erb, 1980)and summarizing all (Krochmann & Rattunde, 1980)) were published, especially in the172CIE 2021 - Abstract Booklet

German-speaking world, which systematically showed that the chosen mismatch index, in its
form used today, made sense under the boundary conditions at that time and had advantages
over other candidates under discussion.
Current StateThe current (more or less unchanged) definition can be found in ISO/CIE 19476:2014 andsome applications of f 1 ’ for the estimation of the spectral mismatch correction factor forphosphor based LEDs and RGB type white LEDs can be found in CIE S 025/E:2015. Here agood correlation between f 1 ’ and the minimum and maximum spectral mismatch correction
factors of phosphor based white LED’s was found. The minimum and maximum spectral
mismatch factors for white light mixed from RGB LEDs however cannot be convincingly
estimated based on the f 1 ’.Therefore, he spectral mismatch error of coloured LEDs is notevaluable based on f 1 ’. This means a new or modified approach for the current lighting
situations is needed.
New Ideas from literature(Czibula & Makai, 1998) showed that f 1 ’ is not sufficient to describe or even predict the
spectral mismatch correction for LEDs and here especially for coloured LEDs. The autho rs
introduced two additional measurements using auxiliary detectors to estimate the spectral
mismatch correction factor very precise. Later on, in 2021, Young, Jones, & Muray introduced
a new quality metric f LED as the average absolute spectral mismatch error over a wavelength
region relative to the central wavelength of that region. Here the influence of bandwidth(change of bandwidth) and central wavelength (change of central wavelength) for the spectral
mismatch correction factor is discussed. The result is not a single value but a characteristic
field or matrix. One step further, in 2004, Csuti, Kranicz, & Schanda introduced a partial index
f’1,PART calculating a kind of f 1 ’ for specific wavelength regions (blue, green, yellow, red) basedon a calibration/normalization with a coloured LED in that region.
A new approach for the definition of spectral mismatch index f 1 ’’ was introduced by Ferrero,
Velázquez, Pons, & Campos in 2018, which provides a better correlation to the averageabsolute spectral mismatch error than f 1 ’, when this error is evaluated for phosphor-based
LED sources.
Conclusion
New requirements for the spectral characterization of photometers will be addressed andsummarized. Based on own calculations, numerous proposals from literature and new ideas,
the authors will try to define a new (or modified) characteristic value for f 1 ’ or several new
characteristic values which allow more flexible estimations of the mean spectral correction
error when using photometers under different todays bounda ry conditions.

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WP04
NOVEL EVALUATION METHOD FOR GENERAL PHOTOMETER MISMATCH INDEX F1’
1

Mantela, V.1, Askola, J.1, Kärhä, P.1, Ikonen, E.1,2
Metrology Research Institute, Aalto University, FINLAND, 2 VTT MIKES, VTT TechnicalResearch Centre of Finland Ltd, FINLAND

Abstract
In photometry, the spectral response distribution of the CIE Standard Observer is given by V(λ)
function. Photometer mismatch index f 1 ’ describes how much the spectral responsivity of aphotometer differs from the V(λ) curve. Previously, calibration of photometers has been
carried out with incandescent lamps. Thus, CIE Standard Illuminant A has been used as thereference spectrum in calculations. When the incandescent light sources are phased out, an
LED-based spectrum, such as L41 would be more suitable as the reference spectrum whenmeasuring LED sources. Defining an alternative spectral mismatch index would be useful. In
this study, we compare different methods to evaluate different proposed indices with different
reference spectra and propose a novel approach for evaluation of general photometermismatch indices.
1. Motivation
Photometers are often calibrated with light sources that differ in spectrum from the lightsource being measured, which results in measurement errors due to devi ation of thephotometer spectral responsivity from the defined V(λ) function. Spectral mismatch correction
factor (SMCF) is often used to correct this error. SMCF considers the different spectra andconverts the calibration result to the measurement carried out. Unlike f 1 ’, SMCF does nothave a unique value for a photometer. It is a set of values for different spectral distributions of
the used illumination.
Averaged SMCF can be compared with f 1 ’, calculated either with Standard Illuminant A or L41.
To get the orders of magnitude comparable, it is advantageous to take a n average of theabsolute value of SMCF-1. When calculating Pearson correlation coefficients of the SMCF
and f 1 ’ values, we can see how linearly their covariances correlate. As the standard deviationof the SMCF values tend to be smaller for smaller f 1 ’ values, the correlation coefficients might
be better than when using the mean value of SMCF-1.
2. Methods
We compared three different methods to characterize the SMCF values and compared thosevalues with the f 1 ’ values. Calculations were carried out for a set of 106 spectral responsivities
for different photometers and for 1299 spectral distributions of white LED -sources. For
Method 1, we calculated the mean of the absolute values of SMCF -1. In Method 2, we
calculated the absolute value of the mean of SMCF-1. Method 3 considered the standard
deviation of SMCF-1. As reference spectra for the SMCF values, we used two different
reference spectra, Standard Illuminant A and the newly developed LED spectrum L41.
The values obtained were compared with f 1 ’ values, modified f1’ values calculated byreplacing Illuminant A with reference spectrum L41, and with a novel approach for spectral
mismatch index f 1 ’’proposed by Ferrero et al (Optics Express, 2018). The “goodness” of thesemethods was evaluated by comparing the correlation coefficients between the SMCF methods
and the spectral mismatch indices.
3. Results
For Method 1, we got correlations of 0.7639, 0.7615, 0.6895 for SMCF A ; and 0.8782, 0.8904,
0.9882 for SMCF L41 as compared to f 1 ’, modified f 1 ’ and f 1 ’’, respectively. For Method 2, thecorresponding values for SMCF A were 0.5795, 0.5724, 0.5176 and for SMCF L41 they were174

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0.7567, 0.7615, 0.9344. Finally, for Method 3 using the standard deviation, SMCF A produced
correlations of 0.9255, 0.9352, 0.9705, and SMCF L41 resulted in 0.9278, 0.9371, 0.9709.
As the lamp data are for LED sources only, the first two methods clearly have worse
correlation when using Illuminant A as the reference spectrum. With SMCF L41 the correlations
are better with every candidate. However, when using standard deviation in Method 3, thecorrelations are good irrespective of the reference spectrum used. The correlations are betterin the Method 3 with both f 1 ’ variations compared to the Methods 1 and 2. The correlation of
f 1 ’’ in Method 3 is better than in Method 2 and slightly worse than in Method 1.
4. Conclusions
The goodness of the spectral mismatch indices can be evaluated against SMCF by using
multiple different methods. Therefore, when revising the definition of the index for LED
lighting purposes, it is useful to consider the evaluation method. We found out that by using
the standard deviation of the SMCF-1 values for each photometer, we can achieve high linear
correlations with all the indices tested. This method achieves similar or better results than thepreviously used method that uses the mean value of the absolute values of SMCF -1.
Acknowledgement
The work leading to this study is funded by the European Metrology Programme for Innovation
and Research (EMPIR) Project 19NRM02 RevStdLED. The EMPIR programme is co-financedby the Participating States and from the European Union's Horizon 2020 research andinnovation programme.

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POSTERPRESENTATIONS
Tuesday, September 28, 17:45-19:15

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PO01
CHROMATIC LIGHT FIELD EFFECTS ON PERCEIVED MODELLING AND COLOURHARMONYYu, C.1, Eisemann, E.2, Wijntjes, M.1, Assen, J.J.R. van1, Pont, S.C.1
Perceptual Intelligence Lab (π–Lab), Faculty of Industrial Design Engineering, Delft
University of Technology, Delft, THE NETHERLANDS, 2 Computer Graphics and Visualization
Group, Faculty of Electrical Engineering, Mathematics and Computer Science, Delft Universityof Technology, Delft, THE NETHERLANDS
c.yu-2@tudelft.nl
1

Abstract
1. Motivation, specific objective
The light field describes the spectral energy of light in every direction at every point in ascene, capturing all optic information of the lighting distribution. Depending on the complex
interactions between illuminants, surface properties, and scene geometries, the direct andindirect lighting can have different spatial, directional, and spectral properties. A chromatic
environment will—even under a white direct light source—contain chromatic indirect lighting.
In such environments, even a uni-chromatic matte object can show remarkable luminance andchromatic gradients over its surface.
Human observers are sensitive to such luminance and chromatic gradients. Our visual system
uses luminance gradients as cues to infer the structure of light fields, called visual light fields.
Luminance gradients are known to strongly influence "modelling" or how articulated shapes
look. Modelling here refers to revealing three-dimensional forms and textures rather thanconstructing geometries or a representation of something. Research has shown that theperception of three-dimensional shape modulates the perception of the chromatic gradients
arising from inter-reflections. In this study, we tested whether chromatic gradients —in addition
to luminance variations—affect perceived modelling.
When a colour combination of such gradients produces a pleasing effect, it is said to beharmonious. Previous research has shown that perception of colour harmony is dependent on
a complex interplay between lightness, chroma and hue. However, these studies were limited
to abstract co-planar stimuli. It is not clear whether these results with two two -dimensional
uniform colour patches with neutral grey backgrounds generalize to three -dimensional
conditions.
Here we present a psychophysical study testing the influence of light -field effects in a threedimensional scene on object modelling and colour harmony perception. To this aim we
systematically varied the chromaticity of a matte sphere object and the panels of the box inwhich this sphere was placed. This box had a single white illuminant in the ceiling which
together with the chromatic variations allowed for controlled changes of the chromatic light field properties and the luminance and chromatic gradients over the sphere. We thoroughly
analysed the roles of diffuseness, luminance contras ts, and colour distances across regionsof the object and surrounding background.
2. Methods
The experiment was conducted on a calibrated EIZO CG277 LCD (size: 27”) in a darkened
room. To ensure colour consistency across the experiments, the monitor was ca librated to acorrelated colour temperature of 5500 K and a luminance level of 100 cd/m 2 . Observers sat 50
cm away from the display.
The stimuli were pictorial representations of three-dimensional windowless box spaces (with alength, width and height of 6000mm  3300mm  3300mm) rendered with uni-chromatic
surfaces. A coloured sphere (with a radius of 350 mm) was located in the centre of the space.

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The visual angle subtended by the stimuli was 24°. The scene was illuminated by a planar
equal-energy white illuminant (1884mm  773mm).
Across the stimuli, we varied the surface spectral reflectance of the uni -chromatic room andthe sphere. 24 room surface colours were sampled systematically in sRGB space. The
sphere’s colour was selected from the 15 CIE CRI tes t colour samples (TCS).
Observers had to rate perceived sphere modelling (ranging from flat disk to sphere) andcolour harmony (ranging from disharmonious to harmonious) of the gradient over the renderedsphere. Before each session and between trials, participants adapted to a 50-hertz animatednoise mask. At the start, a collage of randomly selected stimuli was presented to provide an
overview, followed by a training session of 15 trials for interface familiarization, before starting
the main experiment.
3. Results
The observers’ scores were determined by mapping the ratio of the distance from the left endof the scale to its full length to values ranging from 0 to 1. The inter -observer agreement
evaluations indicated good levels of response consistencies for both modelling (RMS %CV =16.8%) and colour harmony (RMS %CV = 17.8%).
The modelling scores in low-lightness coloured rooms were relatively higher than in high lightness rooms. The paired t-tests between low-lightness and high-lightness coloured roomsof the same hues (six total) showed that those differences were all significant ( p < .001). The
modelling scores for the blue and yellow coloured rooms were highest and lowest,
respectively, in comparison with the other room hues. Perceived modelling corre lated with theMichelson contrast and even stronger with the colour difference (ΔE00) between spherehighlight and body shadow (r(358) = .62, p < .001 and r(358) = .76, p < .001, respectively).
The diffuseness of the local light field showed a negative cor relation with the modelling score(r(358) = -.76, p < .001).
The colour harmony scores in the coloured rooms with high purity were overall lower thanthose for the lower purity (paired t-test, p < .01). For low-purity cases, the colour harmony
scores were higher for smaller chromatic distances between room and sphere. Among various
room hues, blue had the highest harmony score; green received the lowest. Observers’
harmony scores and scores predicted by the model developed for co -planar stimuli did notagree (r(358) = .11, p < .05).
4. Conclusions
Both a stronger luminance gradient as a result of a less diffuse light field, and a chromatic
gradient due to larger colour differences enhanced modelling perceptions. Colour casts ofinter-reflections with low luminance resulted in better perceived modelling. Reducing thepurity of the room colours enhanced the perceived colour harmony.
These results demonstrate that chromatic light field effects due to (inter -)reflections indeed
have systematic effects on perceived modelling and colour harmony of 3D objects. Our results
for three-dimensional scenes were found not to be consistent with findings based on abstract
co-planar stimuli. These effects show the importance of 3D versions of colour checkers forlighting designers, architects and computer graphics applications, for which we propose
simple Lambertian spheres.

Acknowledgement
This project has received funding from the European Union’s Horizon 2020 research andinnovation programme under grant agreement no. 765121; project “DyViTo”.

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PO03
TOWARDS AN AVIAN FLICKER VISIBILITY MEASURE
Dragan Sekulovski, Malgorzata Perz, Aaron Stephan1Signify, NETHERLANDS
dragan.sekulovski@signify.com

Abstract
1. Motivation
The development of Light Emitting Diode (LED) lighting has put renewed emphasis on thequality of the produced light, targeted to specific applications. As LEDs have a much faster
temporal response compared to traditional light sources, si gnificant emphasis has been put on
the perception of light that changes over time (Temporal Light Modulation, TLM) and themultitude of unwanted perceptual effects due to modulated light (Temporal Light Artifacts,
TLAs).
CIE has been at the forefront of new development in this area. TC 1-83 has been working onclassification and definition of different TLAs (flicker, the stroboscopic effect, and the phantom
array effect) as well as the developments of models for predicting their visibility. All thisdevelopment has, however, been concentrated on the effects of TLM with regards to humanperception. Not surprisingly, the translation of these models to ones that predict the perceived
quality of light for other animals is not trivial.
One of the animals often reared under artificial lighting is the domestic chicken. To the best of
our knowledge, there is no accepted standard way of quantifying the temporal quality of lightfor applications in the poultry industry. This paper aims to remedy that by proposing ameasure of temporal light quality for poultry based on existing models of human temporal lightperception while accounting for differences between human and bird perception.
2. Methods
CIE TC 1-83 defines three different types of TLAs, depending on the motio n of the observer orthe objects in the environment. Among those, flicker is the most critical, meaning that it cancause both discomfort and unwanted health effects. For instance, it can trigger migraines. The
unwanted effects of flicker on humans have been described in detail in the literature. For
humans, the visibility of flicker is limited to frequencies of up to around 80 Hz, with theprobability of critical health effects being significant only below a frequency of around 50 Hz.
Due to its critical nature, the CIE as well as national regulatory and performance standards
require TLMs to be limited to amounts that do not produce any visible flicker. Because TLM inlighting applications is typically aperiodic, it is recommended to use a time domain metho dwith statistical processing for the quantification of the perceived flicker.
Temporal characteristics of birds’ visual perception are not as well understood as those ofhumans. However, several psychophysical studies have been designed and reported in th eliterature, typically using a concept of the Critical Flicker fusion Frequency (CFF, being afrequency above which light modulation is not detectable).
It has been demonstrated that birds’ CFF is higher than humans CFF (i.e., 80 Hz). For somepasserine species (blue tit and flycatcher) CFF has been reported up to 145 Hz, and fordomestic chicken, up to 105 Hz. Some behavioural responses to high frequencies only occurin brighter light, for instance the increased CFF of chicken is especially pronounced ab ove
50 lx, showing that CFF is. light intensity dependent. Intensity dependence of CFF is alsopresent when measured by an electroretinograms (ERG) of normal laying hens, with the
maximum frequency discerned at 119 Hz.
As with humans, visible flicker might negatively impact the health or well-being of birds. These
have been estimated using behavioural responses, such as preference and activity (e.g.,

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eating, jumping), and by measuring hormone levels, such as corticosterone, which is anindicator for stress. Not all studies yield consistent results, however it is apparent that
exposure to light modulated at frequency of 100 Hz has negative impact on starlings, relative
to 30 kHz light. In 100 kHz light starlings had lower basal corticosterone levels, and hig herlevels of myoclonus (involuntary muscle spasms) and preening compared to 30 kHz light. 100
Hz light also led to reduced jumping, eating, drinking and bill wiping in starlings. This
indicates chronic stress, which continued after exposure to relatively low-frequency light
modulation.
3. Results
One of the models recently used for the characterization of flicker in the time domain is basedon a proposal of Fredericksen and Hees (1998). It is a physiologically inspired model thatuses weighted probability summation of two responses, first from a lowpass exponential filter
then a second bandpass filter, which is the second derivative of the base exponential filter.
Besides being predictive of physiological outcomes, this model has an additional advantage of
having a small number of parameters.
In this work, we propose a modification of the existing human flicker model that changes theparameters of the base model in a way that uses the differences between human and bird
vision. As most literature on temporal vision in birds measures CFF, the parameters are tuned
to produce a model corresponding to a CFF of 150 Hz with a relative shape equivalent to theone of the model for human flicker perception. We further discuss the responses that the
proposed model produces for a number of light sources used in literature studies as well as
being used in the market at the moment.
4. Conclusions
The current paper proposes a measure of temporal light quality that could be used to design
flicker-free LED sources, as perceived by birds. It can be applied in, among others, thepoultry industry to reduce the negative impact of the modulated light on chicken health andwell-being.

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PO04
ARE THE DEMANDS IN ENTERTAINMENT LIGHTING TOO HIGH FOR WHITE LIGHT
EMITTING DIODES?
Nilsson Tengelin, M., Mylly, N.
Department of Measurement Science and Technology, RISE Research Institutes of Sweden,Borås, SWEDEN
Maria.Nilssontengelin@ri.se

Abstract
1. Motivation, specific objective
In the European Ecodesign Directive EU 2009/125/EC and in the superseding regulation EU
2019/2020, specialized lamps and fixtures for entertainment lighting are exempt from someparts of the regulation, e.g., enabling a continued use of tungsten filament light bulbs and arc
lamps in this field. Halogen lamps are still widely used in lighting of museums, theatres andexhibitions. One reason for this is that lighting systems with specialized luminaires and control
systems are expensive and replacing an existing system is therefore a very large undertaking.
There is also a substantial insecurity regarding the procurement and specification ofrequirements. Among the lighting professionals working at theatres, with performing arts, andin museums there is also a widespread conception that the Light emitting diode (LED) ligh tingtechnology replacing the traditional halogen lighting systems are lacking in quality in several
areas. This includes poor colour rendering, flicker issues, inconsistent behavior duringdimming, colour change with ageing and other unwanted properties, making the replacementof existing lighting systems both an economic as well as an artistic challenge. Thus, with theaim of lowering the energy consumption, phasing out the incandescent lighting and facilitate atransition to LED lighting technology, the Swedish energy agency has financed a research
project on the white light LEDs used for entertainment lighting. The project includes surveys
and workshops to identify the requirements and special demands the industry has for thequality of the white light, guidelines for procurement and a dictionary with words and concepts
related to entertainment lighting for better understanding and communication between lighting
suppliers and lighting professionals. The project is a collaboration between the industry,entertainment lighting professionals, the national heritage board and a national research
institute. Even if the entertainment industry often is hesitant about modern lighting systems,
they realize the importance of being as prepared as possible for the techn ology change as theregulation exempts most likely will be removed in the future . The aim of the project is tosupport the suppliers and the end-users with knowledge so that they will be able to acquire
LED entertainment lighting that meet their expectatio ns. The specific objective of this paper isto report the result of the first survey performed within the ongoing project.
2. Methods
In August 2020 a survey was sent to 246 museums and 56 theatres in Sweden. A total of 39
museums and 31 theatres replied to an online questionnaire. The questions concerned thelighting technology used in the respective establishment, experience from changing thelighting from halogen to LED, plans for the lighting in the future and possible problems,apprehensions and expectations
3. Results
The result showed that museums are significantly more positive to LED lighting technology
than theatres. The museums have already replaced 50% of their lighting with LED while over
60% of the lamps in theatres are halogen. For stage lighting only one of four lamps is LEDbased. Of all theatres, only 3% have transitioned to LED lighting, and 35% say that they are
not planning to replace their current lighting with LED in the future. Of the museums 28%
have replaced their incandescent lighting to LED and the remaining 72% plan to do so in the
future. Of the ones planning the transition to LED, many of the theatres are hesitant andwaiting for the technology to improve. The main reasons not to consider LED is the cost and

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fear of poor light quality. LED-products are simply not considered priceworthy. Also, issues
regarding the function when dimming was often mentioned as a major obstacle .
Of the institutions that are using LED-lighting, the museums are overall much more satisfied
than the theatres. The institutions that plan to replace their lighting have not yet done so
because of economy, lack of time and resources or because they are questioning the current
technology and are waiting for the products to improve.
4. Conclusions
In conclusion, the largest impediments for a transition to LED lighting among the institutions
positive to the technology is the financial cost and the lack of knowledge on how to specify
the requirements. The theatres that are against a transition to LED lighting pinpoi nts possible
quality issues and are especially skeptic about the light quality. The impression is that thelight from LEDs will have inadequate colour rendering properties and interact differently withdisplayed materials, human skin, make up etc. compared to light from halogen lamps. The
general impression is that the LED lighting gives an unnatural appearance and hampers theartistic expression. To facilitate a smoother transition to modern lighting technologies, thequality of the white light and proper function of the luminaires must be ensured and thecommunication between the manufacturers, retailers, lighting professionals and other artistic
functions must be improved.

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PO05
OPTIMUM SPECTRUM OF LED LIGHTING FOR CULTURAL AND HERITAGE SITE: A
CASE STUDY OF 15TH CENTURY WORLD HERITAGE SITE IN NEPAL
1

Bista A.1,2, Bista D.1,2
Department of Electrical and Electronic Engineering, Kathmandu University, 45200 Dhulikhel,
NEPAL
2Center for Electric Power Engineering (CEPE), Kathmandu University, 45200 Dhulikhel ,NEPAL
aayushbista@ku.edu.np

Abstract
1. Motivation, specific objective
Various architecturally and culturally rich heritage sites are in the Himalayan country Nepal.
These culturally important sites consist of artifacts and monuments made of wood, bricks,
stone, traditional materials etc. The structure and monuments are rich with carvings of Hindu
and Buddhist deities. Tourists visit these UNESCO World Heritage listed sites to admire thearchitecture constructed centuries ago. Over the last few years, massive transformation has
been observed after the 2015 earthquake. Projects for reconstruction of physicalinfrastructures are in operation and some efforts for intervening artificial lighting has been
observed. Current lighting schemes are not appropriate technically and bring several
problems like high power consumption, luminaries obstructing the view of the architecture,
misleading colour perception, dark and bright spots, glare etc.
One of the key aspects of lighting in a heritage site is visual perception and lighting efficiency.
Visual perception of any object is determined by both illuminance and surface luminance.
Material colour will influence the value of surface luminance and vary with the spectral
composition of projected light. The paper focuses on finding out optimum spectrum RGB
controlled LED light to obtain high luminance when projected on construction materials of theheritage site. The paper also considers aspect of energy efficiency and recomm ends optimum
RGB power proportion to reduce energy consumption.
2. Methods
The research commenced with the design of light sources of different SPD and CCT. This wasachieved by balancing the Red, Green and Blue component of light source. Materials used in
the construction of Nepalese heritage site were collected from Bhaktapur Durbar Square (a15 th century old palace listed in UNESCO World Heritage Site). These materials were
illuminated with different types of light sources (CCT of 1500K to 7000K). The il luminance atthe surface of the object was kept constant for all sources. As a next step, the surface
luminance (cd/m 2 ) of the illuminated material from various light source were measured. The
comparison of the illuminance and spectral power of the light s ource along with thereflectance (luminance) from the surface help analyse the optimal light source for theconstruction material used in cultural and heritage site of Nepal.
3. Results
Different materials: bricks, carved bricks, tiles, carved wood, stone, carved stone from
Nepalese heritage sites were used for the research purpose. They were illuminated withvarious RGB spectrum of light. Different material showed different luminance properties
varying with spectrum of light. Light source with the same ill uminance and spectrum had
different luminance (cd/m 2 ) on different objects based on their reflectance properties. Also, an
object, when illuminated with a different spectrum, had a different level of power consumed,
keeping the luminance from the object constant. The trade-off between luminance from theobject or how bright the object seems and the power consumed is analyzed.

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4. Conclusions
Nepalese heritage sites have various special building and these special buildings require a
special light source. Tuning the RGB spectrum of LED light to optimum spectrum for the
heritage sites of Nepal not only saves significant power but also makes the art of historicplaces aesthetically pleasing. This research identifies the light source optimum to Nepalese
heritage sites and suggests a sustainable light source for different materials used in heritage
sites.

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PO06
DESIGN TRADE-OFFS FOR MULTI-PRIMARY BASED LIGHT SOURCES
Whitehead, Lorne
University of British Columbia – Department of Physics and Astronomy, Vancouver, CANADA
lorne.whitehead@ubc.ca

Abstract
1. Motivation, specific objective
The spectral power distribution (SPD) of a white light source can be characterized in several
ways, including luminous efficacy of radiation (LER), chromaticity, and colour fidelity.
Generally, there is an inverse relationship between luminous efficacy of radiation and colour
fidelity. This warrants careful attention, especially for light sources that blend high chroma“primary” lamps to yield white light.
For these multi-primary light sources, a key design decision is the number of primaries, N. A
simple chromaticity match is possible for N=3, but this makes it more difficult to achieve adesired level of colour fidelity, especially for primaries having a narrow bandwidth, which canbe advantageous for other reasons.
Importantly, colour fidelity is a complex topic, which includes three quite different concepts.
The first (and best-known) concept could be viewed as “standard” colour fidelity, and is the
only one currently in common use. It is inaccurately quantified by the historic CIE R a , and is
now accurately quantified by the CIE/IES R f . R f assesses the perceived colour difference
between (i) a test surface observed under a test source and (ii) the same surface observed
under a chromaticity-matched standard reference source. The R f calculation averages thesize of colour differences calculated for 99 test surfaces and assigns an R f score between 0
and 100. If R f =100 there are no colour differences, while a score of 90 corresponds to al mostall of the test surfaces matching very well between the two sources.
The second key aspect of colour rendering involves metamerism error – the phenomenon
whereby two objects with different spectral reflectance factors, which appear the same colourwhen viewed by a standard observer under a standard light source, are perceived as differingin colour when viewed by the same observer under a different, but chromaticity matched, test
source. This effect can be disturbing because colour-matching is highly valued in many
situations. This has been addressed in recent scientific literature, where the term R t has been
proposed to represent this effect, on a scale similar to the one used for R f .
The third aspect involves the natural diversity of cone fundamentals among colour-normal
observers. Typically, an individual’s higher vision system compensates well for moderate cone
differences, yielding colour perceptions that are largely consistent with those of an averageobserver. However, that compensation can be defeated partially by illumination from nonstandard light sources. Investigations are underway to better assess the extent to which agiven SPD could impair the colour perception of diverse colour -normal observers. The term R d
has been suggested for assessing this aspect of colour fidelity error, again on a scale similar
to that used for R f .
To date, of these three important aspects of colour fidelity, only R f has been considered in
optimizing the SPD design of light sources, but quite likely R t and R d are just as important andperhaps more so. Certainly, there is no known reason to believe these are negligible effects –likely they have been ignored previously because there has been limited knowledge of theunderlying physiology and a tendency to rely on his toric averages to represent all observers.
The motivation of this study is to argue that these considerations are important for optimizing
multi-primary light sources, suggesting that significantly more work in this area is urgently
needed.

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2. Methods
To help support this perspective, multi-primary light sources were studied theoretically. Eachcomprised a feasible set of N primaries that are Gaussian SPDs. For each, the peakwavelength, standard deviation, and intensity were allowed to vary, while being co nstrainedso as to yield, for this analysis, a CCT value of 4000K and D uv of 0. For any selected value of
N and any reasonable target value for R f , there is a unique set of values for these variables
that yields the highest possible value of LER subject to those constraints. Finding thatsolution is a complex iterative computational problem, but fortunately it is a practical one
because the standard CIE calculator for R f , (which is at the core of the optimization algorithm),
is non-iterative and therefore quite fast.
It is generally recognized that if the R f value of an SPD is 90, there is often very little
noticeable colour error, but that omits consideration of R t and R d . While there is not yet an
official CIE procedure for assessing those two additional aspects of colour fidelity, they are
known to have a magnitude similar to R f , with partial correlation. Therefore, as an
approximate, conservative approach for taking them into account in this study, the target
value for R f was set to 95, such that even with the eventual inclusion of R t and R d , goodcolour fidelity should be assured.
3. Results
Using 6 primaries, the resultant LER is 343 lm/W, which is very nearly the theoretical limit of
344 lm/W, for this chromaticity. In this case, the standard deviatio ns of the six primaries arequite low, (about 7nm), at least for the shortest wavelength primary and also the longest
wavelength one. This helps to achieve a high luminous efficacy by minimizing emission in thevery low efficacy portions of the visible wavelength band.
An important consideration is that, for practical reasons, it could be desirable to use fewer
primaries. However, this becomes increasingly problematic as N is reduced, because thespacing of the primary peaks consequently increases, and ther efore so must the standard
deviations, in order to sufficiently minimize the spectral gaps that would otherwise diminish
colour fidelity. The net result is that as N is reduced, successively, to 5, 4, and 3, the resultant
LER decreases, respectively, to 341, 335, and 329 lm/W.
4. Conclusions
Generally speaking, white light sources based on high chroma primaries could play a valuablerole in lighting, by optimizing the trade-off between luminous efficacy of radiation and colour
fidelity. However, neither 3-primary nor 4-primary systems are beneficial from this perspective.
Generally, the best combinations of LER and colour fidelity can be achieved by using 5 or,ideally, 6 primaries.

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PO08
SPECTRAL TRANSMISSION AND SCATTERING CHARACTERISTICS OF HUMAN SKIN
1

Akizuki, Y.1, Kanke, K.1, Osumi, M.2
University of Toyama, Toyama, JAPAN, 2 Office Color Science, Yokohama, JAPANakizuki@edu.u-toyama.ac.jp

Abstract
1. Introduction
At the time of major disasters, crush syndrome is prone to occur at debris. Disaster victims go
into shock and peripheral hypoperfusion, and then their skin colour changes whiter especiallyat the spectral reflectance from 500 to 600nm which is linked to the absorption by hemoglobin.
For emergency medical care, it is important to disting uish the colour change of patients inworsening health condition. Therefore this research project aims the development of skinsamples reproducing various symptoms and light sources in order to distinguish their colour
differences.
Our previous paper reported a procedure of making better urethane skin samples which had
spectral reflectance factors close to real human skin colour data by using a method ofcomputer colour matching. However, it is necessary for the appearance of human skin sample
to deal with not only the spectral reflectance characteristics but also the multi -layer structure
and translucency. Therefore we measured and analyzed the spectral transmitted andscattering light characteristics for this study.
2. Methods
A spectroscopic imaging system was used in this research experiment, which wasdevelopment by Office Color Science and could be measured in two dimensions with an
optical fiber. The lens (M23FM50) with 50mm focal length and the aperture of F2.8 -F32 is
made by Tamron Co. Ltd., and we set F4.0 in order to keep aberrations under control.
VariSpec Liquid crystal tunable filters made by PerkinElmer/CRI is captured twenty -nine
spectral bands between 420 and 700nm by 10nm. CCD imaging sensor (BH -60M) made by
BitRAN Co. has anti-blooming mechanism and Peltier cooling system. The light receiving
surface areas is 28.5-by-21.4, and the image resolution is 688DPI (772-by-580 effective pixel)
with 16 bit. Lighting LED made by CCS Inc. has high colour rendering properties, and thespectral distribution is almost even at optical wavelengths. This spectroscopic imaging system
optimizes the wavelength performance automatically at the time of proofreading in order tohomogenize dynamic range of measurement wavelength band, for instance it adjusts
exposure longer at 420nm. This spectroscopic imaging system has three modes ofmeasurement; (1) proofreading mode by a integrating sphere measurement, (2) mode tomeasure the transmitted and scattering light intensity by an optical fiber, (3) mode to measure
the spectral reflectance at the measured angle of 15 degree and 45 degree by the optical fiber.
The transmitted and scattering light intensity which propagated through skin was measured bythis spectroscopic imaging system. Then the attenuation by distance f rom the optical fiber
was calculated from the light intensity results. The spectral reflectance characteristics of skinsurface was also measured by same spectroscopic imaging system.
Five subjects participated in this experiment. They differed in age, ge nder, and Body Mass
Index (BMI). The optical fiber was closely placed on subject’s anterior surface of the forearm.
3. Results
For any subjects, the maximum of transmitted and scattering light intensity was resulted at
700nm, and decreased with decreasing wavelength. Under 550nm, the light intensity
perceived by this spectroscopic imaging system was very faint. These results showed somecorrelation with image results of spectral reflectance of skin surface. There were personal

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differences on the distance from the optical fiber until transmitted and scattering light intensity
was down to zero.
Having analyzed the attenuation ratio per unit distance from change of the transmitted andscattering light intensity, all subjects showed the peak of the attenuation r atio at 700nm, and it
decreased with decreasing wavelength. Moreover, for the relations with BMI, the attenuation
ratio showed positive correlations with BMI.
4. Conclusions
In the near future, we will make it a goal to reproduce human skin samples more ac curately byadjustment to the concentration of mixed colour pigments and the structural reform for two layer, with consideration for individual differences of the transmitted and scattering lightintensity.

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PO09
PERCEIVED CHROMA AND HUE CHANGES OF COLOURS AT HIGH ILLUMINANCELEVELS DUE TO HUNT EFFECT
Kawashima, Y., Ohno, Y.
National Institute of Standards and Technology, Gaithersburg, MD USA
yuki.kawashima@nist.gov

Abstract
1. Objective
The Hunt effect is the perceived chroma changes of object colours at different light levels.
The chroma of object colour is perceived less saturated at a lower light level than at a higher
light level. Therefore, to bring the appearance of the object at normal indoor lighting to beclose to that at outdoor daylight, the chroma of the objects need to be increased by lighting,as the outdoor daylight normally has much higher light level than the indoor lighting. Although
the perception to increased chroma has been considered as a matter of preference in the paststudies, it would be a matter of colour fidelity if the object colours at the outdoor daylight areconsidered as a reference for colour appearance of objects. Since the Hunt effect is notconsidered in the colour fidelity metrics currently used (CRI or 2017 CIE Colour F idelity Index),
it needs to be taken into account in a new fidelity metric. Our previous study quantitatively
showed the perceived chroma changes by the Hunt effect using 100 lx and 1000 lx lights(paper in CIE Expert Symposium 2020). Further, it was also found that the hue angles slightly
shift in each colour between the two light levels. However, there has been no data on the
degree of the Hunt effect between 1000 lx and the outdoor daylight illuminance level. The
purpose of this study is to quantify the chroma change by Hunt Effect for such highilluminance levels, using experimental lights at 1000 lx and 6000 lx, and also measure theperceived hue shifts.
2. Methods
A double-booth was used for the experiment. Each booth is equipped with several highcolour-rendering index (CRI) dimmable LED lamps with nominal correlated colour temperature(CCT) of 5000 K and the CRI Ra of approximately 95, and nominal electrical power of 11 W.
Each side of the booth could be set to approximately 6000 lx with their full power or 1000 lx
by using two of these lamps with dimming control. The high illuminance and low illuminancesettings were swapped for the left side and right side of the booth. The small chromaticity
differences between the left side and right side of the bo oth in each setting were adjusted towithin 0.0008 in  u’v’ by using a 16-channel spectrally tunable light source originally installedin each side of the booth. The lights for both sides were measured to be at colour ≈ 4800 K
with Duv (distance from Planckian locus) ≈ -0.0002.
A set of 20 test colour patches for one colour, each patch 6.5 cm × 6.5 cm in size, wasarranged in 5 rows × 4 columns, for four hue angle shifts horizontally and five chroma shifts
vertically, placed on a board (28 cm x 34.5 cm size). The test colour boards were prepared for
four colours (red, green, blue, and yellow), each of which was placed in one side of the boothat 6000 lx, and a reference colour patch in each colour, which is the same size and the same
colour as one of the test colour patches (2 nd from maximum chroma level) was placed on theother side of the booth at 1000 lx.
Each set of test colour patches had a range of chroma difference of Δ C a’b’ ≈ 10 with intervalsof ΔC a’b’ ≈ 2.5 in CIECAM02 colour space for red, ΔC a’b’ ≈ 12 with intervals of ΔC a’b’ ≈ 3 forother colours. The range of hue angles was ≈ 9° with intervals of ≈ 3˚ for red, yellow andgreen, and the range of ≈ 15˚ with intervals ≈ 5˚ for the blue set because hue differences of 3˚
for blue was hardly perceivable. These specifications were determined by preliminary
experiments and our experience in previous experiment. The patches were produced with athick matte paper printed with a 12-ink professional printer. The colours of patches were
adjusted by repeated measurements and re-printing.

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Seven subjects so far, having normal colour vision, have participated in the experiment. The
number of participants is limited due to difficulty in Covid -19 but recruiting subjects continues
with a hope that Covid-19 situation may improve, and we expect to have total 15 subjects tocomplete this study. We used special procedures to run this experiment for Covid -19 safety,
running experiment remotely so that the subject is alone in the lab and instructions were given
through an on-line meeting tool. The demonstration of the procedures is given by a video prior
to the experiment.
The subject sat with his/her forehead against a view divider in front of the centre wall of thebooth so that each eye viewed only each side of the booth (haploscopic view). The subject
was adapted to the illumination of each side of booth for five minutes before experimentstarted, during which Ishihara colour vision test was done and the subject had a practice runusing one of the test colour boards. After adaptation, the first colour patches were set in thebooth, and the subject was asked to select a matching patch (at high illuminance side) thatappeared closest to the reference patch (at low illuminance side). As the colour under lower
illuminance appears less saturated, subjects would typically select a ma tching patch that isless saturated compared to the reference patch. The effect of the Hunt Effect can bequantified from the chroma difference between the selected matching patch and the reference
patch.
As a part of this experiment, since each eye will not be perfectly adapted to very different lightlevels at haploscopic condition, a set of 6 grey patches of slightly different lightness ( J’ ≈ 67
to 74) and a reference grey patch (J’ ≈ 74, the same as the lightest grey in the 6 grey patches)
were prepared, and the subject selected a matching grey patch at higher illuminance side
after full adaptation The results of this grey matching were us ed to correct the experimental
results for imperfect adaptation in haploscopic condition. Typically the test patches withJ’ ≈ 74 to 72 were selected by the subjects, showing some individual variations.
3. Results
The mean differences in chroma and hue angle between the reference patch and the selected
matching patch for each colour was calculated for the seven subjects done so far. The mean
chroma of the selected matching patch was 0.2 to 0.8 units in ΔC a’b’ or 0.4 % to 1.9 % lower
than the reference patch, depending on colour of patches. These results mean that the colour
patches at 1000 lx appear slightly less saturated than those at 6000 lx, however, thedifferences were much smaller than the results of previous study between 100 lx and 1000 lx(4 to 6 units in C a’b’ or 8% to 15% in chroma). The changes in hue angle were from -3.2° to
1.3°, which are also smaller than those in the previous study ( -4° to 7°) and most significant in-3.2˚ for red.
4. Conclusions
Changes in perceived chroma and hue angle by the Hunt Effect between 1000 lx and 6000 lx
were experimentally quantified for four different colours. 6000 lx was used as an illuminanceclose to outdoor daylight condition, with a purpose of providing the perception data of theHunt Effect from 100 lx to 6000 lx, a level close to outdoor illumination levels, by connecting
the results of previous study done between 100 lx and 1000 lx. The results showed that theperceived chroma changes between 1000 lx and 6000 lx are much smaller (average ΔC a’b’less than 1 unit) and insignificant compared to the results between 100 lx and 1000 lx found in
our previous study. Small hue angle changes were also observed. These data will be usefulfor developing a colour fidelity model based on the Hunt Effect using the outdoor daylight
condition as the reference, and may lead to an improved tool or a metric for evaluating colour
rendition of light sources. The number of subjects in this experiment was limited due to Covid 19 situation. The experiment is still to continue with additional subjects to increase thenumber, and thus, increase robustness of the results of this study.

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PO11
VISUAL EFFECTS OF OBJECTS UNDER METAMERISM WITH MULTI-SPECTRAL
LIGHT SOURCE
Li, Y.M. 1, Fan, H. 2, Lin, C.H. 3, Chong, J.U. 4, Lee, T.X. 5
Graduate Institute of Applied Science and Technology, National Taiwan University of
Science and Technology, Taipei, CHINESE TAIPEI, 2 Department of Drama and Theatre,
National Taiwan University, Taipei, CHINESE TAIPEI, 3 Department of Geography, National
Taiwan Normal University, Taipei, CHINESE TAIPEI, 4 Department of Chinese, National
Taiwan Normal University, Taipei, CHINESE TAIPEI, 5 Graduate Institute of Color andIllumination Technology, National Taiwan University of Science and Technology, Taipei,
CHINESE TAIPEI
txlee@mail.ntust.edu.tw
1

Abstract
1. Motivation, specific objective
Many stores have used lighting control to increase the colou rful of goods, it’s traditional often
used colour rendering index (CRI) to evaluate. However, in recent years, many studies havepointed out that the CRI is different from the visual effect of real human eyes, and thenscholars have developed colour quality scale (CQS). This study attempts to simulate themetamerism colour, and analyse the influence of light source on the visual effects, anddiscuss with CRI and CQS relationship.
2. Methods
In this study, the guava was used as the target object, and we design four sets of metamers
with a correlated colour temperature of 4000K and an illuminance of 750lux. The light source
was simulated in the LED cube, and the subjects with convenience sampling observe thevisual effects (include look delicious, colourful, and colour rendering) of guava undermetamerism, and then analyse its relationship with CRI and CQS.
3. Results
The results of the study show that the subjects have significant differences in preferences forguava under metamerism, and the statistical analysis of colour rendering and visual effects is
not a positive relationship, and more importantly is the composition of the spectrum, which
has more green spectral is the best in this study case. Further, compare the effects of CRI
and CQS, the CQS were closer to the visual effects of subjects.
4. Conclusions
This study, conducted experiments with four sets of metamer light sources. The results
showed that colour rendering and visual effects is not a positive relationship, and the effect of
CQS is closer to the visual effects of the subjects. The results of this study can be used as areference for light source lighting designers as a basis for improving lighting conditions. In the
future, we can collect database for different object with optimized multi -spectral light source.

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PO12
APPLICATION OF A STATISTICAL APPROACH TO THE DESCRIPTION OF COLOURPERCEPTION THRESHOLDS
1Rybina, V.A., Grigoryev, A.A.1
VNISI Russian Lighting Research Institute named after S.I. Vavilov, Moscow, RUSSIAN
FEDERATION
torybigfish@gmail.com

Abstract
1. Motivation, specific objective
The main scientific area, in which the authors work, is the creation of a statistical model of thethreshold colour vision. In the course of their scientific work, the authors considered problems
related to the colour vision.
2. Methods
The statistical model allows the authors to calculate thresholds of the colour differentiation ofobservers if the spectral sensitivity of receptors is known. They determine a shape and an
orientation of threshold ellipses in the colour space.
3. Results
In this project, we will present calculated ellipses similar to the experimental MacAdam
ellipses. For their construction, the authors used the spectral sensitivity of receptors ofobservers with normal colour vision, which were obtained with a new method under conditionsof constant colour adaptation.
The authors have developed the uniform colour space in which all threshold ellipses aretransformed into points of one circle with a unit radius. Different chromaticity correspon ds todifferent locations of threshold points on this circle.
4. Conclusions
The proposed uniform colour space differs from the known ones in that it reflects not so muchabout colours themselves as the difference between colours of two objects.

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PO13
SUBJECTIVE EVALUATION OF VISUAL COMPLEXITY, CLARITY, AND PREFERENCE
OF INDOOR ENVIRONMENTS
Wang, E.1, Durmus, D.1
Penn State University, USA
ykw5337@psu.edu

Abstract
1. Motivation, specific objective
Visual perception is a multidimensional phenomenon that inf luences visual comfort, task
performance, and the satisfaction of observers through its dynamic attributes. The perceived
quality of the visual environment can be investigated in terms of visual complexity, visualclarity, preference (satisfaction), and overall quality. Visual clarity is affected by luminanceand chromatic contrast in the visual environment. Visual clarity can also be defined as
distinctness and clarity of details. Visual complexity is related to the forms and structures in avisual image, and it relates to the level of detail and intricacy found within an image. Visualcomplexity can be affected by the number of visual features, colour differences, and contrast
differences. Preference denotes observers’ satisfaction with the overall image.
Previous studies suggested that visual complexity and image quality may be interrelated,
although they are not interchangeable concepts. Both visual complexity and visual clarity areimportant measures, but they have only been investigated using a limited range of lighting
characteristics. On the other hand, computer science and imaging studies often investigate
the overall quality of digital images, but they do no address specific measures related toarchitectural spaces, such as visual complexity, clarit y.
Despite the importance of visual clarity and visual complexity, their influence on preference
and impressions of observers has not been widely investigated. This study aims to answer
two main questions: (1) is there an overlap between preference, visual clarity, and visualcomplexity? (2) How do spatial characteristics of images influence the perceived quality ofindoor environments?
2. Methods
A visual experiment was conducted to test the accuracy of image quality metrics in estimating
the visual complexity, visual clarity, and preference of indoor environments. Fifty images withvarying spatial and chromatic characteristics were collected from online databases in ten
categories: offices, residential spaces, educational spaces, gyms, retail spaces, indus trial
spaces, restaurants, health centers, museums, and houses of worship.
The quality of each image was quantified using computational image quality metrics, including
image sharpness, spatial frequency slope, blind/referenceless image spatial quality evaluator(BRISQUE), entropy, International Telecommunication Union (ITU) spatial information (SI),and detectability suprathreshold R spt . BRISQUE measures the quality of an image without
comparing it to a reference condition (i.e. undistorted version of the same image). A lower
score suggests a higher level of perceptual quality. The ITU SI is a metric that quantifies thespatial detail in an image, and it is based on the Sobel filter and calculated by the standard
deviation over the pixels in each Sobel-filtered frame. It is typically higher for more spatiallycomplex scenes. Entropy is a measurement of uncertainty (randomness) in images. The
higher the entropy value, the more uncertain and detailed the information in images.
Sharpness refers to the overall clarity of an image with regard to focus and contrast. Spatial
frequency slope means the slope of the number of grating cycles per degree of visual angle.
The detectability suprathreshold R spt quantifies the visual complexity of an image based on
the adaptive thresholding method.

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The images were scaled to be the same height (709 pixels) and displayed on a calibrated
display in random order. Participants were positioned 1 m away from the screen, resulting inapproximately 12-degrees of visual field. The vertical illuminance at the eye level was 90 lx,
and the average horizontal illuminance was 110 lx on the desktop at 0.7 m from the floor.
Participants were asked to respond to three questions for each image: preference, visualclarity, and visual complexity. The participants rated each image using a six-point Likert-type
scale with no neutral point. The scales ranged from "Extremely like" to "Extremely dislike" forthe first questions, while the second and third questions were about visual complexity andvisual clarity, ranging from "Extremely simple" to "Extremely complex" and "Extremely
unclear" to "Extremely clear " respectively. In addition, there was a separate “I do not know / I
do not care” option to reduce bias and improve the reliability of the scales. Participants’reaction time for each question was also recorded.
3. Results
The data were analysed to determine the relationship between six image quality metrics for 50
images and participants’ responses and reaction times to preference, complexity, and clarity
for each image. The BRISQUE values ranged between 1.6 and 44.5, ITU SI ranged between
49.4 to 122.8. Sharpness, R spt , spatial frequency slope, and entropy varied from 0.09 to 0.2,
105 to 973, -1.3 to -0.9 and 7.1 to 7.9, respectively.
The preliminary results indicate that visual clarity, complexity, and preference are distinct
concepts, while preference is related less to complexity than clarity. Clear images tend to be
more preferred than unclear ones. Results also suggest that image quality metri cs can beused to assess the visual clarity of indoor environmental images.
4. Conclusions
Understanding and estimating the perceived quality of visual environments have significant
benefits for architectural design and imaging systems. However, the spatial characteristics ofvisual scenes and their influence on subjective evaluations are not widely studied. The
importance of visual comfort and clarity are not widely recognized. Here, two interrelated
questions are identified related to the visual perception of indoor spaces: the distinction
between visual clarity, visual complexity, and preference; and the role of spatial
characteristics in the perception of visual environment quality.
Participants judged the preference, visual complexity, and clarity of 50 images with diverse
spatial characteristics. Six no-reference image quality assessment measures were used toestimate observers’ subjective evaluations. The difference and connection among evaluatedimage metrics, visual complexity, visual clarity, and preference were investigated. Findings
from this study can improve visual impressions and view quality of occupants in indoor
environmental systems and virtual scenes (e.g. augmented reality, virtual reality). Future
research will focus on expanding this work by investigating outdoor images, evaluating otherimage quality metrics, and testing the chromatic contrast hypothesis (redness -greenness,yellowness-blueness).

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PO14
DEVELOPMENT OF A METHOD FOR MEASURING PPFD DISTRIBUTION OVER THE
TECHNOLOGICAL AREA OF A GREENHOUSE BY A MOBILE INSTALLATION
Panin Vyacheslav, Fedorishchev Mikhail
Russian Lighting Research Institute named after S.I. Vavilov, RUSSIA
panin@svsrv.ru, fma@vnisi.ru
Introduction
To ensure optimal conditions for plant growth in the production premises of greenhouses,
high-quality parameters of artificial plant cultivation should be provided. At the moment, due
to the relative ease of measurement and the significant impact on the development of plants,
the main lighting parameter that determines the quality of the use of the irradiation unit is the
PPFD. Due to the complexity and long duration of the measurement process, not the entire
technological area of the greenhouse is examined, but only a small part of it. Thus, the dataobtained in the course of such a survey may not be complete enough for an objective
assessment of the quality of artificial irradiation of plants.
Therefore, there is a need to create a mobile measuring device and a measurement methodthat allows you to measure the PPFD over the entire area of the greenhouse.
Methodology
The method of measurement using a mobile installation makes it possible to measure thenormalized parameters continuously, therefore, to obtain significantly more information thanwhen performing measurements using a stationary control method. The most informative andat the same time economically profitable is the mobile measurement method, which uses anunmanned aerial vehicle with a quantum sensor installed on it to determine PPFD.
Since the irradiance measurements take place continuously while the mobile unit is moving, todetermine the measurement control points, the data coming from the quantum sensor and theunmanned aerial vehicle are combined. These values can already be used to determine thenormalized parameters, since each control point carries information about the measurement
object and has its own individual parameters that allow you to determine its location. But,
since the premises of the protected ground most often have rather large areas, then for an
informative display of the measured values of PPFD, a map of the distribution of PPFD over
the technological area of the greenhouse is created.
Results
A method for measuring PPFD distribution over the technological area of the greenhouse wasdeveloped using a mobile installation. To implement this technique, a prototype mobile
installation was developed, consisting of an unmanned aerial vehicle with a quantum radiat ion
sensor installed on it. The selection of the main elements of the installation was carried out on
the basis of the characteristics of the measurements in the greenhouse premises, taking into
account the microclimatic conditions. In the process of developing the methodology, asoftware product was created that allows processing the measurement results, namely,
calculating PPFD and creating a map of the distribution of PPFD over the technological areaof the greenhouse.
The measurements accuracy was evaluated, according to the results of which the errors indetermining the average PPFD(± 5.6 %) and the distribution of PPFD(± 7.8%) were
established.
A control experiment was conducted to compare the results of measurements with a quantum
sensor at the control points. The largest discrepancy was 2.3 %, and the average difference(across all control points) was 0.9 %.

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Conclusion
In general, the method of measuring the distribution of PPFD over the technological area of
the greenhouse by a mobile installation is of great importance, since it allows you to obtain
the distribution of PPFD over the entire area of the greenhouse, spending less time andresources compared to stationary control methods. Therefore, the measurements carried out
using this method will allow the most qualitative (accurate) assessment of the effectiveness ofirradiation installations, thereby ensuring optimal conditions for plant growth and development.

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PO15
EVALUATION OF IMPEDANCE OF CABLES IN GONIOPHOTOMETRY
Pan Jiangen, Li Qian, Li Xiaoni, Gong Teng
EVERFINE Institute of Optoelectronics, Hangzhou, CHINA
tech@everfine.cn

Abstract
1. Motivation, specific objective
Since it can measure luminous intensity distribution, luminous flux, luminous efficiency andother important performance parameters of lamps and luminaires, the goniophotometer(goniophotometry) is more and more widely used in the design and development, quality
testing and application of lighting products. In goniophotometry, the distance from device
under test (DUT) to electric measuring instrument and power supply is often very long, up totens of meters. Moreover, the electrical performance parameters of DUT may involve highfrequency voltage, high-frequency current and high-frequency power consumption. Therefore,
in order to ensure a lower measurement uncertainty, the cable impedance in goniophotometry
can’t be ignored.
2. Methods
At present, the more commonly used method of increasing the diameter of the wire or using
the four-wire method may not meet the measurement requirements of the goniophotometry,but so far, there is no specific information about the cable impedance of the goniophotometry
with specific data that can be referred to. In this full paper, through the electrical simulation
calculation and analysis of the impedance characteristics of cables in the goniophotometry,the data of the typical cable types in the low-frequency and high-frequency circuits are
obtained. Furthermore, the guides for the selection of cables in the goniophotometry arerecommended based on practical experiments.
3. Results
In DC and low frequency circuits, the impedance of cables is almost purely resistive. Whenfrequency in the circuits is high, the inductive impedance of cables is significant and may leadto considerable measurement errors. Practical experiments show that the impedance ofcables in goniophotometry can be dramatically reduced by using appropriate solutions.
4. Conclusions
Accurate evaluation for impedance of cables in goniophotometry to select the appropriate
cables is indispensable in the design and measurement uncertainty evaluation ofgoniophotometry, and the appropriate solutions should be selected to reduce the impedanceof cables for the goniophotometry.

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PO17
ILLUMINANCE DISTRIBUTION MEASUREMENT OF MUSEUM EXHIBITSUSING DIGITAL IMAGING LUMINANCE METER
Bartsev Alexey, Bartseva Alexandra
All-Russian Scientific Research Lighting Institute named after S.I. Vavilov, RUSSIA
bartsev@vnisi.ru
Introduction
Lighting of museum exhibits should provide an adequate visual perception of the exhibits andat the same time have a minimal negative influence on the safety of these exhibits. To
minimize the degradation of museum exhibits under the lighting usually standardize theminimum possible level of illumination, which still allow museum visitors to perceive
adequately the exhibits [1]. In case of painting, it is important to limit the maximum
illumination in the field of illumination of the picture, because the increased aging of eve n asmall area of the picture limits the permissible exposure of the entire canvas. Therefore, whenmeasuring the light levels of museum exhibits, in particular, paintings, it is very important todetermine the zones and levels of local “overlighting”. In order to do this, it is necessary tomeasure the illuminance at as many points as possible, which is quite difficult and does notalways guarantee that a "dangerous" area will not be missed. Because of this it is quite anurgent task to use measurement instruments and methods that allow us to simultaneously
obtain the distribution of illumination over the entire illuminated area of the museum exhibit.
The appearance of new measuring devices - digital imaging luminance meters ILMD (Imaging
Luminance Measurement Devices) [2], allows us to solve this problem and get a picture of theobject's luminance distribution.
Methodology
The image generated by the ILMD is a luminance image, each element (pixel) of which
determines the luminance value, which characterizes the intensity of the light reflected by theobject in the direction of the observer (human eye or ILMD). However, to assess the quality oflighting of a museum exhibit, you need to know not the luminance distribution, but the
distribution of illumination over the surface of the museum exhibit. Therefore, for the transition
from the brightness image to the distribution of illumination in the plane of the illuminatedexhibit, it is necessary to establish a relationship between the parameters of the reflected lightand the light incident on the object of study.
In general, the solution of this problem is not trivial, but it can be significantly simplified. To dothis, it is enough to place a flat surface (hereinafter referred to as a screen) with knownreflection characteristics in front of the measured exhibit (a painting). The simplest
relationship between the luminance level L i of the screen at the i th point and its illumination

Ei is in the case of the diffuse reflection:
Ei=Li π/ρi ,(1)

where ρ i is the diffuse reflection coefficient at the i th point of the screen.
In this case, it is quite easy to pass from the luminance image obtained with an ILMD to theillumination distribution – it is enough to multiply the luminance value L i of each pixel of theimage by the proportionality coefficient k=π/ρ i , which is included in the formula (1). Thistask solved easily by using the appropriate software.
From practical reasons it is better to use the screen with a known diffuse reflection coefficientρ i . If the ρ i of the screen is unknown, it can be measured in a specialized laboratory using
appropriate measuring equipment. If the diffuse reflection coefficient ρ i of the screen is198

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simular (within the measurement accuracy) for all points of the screen, then the formula (1)will simplifiers more: you can use the average ρ for all points of the screen. In this case, thetask of switching from screen luminance distribution to illumination distribution is even easier.
Results- The method for measuring the distribution of illuminance of museum exhibits in the v erticalplane using digital imaging luminance meters (ILMD) was developed.
- The measurements accuracy was evaluated. The measurement errors were carried out inaccordance with [3] for direct multiple measurements and in accordance with [4] for indirect
measurements. According to this method, permissible relative uncertainty limits for the
average illuminance measurements in the vertical plane are not higher than ± 10,2 %.
- A control experiment was conducted to compare the results of measurements using a h ighprecision luxmeter at 5 control points. The largest discrepancy was 2 %, and the average
difference (across all control points) was ~1 %.
Conclusion
In general, the method of illuminance distribution measuring by using ILMD and diffuse screen
in front of the painting picture has a big importance, since it allows getting the detailed
distribution of illuminance in a set of points throughout the canvas. Such measurements willallow the most accurate adjustment of the lighting fittings of local lighting. I n addition, it allows
detecting the local “overlighting” on the canvas and preventing premature aging of thepainting.

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PO18
METROLOGICAL CHALLENGES IN MONITORING OF SKY LUMINANCE DURING DAY
AND NIGHT BY USING LUMINANCE METERS AND RGB IMAGING SENSORS
1

Bouroussis, C.1, Ledig, J.2
National Technical University of Athens, Athens, GREECE, 2 Physikalisch-Technische
Bundesanstalt, Braunschweig, GERMANY
costisb@mail.ntua.gr

Abstract
1. Motivation, specific objective
The luminance of the sky varies dramatically spatially and during day and night. The study on
the variation of sky luminance serves mainly research fields such as daylight studies and themonitoring of light pollution. The luminance of the sky can vary in magnitudes between day
and night while its relative spectral radiance distribution alters by time and by weather (e.g.,clouds, fog, dust, etc.) too. Therefore, measuring and monitoring of the absolute or relative
sky luminance is a complicated and challenging task.
In the recent years, imaging sensors were introduced in many measurement applications andin metrology in general. Imaging devices based on a microelectronic pixel matrix sensor as a
key enabling technology are powerful tools. By combining successive measurements of ascene obtained with different integration times, each pixel can cover an extremely huge
dynamic range when it is needed. Since these sensors are two dimensional, they can, in
combination with wide angle lenses, cover a large field of view of e.g., 2pi which is ideal forsky measurement and monitoring. Therefore, imaging devices are widely used in applications
where a big part or the whole sky dome should be captured. In most cases, the selected
device type is a commercial RGB photography camera equipped with fisheye lens or a si milar
product. These devices suffer from a severe spectral mismatch compared to the nominal
photopic response and their calibration to luminance and traceability to SI is alsoquestionable. In the contrary, luminance measurement devices (photometric spot - andimaging instruments, ILMDs) are rarely used for such application due to their higher cost or
their limited portability.
The objective of this study was to investigate the sources of uncertainty and estimate theirlevel while comparing an instrument dedicated for photometric luminance measurement (i.e.,
spot luminance meter) with an RGB camera in the task of measuring the variation of sky’s
luminance under various conditions. The main target is to demonstrate that the extreme
variation of the sky in terms of luminance and relative spectral power distribution can lead to
noticeable measurement errors when using an RGB camera and under which conditions theseerrors and thus uncertainties of the measurement are significantly increasing.
This study is motivated also by the ongoing work of the TC 2-86 “Glare Measurement by
Imaging Luminance Measurement Device (ILMD)” and a new TC of Division 2 on themeasurement of obtrusive light and sky glow. Both TCs are dealing with measurement
aspects where RGB imaging sensors are widely used by stakeholders. It is therefore of highinterest to investigate potential issues in the current measurement practises and to propose
solutions and possible mitigations.
2. Methods
This study comprises a side-by-side comparison of two types of instruments, a single reflex
spot luminance meter and an imaging system equipped with an RGB filtered CCD sensor.
Both instruments were set to measure the sky luminance throughout day and night for several
days. They have been mounted in a way to point at a part of the sky, clear from any obstacle,
towards south east direction. The measurement interval was set to 1 minute for both
instruments and the integration time to ‘automatic’. Captured data included, beside atimestamp, the average luminance for the spot meter and the integration time and average

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pixel values for all colour channels in a region of interest of the RGB sensor. A temperatureand humidity sensor were also installed close to the instruments in order to record thevariation of the ambient conditions. This study is further ongoing, and more data are expected
to be collected and presented in the final paper.
3. Results
The collected data varied in the range of 7 decades in luminance, correspondingly 6 decades
in camera integration time, and around 10 degrees in ambient temperature. The preliminary
results of the calculation of the dataset showed that there is a noticeable variation in therelative difference in luminance measurements of the two instruments. The relative difference
varies from few 1 % up to multiple 10 % depending on the sky conditions and the day or night
period. The error and thus main uncertainty contribution regarding the relative measurements
is expected to originate from the spectral mismatch of the RGB sensors wit h respect tovarying spectra from day to twilight, the upward flux from artificial light sources that induce
sky glow and is scattered in the atmosphere and clouds. Additional uncertainty contributions
are believed to be the non-linearity of the charge accumulating sensor in combination with theautomatic selection of the integration time as well as the alignment of the measurement fieldsof the two instruments to another, especially in days with unstable cloudiness introducing
inhomogeneous and rapid changes in luminance. More analysis will follow on the complete
datasets of this study.
4. Conclusions
This study demonstrates the huge dynamic range of sky luminance from daytime to night -timeand the time scale of its transition as well as of temporal fluctua tion due to weather. A
monitoring instrument needs to cover at least the range of twilight and night -time luminancewith a sufficient uncertainty to allow a reliable rating, e.g., of environmental zones or changes
induces by renovation of lighting installations. The comparison indicates dominant limitationsof RGB filtered devices related to spectral mismatch also regarding the relative luminancetransients. This can be significantly reduced by a photometric weighting as implemented i.e.
in photometric imaging luminance measurement devices.

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PO19
UNFILTERED TRAP-BASED PHOTOMETER CALIBRATION
1

Kliment, P1,2., Porrovecchio G1., Smid, M1.
Czech Metrology Institute, Brno, CZECH REPUBLIC, 2 Slovak University of Technology inBratislava, Bratislava, SLOVAKIA
pkliment@cmi.cz

Abstract
1. Motivation, specific objective
LED-based light sources have currently started massively replacing traditional sources both inarea of general lighting applications as well as in the broader scope of optical technologies
utilizing the optical radiation outside the visible spectrum range. The advanced metrology
traceability chains realized in leading NMIs in Europe utilize the absolutely calibrated
broadband radiometers (three-element silicon trap detectors) for calibrating prima ry
photometers. Specific spectral properties of LED and OLED-based light sources allow toapply the broadband standard radiometers directly as new primary photometers. They are
equipped by a precise optical aperture at the entrance. In contrast with standa rd V()-filteredphotometers they don’t use any problematic long-term instable optical filters. The photometricweighting is done numerically and they need to be calibrated for the spectral irradianceresponsivity in the spectral range corresponding with the spectral power distribution of themeasured LED sources.
CMI has a long experience in high precision detector-based spectral irradiance responsivity
calibrations declared by particular CMC’s published in KCDB database of MRA. The aim of
this work was to revise the uncertainty budget in order to reduce the measurement
uncertainties for specific application of calibration of unfiltered primary photometers. The two
calibration methods were used to analyse the occasional back -reflection effect of the trapbased unfiltered photometer (DUT) front aperture. The measurement was performed using
CMI reference spectral responsivity facility in spectral range 350 nm – 900 nm.
2. Methods
The three-element silicon trap detector traditionally used in the radiometry as a transfer
standard for an absolute spectral responsivity scale, was applied as a base of the trap -based
unfiltered photometer (DUT). The detector was adopted to measure the irradiance which isneeded to calculate the illuminance and luminous intensity. T he precision optical aperture
with a diameter of 3 mm was designed, produced and mounted on the front of the detector
entrance. The spectral responsivity homogeneity of the DUT was characterized andaccounted for the uncertainty budget.
The DUT calibration of the absolute spectral irradiance responsivity was performed using CMI
primary monochromator-based facility. The core of the facility is formed by double grating
monochromator with subtractive dispersion, focal length 350 mm. One couple of ruled
gratings 600 G/mm, blazed at 550 nm is used for dispersing the beam in the spectral range
350 nm – 900 nm. Whole system was developed and characterized at CMI such that itreaches wavelength uncertainty 0.1 nm over the whole spectral range of interest, output be am
uniformity 0.1% over the area of interest and the optical throughput not smaller than 10 W
for spectral bandwidth 4 nm FWHM. The CMI reference transfer standard trap detector has adirect traceability to the CMI primary absolute cryogenic radiometer with the uncertainty well
below 0.1% over the whole spectral range of interest. A custom -made knife-edge profiled
calibrated optical aperture was designed, produced and assembled in front of the traps
detector optical input aperture to define the reference plain of unfiltered photometer as well as
the area of the optical input. Calibration of all g eometrical parameters of the optical aperture
was performed using CMI reference 3D coordinate measurement machine achieving theuncertainty of 0.5 m, concluding the uncertainty of the aperture area of 0.007 mm 2 .

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The calibration of the spectral irradiance responsivity of the DUT was performed by two
independent ways to analyse the occasional back-reflection effect of the trap-based unfilteredphotometer (DUT) front aperture. At first the aperture of the DUT was removed and thespectral power responsivity was measured in underfilled configuration with the beam diameter
approximately of 3 mm. The aperture area was independently calibrated and the spect ral
irradiance responsivity was then evaluated assuming an ideal performance of the input
calibrated aperture as the area defining artefact.
The second technique was the direct spectral irradiance responsivity measurement when thefront aperture of the DUT was overfilled by the measuring beam. The DUT (with mounted
aperture) was compared with CMI spectral irradiance measurement. The spectral irradiance inthe reference plane of the DUT was measured using CMI calibration setup, using transfer
standard trap detector and precise calibrated aperture positioned such that all internalreflections were fully under control and their effect to the calibrated quantity was eliminated.
The deviation of the results of both calibration techniques was utilized then as a v alidation of
newly established uncertainty budget.
3. Results
The spectral irradiance responsivity of the trap-based unfiltered photometer was evaluated forboth measurement techniques. The CMI uncertainty budgets were completely revised. The
newly analysed uncertainty sources such as residual errors of the wavelength scale, DUT
spectral responsivity nonuniformity, alignment and others were implemented. As a result, thetotal uncertainties were reduced from 0.50 % to 0.34 % in the spectral range 450 nm –900 nm and even from 1,00% to 0.46% in the spectral range 350 nm – 400 nm.
The deviation of the results given by the two techniques was under the measurement
uncertainty. It confirmed the negligible influence of the back -reflections of the front aperture of
the DUT which was expected during the first measurement technique.
4. Conclusions
Specific spectral properties of LED and OLED-based light sources allow to apply the trapbased unfiltered photometer directly as a new primary photometer. In contrast with s tandard
V()-filtered photometers they don’t use any problematic long-term instable optical filters. The
photometric weighting is done numerically and they need to be calibrated for the spectral
irradiance responsivity in the spectral range corresponding w ith the spectral power
distribution of the measured spectrally limited sources.
The adapted method of calibration of absolute spectral irradiance responsivity wasdemonstrated. The CMI uncertainty budget was completely revised and as a result the total
uncertainties were significantly reduced.
Another calibration technique calculating the spectral irradiance responsivity from thecalibrated spectral power responsivity and calibrated area of the aperture confirmed thenegligible influence of the back-reflections of the front aperture for the CMI specific set-up of
trap-based unfiltered primary photometer.

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PO20
IMPACT OF THE NORMALIZATION OF THE SPECTRAL RESPONSIVITY ON THE
PERFORMANCE OF THE GENERAL V(Λ) MISMATCH INDEX
1

Ferrero, A.1, Thorseth A.2
Instituto de Óptica “Daza de Valdés”, Consejo Superior de Investigaciones Científicas,
Madrid, SPAIN, 2 Technical University of Denmark, Roskilde, DENMARK
alejandro.ferrero@csic.es

Abstract
1. Motivation, specific objective
The photometric performance of photometers is usually evaluated by the general V(λ)
mismatch index, f 1 ’, which considers the mismatch between the spectral responsivity ofphotometers, s(λ), and the spectral luminous efficiency function, V(λ). In order to compare thisspectral mismatch, the spectral responsivity needs to be scaled by us ing a normalization
factor. The present normalization factor is a function which includes explicitly the relative s(λ),V(λ) and the CIE Standard Illuminant A spectral distribution, S A (λ). This factor normalizes s(λ)
to have a luminous responsivity of 1/K m when calibrated with respect to S A . Nowadays, mostof the evaluated light sources are based on LEDs, and it is expected that the CIE Standard
Illuminant A will be replaced by an LED-type illuminant as reference spectrum (CIE TC 2-90).
It has raised interest in defining a complementary index for this upcoming scenario, better
suited for assessment of LED-based light source. To define this complementary index, thenormalization in the present quality index can be simply modified, or a new different approach
can be used. In this work, the former option is examined.
We think that the type of explicit normalization defined for f 1 ’ (expressed here as f 0 ’ when thedefined normalization is replaced) is not the most adequate to scale s(λ) and V(λ) to assess
their spectral dissimilarity. We hypothesize that a higher correlation with the expected mean
photometric error would be obtained if an optimal normalization factor, found by numerical
optimization, is applied. The reasoning behind this is that the normalization factor reaching
the minimum value of f 0 ’ provides the better overlapping of s(λ) and V(λ), and that any othernormalization factor would include a normalization-related dissimilarity component. The
objective of this study is to show the impact on f 0 ’ when different explicit normalization factors
are used, and the improvement when using an optimal normalization factor.
2. Methods
Different normalization options were evaluated, and their suitability was quantified with thelinear correlation coefficients between the obtained f 0 ’ indexes and the expected mean
photometric errors. 77 spectral responsivities of real photometers and spectral distributions
from CIE recommended illuminants were used to estimate ground -truth values of the mean
photometric errors from the spectral mismatch correction factors (SMCFs). The optimal
normalization factor was calculated by a numerical optimization procedure, minimizing thevalue of f 0 ’ for each photometer.
3. Results
In a phosphor-based-LED scenario (meaning here that the SMCFs are calculated using the 9phosphor-based-LED illuminants lately recommended by CIE, with the illuminant with CCT,
T cp , equal to 4100 K as calibration illuminant), the following linear correlation coefficients,  ,between indexes and mean photometric errors were found to be:

0.801 for f 1 ’;

0.815 for a f 0 ’ with the LED illuminant with T cp = 4100 K is used in the normalization;



0.784 for a f 0 ’ with the equal energy illuminant;

0.844 for a f 0 ’ with the optimal normalization factor.

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Similar coefficients were obtained when using the different phosphor -based LED illuminants
for calculating the modified f 0 ’, with values ranging between 0.816 (T cp = 4100 K) and 0.832(5700 K). Similar coefficients were also obtained when using all phosphor -based LED
illuminants for estimating a more general mean photometric error, by combining them a s
reference and evaluated light sources in the calculation of SMCF, with around 0.7 % smaller
values for all coefficients  .
In a blackbody scenario (meaning here that the SMCFs are calculated with 9 blackbody
illuminants at the same colour temperature as the CCTs in the phosphor-based-LEDs
scenario, with the Standard Illuminant A as calibration illuminant), the following linear
correlation coefficients between indexes and mean photometric errors were found to be:

0.760 for f 1 ’;

0.784 for a f 0 ’ with the LED illuminant with T cp = 4100 K;



0.763 for a f 0 ’ with the equal energy illuminant;

0.815 for a f 0 ’ with the optimal normalization factor.

Similar coefficients to that of f 1 ’ were obtained when using different blackbody illuminants forcalculating f 0 ’, with values ranging between 0.753 (for T cp = 3500 K) and 0.777 (for T cp =6500 K).
4. Conclusions
This study suggests that the normalization based on the CIE Standard Illuminant A defined forf 1 ’ is not the most optimal for any of the examined scenarios. It provides a similar estimate of
the general photometric performance of photometers when using the equal energy illuminant.
This is worse than if, instead, a phosphor-based LED is used for the normalization, not only
under a phosphor-based-LED scenario, but also under a blackbody scenario.
The normalization with the phosphor-based LED of T cp = 5700 K provides the quality index
with better correlation with respect to the mean photometric error, although there is no
significant difference with respect to the other LEDs.
We can conclude that the most suitable normalization in the definition of a f 1 ’-type quality
index is not determined by the spectral distribution used in the calibration or by the those of
the light sources to be measured. In addition, the optimal normalization factor, obtained byminimizing the index and not by a function as in f 1 ’, shows the best correlation in the studied
cases, as hypothesized. However, it is not clear that the improvement of using an optimal
normalization in the definition of the index justifies the revision of the present CIE
recommendations. We suggest using a similar methodology to examine the suitability ofindexes defined by alternative approaches.
Acknowledgement
This project 19NRM02 RevStdLED has received funding fro m the EMPIR programme cofinanced by the Participating States and from the European Union’s Horizon 2020 researchand innovation programme.

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PO21
HANDLING OF CORRELATIONS OF SPECTRAL QUANTITIES IN TRACEABILITY CHAIN– BASICS FOR A PYTHON-BASED ANALYSIS FRAMEWORK
1

Schneider, Philipp1, Sperling, Armin.1
Physikalisch-Technische Bundesanstalt, Braunschweig, GERMANY
philipp.schneider@ptb.de

Abstract
1. Motivation, specific objective
When calculating integral radiometric or photometric quantities, like photomet ric responsivities
or colour coordinates, correlations of the spectral data can greatly influence the resulting
measurement uncertainty. On one hand, correlations can be utilized to reduce themeasurement uncertainty when the measurement is set up accordin gly. On the other hand,
spectral correlations can cause higher uncertainty when calculating integral quantities orinterpolating between measurement data points. National Metrology Institutes (NMIs) should
therefore be obliged to include correlations within their traceability chains in the uncertainty
analysis and, if possible, should provide correlation or covariance matrices together with
disseminated spectral quantity values within their calibration services. Within the European
research project 19NMR02 “Revision and extension of standards for test methods for LED
lamps, luminaires and modules” (RevStdLED) one objective is for the NMIs to develop
guidelines for estimation of uncertainty of integral quantities from spectral quantities for test
laboratories. Within these objectives it is up to the participating partners to determine thecorrelations for the quantities of spectral irradiance and spectral irradiance responsivity. To
establish the handling of correlations not only at NMIs but also in testing an d calibrationlaboratories a supportive software framework is suggested in this contribution in addition to
the planned guidelines of RevStdLED.
2. Methods
Using Monte Carlo methods is an easily accessible way to estimate measurement
uncertainties, as only the measurement equation is needed. A prerequisite for such an
uncertainty analysis is a method to at least generate uniformly distributed numbers between 0
and 1 or readymade tools to generate random numbers according to given distributions. A
convenient tool for doing Monte Carlo calculations is provided by Python programming
language, as it is both versatile and free to use. Freely available Python modules like “numpy”
and “scipy” provide many useful functions for scientific purpose and allow to quickly draw
random numbers for the Monte Carlo simulations of the measurement equation.
3. Results
As a supportive framework a set of Python methods will be presented together with code
examples. It includes functions for Monte Carlo simulation of uncorrelated values of a given
input quantity or based on measurement results as well as of correlated values based oncorrelation or covariance matrices and a set of input quantities. Additionally, a method forevaluating the results for the output quantity of the Mon te Carlo calculation will be presented.
The use of these functions will be demonstrated based on a few specific examples ofmeasurement uncertainty analysis along traceability chain for spectral irradiance andphotometric responsivities at PTB.
4. Conclusions
Providing a free-to-use framework of Phyton routines for uncertainty calculations including
correlations can support establishing a general treatment of correlations in photometry, e.g. incalibration laboratories and industry. For this purpose, a set of functions is provided that canlower the threshold of treating correlations in the uncertainty analysis. Together with theguidelines in development in the RevStdLED project this framework can work towards regularcalibration of photometric quantities based on spectral measurements taking correlations into

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account as required by the guide to the uncertainty in measurement. This project 19NRM02
RevStdLED has received funding from the EMPIR programme co -financed by the Participating
States and from the European Union’s Horizon 2020 research and innovation programme.

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PO22
EXPERIMENTAL VALIDATION OF THE 200 NM LIMIT FOR MEASUREMENTS OFULTRAVIOLET RADIATION IN AIR
1Bergen, A.S.J.1
Photometric Solutions International, Melbourne, AUSTRALIA
tonyb@photometricsolutions.com

Abstract
1. Motivation, specific objective
The region in the ultraviolet (UV) optical radiation spectrum below 200 nm is referred to as“Vacuum UV” (VUV). There is a principle that measurements in that wavelength region shouldbe performed in a vacuum or in a nitrogen atmosphere otherwise the oxygen and ozone
present in the air will absorb some of the radiation and will invalidate the measurements. But
this general rule of thumb leads to questions: Is 200 nm just a conveniently rounded number?
 Is the 200 nm limit a hard limit?
 Do some effects of absorption start even above 200 nm?
 How significant is the absorption as we move to wavelengths below 200 nm?
While there are references explaining how absorption of optical radiation by oxygen andozone can be calculated from first principles, this requires measurement of the amount ofoxygen and ozone in the air, and traceability is questionable. Determination of the absorptionof the UV radiation by experimental means is therefore desirable.
2. Methods
An experiment was set up where a laser drivel light source (LDLS) was positioned directly infront of the entrance slit of a double monochromator. The LDLS emits radiation from a plasma
inside a very small bulb – the source is therefore very small (of the order of a few millimetres)
and has a very high radiance. The entrance slit of the double monochromator is less than 3
mm wide for a 5 nm bandwidth. The conditions are therefore such that when the test distanceis 200 mm or greater, the inverse square law will be valid.
The LDLS was positioned initially such that the test distance was approximately 200 mm. The
relative spectral irradiance distribution was measured over the wavelength range 180 nm to
400 nm in steps of 5 nm. The LDLS was then moved backwards away from the entrance slit insteps of 50 mm out to 700 mm, with the spectrum being measured at each position. This was
repeated several times in order to average the data and reduce noise.
For wavelengths of 250 nm to 400 nm, it is assumed that there is negligible atmosphericabsorption (they are well above the VUV limit). The measurements at each of thesewavelengths can therefore be used to determine the offset in the assumed test distance using
the inverse square law as follows: For each wavelength, calculate the relative spectral radiant intensity at each distance plus
a distance offset which is given an arbitrary starting value.
 Calculate the standard deviation of the relative spectral radiant intensity values.
 Adjust the distance offset to minimize the standard deviation using an iterative approach(e.g. Excel solver).
 Repeat for all wavelengths and calculate the average distance offset.

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This offset can then be fed back into the data to calculate the relative spectral radiantintensity from the relative spectral irradiance data for all wavelengths. If the inverse square
law holds then the relative spectral radiant intensity calculated at each distance should beconstant. For the wavelengths in the VUV region, therefore, any variations from the inverse
square law could reasonably be attributed to absorption of the radiation by the air.
Because the sets of measurements are calculated independently at each wavelength, theabsolute spectral irradiance is not needed, i.e. the relative spectral irradiance da ta can beused and hence an absolute radiometric calibration is not required.
The LDLS was not nitrogen-purged, as this may interfere with the oxygen content of the air inthe vicinity of the experiment.
3. Results
For all wavelengths of 200 nm and above, the relative spectral radiant intensity calculated
from the relative spectral irradiance using the inverse square law with the corrected test
distance was constant to within 2 %. This indicates that there was negligible atmosphericabsorption at these wavelengths.
At 195 nm, the data indicated a deviation in the calculated relative spectral irradiance ofapproximately 3 % over the distance of 500 mm travelled.
At 190 nm, the deviation was approximately 15 % over the distance of 500 mm travelled.
At 185 nm, the deviation was approximately 35 % over the distance of 500 mm travelled.
At 180 nm, the data was too noisy to calculate the effect.
As this experiment so far was a proof of concept, no attempt at evaluation of measurement
uncertainty has as-yet been undertaken.
The measurements to date have been using a UV-enhanced silicone photodiode with thephotocurrent fed into a transimpedance amplifier and measured. As the responsivity of thesilicone decreases markedly with reduced wavelength it is not surprising that the data
becomes increasingly noisy at the lower wavelengths.
Work is currently ongoing to: Repeat the experiment using a photomultiplier tube to improve the signal;
 Repeat the experiment more times to determine the repeatability of the setup; Use a reduced bandwidth and wavelength interval of 1 nm in order to provide more data; Evaluate measurement uncertainties.
This work is expected to be completed by June 2021.
If the ongoing work provides reliable data at a reduced wavelength interval, then it may bepossible to determine a mathematical model that can be used to correct data measured atwavelengths lower than 200 nm. However, this will require measurement of the amount ofoxygen and ozone in the air, and it is not presently clear whether this will be achievable or not.
4. Conclusions
The absorption of ultraviolet radiation over a 500 mm distance for wavelengths of 200 nm andgreater is less than 2 %. For most measurement applications this can be considered to be
negligible.
At wavelengths of 195 nm and lower the absorption of ultraviolet radiation becomes significant.
The 200 nm lower limit for measurement of UV radiation in air has been experimentally
validated.
Work is ongoing to refine the results and evaluate measurement uncertainties.

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PO23
THE CORRELATED COLOUR TEMPERATURE:
AN INFLUENTIAL PARAMETER IN AGEING OLEDSBen Abdellah, O.1, 2, El Halaoui, M.1, 2, Al Haddad, A.1, Dupuis,P.1, 3, Canale, L1, Asselman, A2, Zissis, G 1
1
LAPLACE UMR 5213 CNRS-INPT-UT3, Université de Toulouse, 118 route de Narbonne,
31062 Toulouse CEDEX 9, FRANCE,
2
Optics and Photonics Laboratory, Université Abdelmalek Essaadi, Tetouan, MOROCCO,
3
Kawantech S.A.S, 6 Rue Françoise d’Eaubonne, 31200 Toulouse, FRANCE,
oussama.benabdellah@laplace.univ-tlse.fr

Abstract
1. Motivation, specific objective
In the last two decades, the LED (Light Emitting Diode) lighting system started to grow andgained ground amongst other lighting technologies (incandescent bulb, fluorescent lamp, andothers) because of its high luminous efficiency and its long life expectancy. Recently, LCA(Life Cycle Assessment) of lighting systems studies pointed out that the ecological footprint of
the LED system is not as competitive as its efficiency or its lifetime. This can be explained by
the amount of rare raw material that are used in order to produce LED chips and the circuitboards required to their alimentation, and by the magnitude of the energy consumption during
the production stage. Additionally, the impact of the end -of-use phase differs from a country
to another depending on their recycling competency. Moreover, the LED lamps are far frombeing totally recycled because of the system complexity. Representing a market size of 54
billion USD in 2019 with an annual growth rate of 13.4 %, the LED lig hting system is heading
to replace all the existing lighting technologies within the next decades. In this case, a highpercentage of LEDs will be landfilled or ignited relying on the recycling capacity of different
regions, bringing the idea to improve the performance of the (Organic Light Emitting Diode)
OLED source and making it a competitor to the LED light source with a higher recycling rate.
In order to understand and ameliorate OLED’s weaknesses, photometric characterization
studies of this later under thermal and electrical stresses were realized and have shown that
the OLED light source is critically impacted with important temperature levels, e.g., thelifespan of an OLED can go from 10000 hours (under normal circumstances), to 2000 hours
under a controlled temperature of 60 °C, i.e., the luminance level decreased by 30% after only
2000 hours instead of 10000 hours when powered at nominal conditions.
This study will provide the lighting community a better understanding of the OLED degradation
by studying OLEDs with different CCTs (Correlated Colour Temperatures) considering that ahigh CCT OLED (i.e. OLEDs that contain a high proportion of blue light compared to the other
SPD (Spectral Power Distribution) parts) could suffer a greater and faster det erioration.
2. Methods
Our team have thoroughly studied and investigated the behavior of warm white OLEDs (3 000K) as a function of time, current density and temperature, and recently published our work oncolorimetric characterizations of stressed OLEDs using IES TM-30-18 colour rendering
method. This study, in which colorimetric parameters such as Rf (fidelity index), Rg (Gamut
Index), CCT and Duv (the distance between the chromaticity coordinate u’ and v' of a lightsource and the planckian locus on the CIE 1976 colour space) were considered, was realized
to understand the colour appearance shifting of warm white OLEDs. In this earlier study, ninestress scenarios were applied, for each temperature level (30 °C, 40 °C and 60 °C), threedifferent electrical current levels were applied (1.22 x I Nominal , 1.41 x I Nominal and 1.63 x I Nominal ).
21 repetitive spectral measurements were done for all the OLEDs with a 10 day period usinga Minolta CS-1000 spectroradiometer till the luminance decline to 70% of the i nitial value.
Slight differences were noticed over time for all the colorimetric quantities. Nevertheless, noevidence were found to promote these variations as noticeably influential regarding users
visual comfort.

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In the actual study, OLEDs are put in thermal enclosure by groups of twelve at a controlledtemperature of 60 °C, the twelve OLEDs are separated into three metallic support, and eachone of these receive a different electrical current density. In total, twenty -four OLED (half witha CCT = 3000 K and the other half with a CCT = 4000K) are being characterized resulting in afour time repeated scenario for every OLED
3. Results
The SPD (Spectral Power Distribution) of all the white OLEDs studied were previously
characterized at different aging moments and it appears that the different OLED light emissive
components does not degrade equally. Precisely, the blue component developed the fastest
degradation and as a result, the blue part ratio decreased from the total SPD. From this result,it can be supposed that high CCT (Correlated Colour Temperature) or Cool White OLEDs’
luminance could be decreasing faster than Warm White OLEDs’ (i.e. OLEDs that contain alow proportion of blue light compared to the other SPD parts) luminance.
4. Conclusions
Current studies of aging OLEDs does not consider the CCT as a degradation factor, hence inthe actual study, twelve warm white (2 900 K) and twelve neutral white (4 000 K) OLEDs are
put in an enclosure under thermal and electrical stress conditions in order to v erify the above
hypothesis and provide a better lifespan predictive model using the temperature, the current
density and the CCT as life time’s influential parameters. In addition, the 99 colour fidelity
indexes of the IES TM-30-18 method of the two different types of OLED will be calculated as afunction of time to understand the impact of the CCT value on the variation of the colorimetricparameters.

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PO24
SIGNAL CHARACTERISTIC OF A CAMERA WITH AN INTEGRATING AMPLIFIER AND
LOGARITHMIC ENCODING AT THE PIXEL LEVEL
1

Ledig, J.1, Klinger, H.1, Schrader, C.1
Physikalisch-Technische Bundesanstalt, Braunschweig, GERMANY
johannes.ledig@ptb.de

Abstract
1. Motivation, specific objective
The measurement of luminance distributions with a high contrast is neede d by many
applications of lighting systems, (daylight) glare rating, obtrusive lighting, and environmental
monitoring, e.g. sky glow. A prominent method is the use of imaging luminance measurement
devices (ILMDs) or RGB-cameras based on an imaging sensor with a microelectronic pixel
matrix as a key enabling technology. In such conventional devices the charge accumulating
mode of the pixel photodiode introduces a saturation and thus nonlinearity; after the
integration time the charge (or a corresponding voltage) is readout by undergoing ananalogue amplification and linear A/D-conversion which typically covers up to four orders ofmagnitude.
A short-circuit pixel photodiode with a charge integrator is a very promising approach and willallow to apply measurement models that are well known from single element photometers, i.e.
spot luminance meters and illuminance meters. Such a principle is implemented in the VIP S2camera prototype of CSEM. This camera contains an HDR image sensor that is based on an
integrating amplifier and a 10 Bit time-domain logarithmic encoding at the pixel level. For low
signals the integration time is up to several 10ms. The image sensor is specified to have amatrix of 320 x 240 pixels with a dynamic range of 130 dB.
The objective of this study is to experimentally determine the luminous responsivity
characteristic of the camera pixels. This should enable to judge the potential benefits and tocompare it with image sensors used in conventional ILMDs.
2. Methods
The luminous responsivity characteristic of the VIP S2 camera is characterized by varying theluminance value of an illuminated diffuse reflection target over six orders of magnitude, from
10 mcd/m² to 10 kcd/m². These different illuminance levels are realized by changing the
distance of a light source based on a white LED from about 0.2 to 10 m and therefore
implicitly maintaining the relative spectral power distribution and by two different
configurations of a concentrating lens in front of the illuminating source. Higher lumina nce
levels up to about 20 Mcd/m² are represented by the light source itself and in combination
with neutral density filters. The luminance level is monitored by a photometer (spot luminancemeter). This monitoring photometer is based on a transimpedance am plifier that maintains a
short circuit condition of the filtered photodiode and therefore is a reference with neglectablenonlinearity.
The absolute luminous responsivity of the monitoring photometer and the camera are affectedby their spectral mismatch, which is huge for the camera. But for each luminance with thesame relative spectral power distribution their ratio is constant and thereby the relative
variation with luminance serve as a measure for the signal characteristic of the camera.
3. Results
The pixel signal presents a logarithmic characteristic for luminance levels of five decades up
to 130 kcd/m² and a more linear characteristic for about 400 mcd/m² up to a few cd/m². The
largest signal is observed at about 1 Mcd/m² (corresponding to a signal l evel of 970 counts),
while for higher luminance levels a negative slope of the signal characteristic versus
luminance is observed. For the investigate luminance levels of up to 20 Mcd/m² a unique

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assignment of the signal is therefore possible only below a luminance of about 30 kcd/m²(corresponding to a signal level of 780 counts) which results in a usable measurement rangeof less than five decades.
At high pixel illuminances the signal characteristic obviously changes, which is attributed to alimited current capability of the analogue frontend inside the pixel rather than to a reset phasetiming issue. From a published schematic of the pixel circuit it is assumed that the reset
phase might be affected by high illuminances, which results in an altered bias voltage at the
pixel diode and thus a reduced photocurrent compared to that at a lower illuminance. D uring
the integration phase this photodiode bias is maintained by the common-source amplifier andcorrespondingly the device signal characteristic presents a negative slope.
4. Conclusions
The relative luminous responsivity characteristic of the investigated camera represents apromising principle but deviates from the intended signal characteristic. Regarding
microelectronic pixel sensors this demonstrates that the equivalence of findings fromsimulations of the analogue frontend, or from a functional block diagram, with the signal
characteristic of a real device should be demonstrated by measurements in the entire
dynamic range. Namely covering the upper and lower limits and including a check of thesignal at levels outside the dynamic range.
For the investigated prototype the found dynamic range is three orders of magnitude lower
than specified. The observed upper limit of the dynamic range is ascribed to the design of theanalogue frontend, namely the parameters of individual transistors. This might be adopted ina revised prototype, i.e. by an increased channel width of transistors that are currently limiting
the photocurrent regarding the intended characteristic. The lower limit of the dynamic range iscurrently given by the integration time and end phase configuration, but not yet by a noise
limit. Therefore, an operation at an increased counter period (an increased integration timeand reduced margin to the noise limit) corresponds to a shift of the dynamic range away fromthe high photocurrent regime and is expected to significantly extend the dynamic range tolower illuminances. This is i.e. very interesting regarding monitoring and assessment of sky
glow.
With the present configuration as delivered by the manufacturer namely a high luminanceabove 1 Mcd/m² (as present by a direct view into an LED, incandescent lamp or by the sun in
the field) is not covered by the measurement range. Instead, the signal from such a luminancelevel might be mixed up with that of a lower luminance level. This issue can only be excluded
by boundary conditions or additional measurements, i.e. using a neutral density filter, tocheck whether the signal slope at each pixel level is positive or negative.

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PO25
RevStdLED: A EUROPEAN PROJECT TO SUPPORT THE REVISION OF STANDARDSRELATED TO SOLID STATE LIGHTING
Sperling, Armin, Janne Askola, Jimmy Dubard, Zühal Alpaslan Kösemen, Joaquin Campos Acosta,
Olivier Pellegrino, Anders Thorset, Klaus Trampert, Mykola Huriev, Teresa Molina-Jiménez, Steffen
Görlich, Pieter du Toit, Udo Krüger
armin.sperling@ptb.de

Abstract
1. Motivation
Internationally recognized test methods for lighting products from standardizing bodies are ofsuperior importance for manufacturers to show reliable product performance. Although LED based products show a different behaviour from the metrological point of view with respect toclassical broad-band sources used for light and lighting, the metrological basis for t est
standards did not change. Many CIE, CEN, ISO and IEC Standards dealing with metrology forlighting are based on classical photometry based instruments optimized to measure lightaccording to Illuminant A, using single element Detectors and do not take into accountfeatures arising e.g. from LED spectra to be measured and modern measurement devices like
spectroradiometers and imaging luminance measurement devices (ILMDs) more frequently
used for measurement.
This circumstance was already highlighted in the research strategy of CIE in 2016. To support
standardization and provide the missing links in metrology, the European EMPIR project
19NRM02 "Revision and extension of standards for test methods for LED lamps, luminaires
and modules" (RevStdLED) was established in 2020.
2. Objectives
Calibration of ILMDs at Test Laboratories:
In the field of near-field goniophotometry, validation of street lighting and glare measurements,
ILMDs play an important role today. However, technology and firmware of ILMDs to ext ract
traceable photometric data from the whole scene with the level of confidence needed is agreat challenge not yet attainable. Rather than establishing a sophisticated generic procedure
for calibration that would overwhelm most calibration and testing l aboratories, RevStdLED will
specify calibration methods for dedicated applications and write guidelines for their use andfor the determination and handling of uncertainty so that test laboratories can implement
testing strategies by their own.
Spectral Correlations:
Today, a typical calibration certificate for a detector used for spectral measurements does nottake into account correlations. Each individual measured wavelength value is treated as
independent of its neighbouring values, although there are c lear dependencies. Depending on
the application, this may result in a severe impact on the measured photometric quantity,
when it comes to an integration of spectral values according to V (  ) or the other colour
matching functions. Based on the investigation of the different abilities of the project partners
and collaborators (NMIs and test laboratories), RevStdLED will work out guidelines forcalibration laboratories as well as for test laboratories regarding how to deal with correlationsin spectral measurements and how to propagate and use correlation in their daily work to
improve confidence and reliability.
Quality Indices:
Currently, standards such as CIE ISO 19476 for characterizing m easuring devices still use
illuminant A as the basis for the assessment, although there is evidence that a device that is214

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mainly used for LED measurements is not necessarily well characterized on this basis. Basedon investigations carried out in the former EMPIR Project “PhotoLED” and in the CIE technicalcommittee TC 2-90, RevStdLED will investigate a new approach for supplementary quality
indices and on this basis provide input for future revisions of CIE ISO 19476 and CIE S 025.
Spatial Distributions:With the increasing market coverage of LED-based light sources, the determination of thespatial distribution of light is becoming more and more important, as it is becoming the main
factor for manufacturers and users in the various applications. RevStdLED will develop a
harmonized metric to describe the geometric characteristics of light intensity distributions andthe measurement uncertainty of such spatial distributed photometric values.
3. Conclusion
This presentation gives an insight into the European EMPIR project 19NRM02 "RevStdLED"
as a whole and shows the current status achieved in technical the work packages and work
plans on traceability of ILMDs, correlations of spectral measurements and improvements ofthe standards ISO 19476 and CIE S 025 / EN 13032-4. This project 19NRM02 RevStdLED
has received funding from the EMPIR programme co-financed by the Participating States andfrom the European Union’s Horizon 2020 research and innovation programme.

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PO26
MEASUREMENT OF NORMAL / HEMISPHERICAL REFLECTANCE BY
GONIOSPECTOPHOTOMETRY
Tejedor-Sierra, N, Ferrero, A, Campos, J
Consejo Superior de Investigaciones Científicas, Madrid, SPAIN
nestor.t@csic.es

Abstract
1. Motivation, specific objective
Normal / hemispherical (0º:d) reflectance is the ratio between th e total reflected radiant flux
and the normally incident radiant flux. The measurement of the 0º:d reflectance is usuallyaccomplished by integrating-sphere-based methods. An alternative method based on goniospectrophotometric measurements is described here. By measuring the Bidirectional
Reflectance Distribution Function (BRDF) at specially selected bidirectional geometries, the0º:d reflectance is obtained by Riemann integration. The BRDF measurement provides, inaddition, a more thorough insight into the reflectance of the samples. This work is part of aninternational comparison on the measurement of the 0º:d reflectance.
2. Methods
The gonio-spectrophotometer used for the measurement of the 0º:d reflectance consists ofthree subsystems:
13) The irradiation subsystem. It is a Xenon Lamp, with a Köhler optical system to evenly
irradiate the samples and a monochromator which provides spectral resolution.
14) The sample-positioning system. It is a six-axis robot-arm.
15) The detection system. It is a photodiode on a moveable platform on a ring, allowing thephotodiode to rotate around the sample keeping a constant distance.
The freedom degrees of the robot-arm and the moveable platform allow the realization of any
pair of irradiation and collection directions (bidirec tional geometries).
Four samples were evaluated, two ceramics with a mate finish and two of sinteredpolytetrafluoroethylene (PTFE). 0º:d reflectance was obtained by measuring their BRDF at a
fixed incidence angle (0º) and eleven collection angles (5º, 13º , 21º, 29º, 37º, 45º, 53º, 61º,
69º, 77º and 85º), applying then Riemann integration. The selection of the collection was
based on previous numerical simulations, and it is a trade -off between simplicity and accuracy.
The anisotropy of the samples was previously assessed in the gonio-spectrophotometer andaccounted for in the uncertainty budget. Measurements were carried out at thirteen
wavelengths (360 nm, 380 nm, 400 nm, 420 nm, 440 nm, 480 nm, 530 nm, 580 nm, 630 nm,
680 nm, 730 nm, 780 nm, and 830 nm).
The BRDF of a given sample is obtained from a relative BRDF measurement referred to thegeometry 0º:45º for which the radiance factor of reference standards of the laboratory has
been determined. The comparison between those data is possible because we hav e the samemeasurement conditions regarding solid angle (keeping constant the distance sample detector).
3. Results
Values and uncertainty budget for each studied sample will be reported in this communication.
Their relative standard uncertainty is lower than 0.4 % at wavelengths under 750 nm. For
longer wavelengths uncertainty is less spectrally uniform, but always below 0,8 %. The main
component of uncertainty is due to the radiance factor scale realized in our laboratory.

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0º:d reflectance values have been compared with those obtained with an integrating sphere
instrument. Comparison results will be presented.
4. Conclusions
The 0º:d reflectance of four samples with high diffuse reflectance has been calculated as anintegrated value from their BRDF measurements done with a gonio-spectrophotometer. The
relative standard uncertainty of the measurement is generally below 0.4 % and limited by theuncertainty of the value of the 0º:45º reflectance factor standard. The methodology and theresults of the measurement presented will be thoroughly discussed.
Acknowledgments
This work has been done within the EMPIR 18SIB03 project “New quantities for themeasurement of appearance” (BxDiff). The EMPIR is jointly funded by the EMPIR
participating countries within EURAMET and the European Union. The authors are grateful tothe project PGC2018-096470-BI00 BISCAT (MCIU/AEI/FEDER, UE).

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PO27
UNCERTAINTY OF THE SPECTRAL MISMATCH ERROR IN MEASUREMENTS OF
WHITE LEDS WHEN REFERENCING THE LUMINOUS RESPONSIVITY TO AN LED
REFERENCE SPECTRUM L41
1

Ledig, J.1, Schneider, P.1, Kröger, I.1
Physikalisch-Technische Bundesanstalt, Braunschweig, GERMANY
johannes.ledig@ptb.de

Abstract
1. Motivation, specific objective
The technical report draft 7.3 (TR) of TC 2-90 “LED Reference Spectrum for Photometer
Calibration“ includes a recommendation of CIE reference spectrum L41 (an extrapolation of
CIE Illuminant LED-B3 published in CIE 15:2018 to the full photometric wavelength range of360 nm to 830 nm) to complement the Standard Illuminant A to be used for referencing
photometer measurements of white LEDs, i.e. by a corresponding calibration factor. The TR
draft also reports spectral mismatch errors obtainable in measurements of LEDs when using
typical V(λ)-filtered photometers, but an estimation of the related uncertainty contribution is
missing. Both, the mismatch error and its uncertainty, are needed for traceable measurementsof real light sources by V(λ)-filtered photometers and also during the calibration of its
luminous responsivity with respect to L41, as the spectral power distribution of a standard
source will always differ from the nominal reference.
In its Annex B the TR named linear correlations between the spectral distribution mismatch
index f sd,L41 of the measured light source and the mean mismatch error or percentiles of thespectral mismatch error of typical photometers is given with respect to a large set ofphotometers. The Annex gives an estimate for the expected interval of the absolute spectral
mismatch error, but the (typical) uncertainty of spectral responsivity measurements ofphotometers used is not considered at all. Correspondingly, the reported percentiles ofspectral mismatch for a given spectral distribution mismatch index f sd,L41 of the light source
and the V(  ) mismatch index f 1 ’ of the photometer cannot be used as an upper limit of thespectral mismatch of a typical photometer (i.e. as a tolerance interval used in an uncertainty
determination).
2. Methods
For several illuminance meters (photometers), the luminous responsivity is exemplarily
calculated from their spectral responsivity calibrated at an NMI and a set of relative spectral
power distributions, each corresponding to a white LED artefact. In addition, for eachphotometer the spectral mismatch error when referencing the measurement of this LED
spectra to both the CIE reference spectrum L41 and to Standard Illuminant A is calculated.
The uncertainty of the spectral mismatch error is determined by Monte Carlo simulations . The
fully correlated uncertainty component of the absolute spectral responsivity is assumed to becovered inside the uncertainty of an absolute scaling factor, leading to a probably moderately
correlated uncertainty of the relative spectral responsivity. For the demonstration of its impact
we therefore assume that the latter is fully uncorrelated.
The uncorrelated uncertainty component of the relative spectral responsivity is propagated tothe spectral mismatch error by a linear equation that includes th e spectral integral bysensitivity components related to the relative spectral responsivity, the reference spectrum
L41 and the nominal spectral power distribution of the measured light source.
3. Results
As also stated in the TR, the spectral mismatch errors in measurements of typical white LEDs
are reduced by a factor of 2 on average, when referencing the luminous responsivity to CIE

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reference spectrum L41 compared to Standard Illuminant A, and converges to 0 for a perfectmatch to the used reference spectrum. The measurement uncertainty of the spectral
mismatch error is in most cases reduced by a lower factor than the error itself, in some cases
it is even increased, and thus renders in a higher relative measurement uncertainty of theerror. Therefore, the uncertainty contribution from spectral mismatch error increases insignificance.
Regarding the spectral mismatch error the absolute scaling factor of the spectral responsivity
and its uncertainty (i.e. the fully correlated uncertainty component of the re lative spectral
responsivity) cancels out already in the equation, but the uncertainty of the relative spectral
power distribution of the LED measured by the photometer and the uncertainty of the relative
spectral responsivity (and the spectral power distr ibution) needs to be considered.
In addition to these photometers with a dedicated spectral responsivity calibration, we will
demonstrate the impact on the uncertainty of the spectral mismatch error also for specified
estimates of the spectral responsivity (lacking an uncertainty statement) of a set of 120
photometers. To estimate a relative uncertainty of the mismatch error we consider theuncertainty of the relative spectral responsivity that would have been achieved if calibrated at
NMI level, i.e. according to the CMC of an NMI. As an outlook the possible impact when
considering reasonable uncertainties of a spectral responsivity calibration at accredited test
and calibration laboratories will be given.
We also plan to report the uncertainty of the spectral mismatch error for both sets ofphotometers for a large data set of the nominal spectrum from 1495 white LEDs recently
published in a repository when referencing the luminous responsivity to CIE reference
spectrum L41.
4. Conclusions
Regarding the named significant reduction of the spectral mismatch error by using L41 theimportance of the (remaining) uncertainty of the spectral mismatch increases. A reliable
estimate of the not corrected spectral mismatch error as recommended in the TR therefore
needs to include this uncertainty. Already with respect to the uncertainty of spectral
responsivities according to the CMC of NMIs, which subsequently also limits the uncertainty
at test and calibration laboratories, this is important also for high quality phot ometers with avanishing estimate of spectral mismatch error.
Correspondingly also the estimate of the metric f sd,L41 needs to be done with respect to its
uncertainty, i.e. with respect the stability and uncertainty of the relative spectral power
distribution. In calibration laboratories this is much easier than a traceable characterization of
the relative spectral responsivity of the photometer. As already indicated in the TR, thedependence of the spectral mismatch error on the metric f sd,L41 is quite linear and thus is therelated uncertainty propagation. The uncertainty of relative spectral power distribution
measurements significantly depends on the measurement equipment used in the field which isvery diverse and i.e. already covered in separate TCs of CIE D2.

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PO28
GENERIC MODEL FOR GONIOMETER GEOMETRIES
Lerch, D.J.1, Katona, M. 1, Trampert, K.1, Krüger, U.2, Schrader, C.3, Ledig, J.3, Pellegrino, O4,
Neumann, C.1
1
Karlsruhe Institute of Technology, Karlsruhe, GERMANY
2
TechnoTeam Bildverarbeitung GmbH, Illmenau, GERMANY
3
Physikalisch-Technische Bundesanstalt, Braunschweig, GERMANY
4
Instituto Português da Qualidade, Caparica, PORTUGAL
david.lerch@kit.edu

Abstract
1. Motivation, specific objective
In the field of metrology in lighting, uncertainty and comparability are of significant importance.
When measuring a light source with a goniophotometer, there are several sources for
uncertainties, e.g. position and orientation of the measured light source, straylight and thepose (position and orientation) of the measurement device. In the following, the focus is on
the uncertainty of the position and orientation of the measurement device. To evaluate theuncertainty accurate and traceable for all goniometers used, a generic model for thegoniometer geometry is needed. The geometric model of the goniometer is the base for akinematic chain from the measurement device to the measurement object. In robotics there isa standardized procedure to develop the geometric model of a robot. This procedure is here
used to develop the geometric model for goniometers. According to the “Guide to theExpression of Uncertainty in Measurement” (GUM), the geometric uncertainties can beevaluated by Monte-Carlo (MC) simulations. The development of a generic geometric modeland the evaluation of uncertainties by MC simulations is part of the European research project
19NMR02 “Revision and extension of standards for test methods for LED lamps, luminaires
and modules” (RevStdLED).
2. Methods
The generic model for the geometry of a goniometer contains all information about themechanical components of the goniometer such as the size, position and orientation of allcomponents. Moreover, the position and direction of all moving axis are determined andmodelled as joints between two mechanical components. All components of the goniometerare connected by joints to the kinematic chain of the goniometer. The first link of thekinematic chain is the photometer, whereas the measurement object is the last link in the
kinematic chain. This is why the kinematic chain manages modelling of the relationshipbetween measurement and object coordinate system. Mechanical components, in thefollowing named as links and the moving axes, named as joints, of the geometric model aredescribed in Universal Robotic Description Format (URDF), which is an Extensible Mark -up
Language (XML) file format. Thereafter modules of the Robot Operating Software (ROS), a
set of software libraries, are used to create the geometric model. The model developed will be
used to simulate the influence of geometric uncertainties during the measurement. Using thegeometric model for the kinematic chain of a goniometer, uncertainties in linear and angular
positioning can be propagated to the measurement object at the end of the kinem atic chain.
The geometric model allows to simulate uncertainties as a quantity of link -joint-constellations
as well as movement speed of linear and rotational axes. The geometric model and the MC
simulations will be implemented in Python programming langua ge. Both model andsimulations build a framework to evaluate the uncertainties in the geometry of themeasurement setup.
3. Results
The framework consisting of the generic geometric model of the goniometer as well as the MC
simulations for given input quantities and the resulting uncertainties will be presented. Besidethe framework, some results of the MC simulations will be displayed. The generic geometricmodel that will be demonstrated is evaluated on measurement facilities in a laboratory.

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4. Conclusions
As the uncertainty evaluated by the MC simulations will depend on the pose of the goniometer,a geometric uncertainty will be provided for each pose of the goniometer. Moreover, by thisframework, the contribution of all sources of uncertainty to the re sulting uncertainty will becalculated. Therefore, it can be demonstrated that the geometric model offers reliable inputs
to a complete description of geometric correlations. As an additional goal of the RevStdLED
project, guidelines on how to setup such generic model and how to implement it for common
goniophotometers will also be elaborated.
This project 19NRM02 RevStdLED has received funding from the EMPIR programme co financed by the Participating States and from the European Union’s Horizon 2020 resear ch
and innovation programme.

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PO29
STUDY OF METHODS FOR MEASURING THE OPTICAL CHARACTERISTICS OF LOWPRESSURE MERCURY LAMPS.
Zheleznov Igor I.
VNISI Russian Lighting Research Institute named after S.I. Vavilov, RUSSIA
zheleznov@vnisi.ru

Abstract
1. Motivation, specific objective
Obtaining experimental data on the electrical and photometric parameters of low -pressure
tubular amalgam lamps with a discharge in a mixture of mercury vapor and inert gases at highcurrent densities of 0.5-1.2 A/cm 2 with frequencies of tens of kilohertz is one of the key
problems of modern metrology.
Since a full-fledged study of the properties of experimental samples of mercury lamps is
impossible without a reliable method of photometric measurements, and for ozone lamps sucha technique, taking into account the features of the object of study, has not yet been proposed,
its development and testing is the main task of this work.
2. Methods
The paper analyzes the methods for measuring the radiation flux of the 254 nm line, based on
the cosine approximation for the radiation intensity curve (RIC) of the investigated radiation
source (RS), and on the direct measurement of the RIC.
3. Results
Based on the analysis of existing techniques, a tec hnique for measuring the fluxes of the 185
and 254 nm lines of a low-pressure mercury lamp is proposed, taking into account the change
in the nature of the spatial distribution of radiation during operation, without directly
measuring the RIC.
4. Conclusions
The method proposed by the author for measuring the fluxes of ozonizing and bactericidal
radiation can be used as the basis for the development of an automated system for measuring
parameters and monitoring the quality of gas-discharge UV radiation sources.

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PO30
COMPARISON OF LUMINOUS FLUX MAINTENANCE METHODS, CONTINOUS VS.
ON/OFF CYCLES
Corell, D.D., Dam-Hansen, C., Thorseth, A.
DTU Fotonik, 4000 Roskilde, DENMARK
Contact email: ddco@fotonik.dtu.dk

Abstract
1. Motivation, specific objective
The high energy efficacy and long lifetime of LED products provide significant energy savings.
Products don’t always meet their rated lifetime and fail prematurely, negating the expectedenergy savings. In the presented project the lifetime of different LED products will be
investigated, using the new endurance test required by EU in the eco -design regulation from
September 2021. Endurance testing is time consuming so ensuring the most efficient test
method is important. This work will investigate the relationship be tween the test methods
available, to find possible ways of increasing the speed of maintenance testing of LED
products.
2. Methods
A monitoring system has been developed and is currently being used to monitor the
performance on six of the LED products under test. The project is ongoing and will finish in2022.
In this article we will present preliminary data from 16 LED tubes and 30 LED lamps, all of the
products will not have completed the two types of tests. But as much data from the continuous
testing will be presented together with the on/off endurance test.
In the project two methods was used to estimate the lifetime of LED products. The new
endurance test and the IES LM-84 luminous flux maintenance test. The new endurance test
runs for 1200 cycles of 2½ hour on and ½ hour off time, giving a total run time of 3600 hours(or 5 months). The total spectral power distribution of light sources are tested at time = 0 h
and time = 3600 h. The luminous flux maintenance test runs for 6000 hours with the lightsource turned on continuous, and the total spectral power distribution is measured every 1000
hours. In addition to the test at the different time periods for the two methods, the project
have developed a monitoring system that monitors the light output of the light sources
continuously. In case of critical failures, these sensors will help giving a more accurate
estimation of the life time of the products.
3. Results
The LED tubes have been running since the end of December 2020, at this time 16 th of March
the tubes have been running for 2000 hours. Preliminary results shows a slight increase of theluminous flux and small colour shift. More data from the test will be presented in the final
article and at the conference. The LED lamps have been tested at tim e = 0, and plan is tostart the endurance and maintenance test on them in March 2021, preliminary data from thesemeasurements will also be presented in the article.
4. Conclusions
It is too early to come with the final conclusions from the project as the test are still ongoing.
Conclusions will be given for at least one endurance and luminous flux maintenance test on
one product type, and preliminary results will be given for sources still undergoing test, in thearticle and at the conference.

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PO31
CHARACTERIZATION AND ANALYSIS OF SPECTRAL REFLECTANCE OF VARIOUS
INTERIOR MATERIALS DUE TO TUNABLE LED LIGHTING
Zhafirah Ajrinaa), Mangkuto, R.Ab), Revantinoa,c)Engineering Physics Graduate Program, Faculty of Industrial Technology, Institut Teknologi
Bandung, Bandung, INDONESIAb)
Building Physics Research Group, Faculty of Industrial Technology, Institut Teknologi
Bandung, Bandung, INDONESIA
c)
Center for Material and Technical Product, Ministry of Industry of the Republic of Indonesia,
Bandung, INDONESIA
a)b)zhafirah.anis@gmail.com, armanto@tf.itb.ac.id, a,c) revantino@kemenperin.go.ida)Abstract
1. Motivation, specific objective
The current 4.0 industrial revolution, which is correlated with the era of the Internet of Things(IoT), also affects LED-based lighting systems. Wireless networks allow people to beconnected, remotely managing various lighting scenes via tunable LEDs. Meanwhile, theappearance of interior lighting is also determined by the spectral reflectance of the interiormaterial surfaces. With tunable LEDs, it is possible to vary the source CCT; however, it isrelatively unknown whether the change of source CCT shall also vary the spectral reflectanceof materials. Therefore, this study has the following objectives: (1) to identify and analyze thespectral reflectance of various interior material samples due to various CCT from a tunable
LED light source, measured with an integrating sphere, (2) to recommend the mostappropriate CCT value for measuring the spectral reflectance of each colour sample and (3)to determine which colour samples have a robust appearance when illuminated by different
LED spectrums.
2. Methods
The reflectance measurements were conducted using a low-cost, self-assembled integrating
sphere with the diameter of 30 cm. It has 3 ports: the sample port, entrance port (for single
beam source), and the detector port (spectroradiometer). In this study, the 3000K of CCTs
LED spotlight was applied to measure the reflectance of each sample. The diffuse reflectancemeasurement of the material is carried out by placing the sample perpendicular to the lightsource. The spectral reflectance value, ρ(λ) s of the sample can thus be determined from(spectral) irradiance reading on the detector port . The analysis is performed by determining
the prediction of the spectral reflectance appearance by the spectral exitance M e (λ), under the
standard illuminant E and 10 CCT values of Phillips Hue tunable LED lighting (2000-6500 K).
Spectral power density (SPD) of the ten CCT variations were determined by direct
measurement in a dark chamber. Ten colour samples of painted 9mm plywood and ten colo ursamples of wallpapers were introduced and analysed. Moreover, chromaticity difference (inthe form of ∆u'v') was calculated to compare the exitance of each sample under the standard
illuminant E and under the 10 spectra of the tunable LED. In addition, the exitance value ofeach sample was compared with respect to its standard deviation value.
3. Results
From the reflectance measurement, the graph of the spectral reflectance of each sample isobtained from the wavelength range of 420-740 nm. From the exitance analysis, it was foundthat there were 5 colours for both sample groups that had the smallest change of chromaticity
difference (∆u'v') at CCT below 5000 K; i.e. yellow, cream, red, pink, and brown. Moreover,there are 5 colours for both sample groups that had the smallest change at CCT below 5000
K; i.e. dark blue, dark green, light green, gray, and light gray. Moreover, the exita nce value ofeach material under the 10 spectra are grouped in a certain wavelength range, whileobserving the standard deviation. From the standard deviation, it is known that there are224

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colour groups for both materials that have relatively smaller standar d deviations compared tothe other colours; those are dark green, gray, dark blue, brown, and red.
4. Conclusions
Spectral reflectance of painted plywood and wallpaper of yellow, cream, red, pink, brown
colours can be accurately measured under CCT 5000 K of the tunable LED. Meanwhile, dark
blue, dark green, light green, gray, light gray colour samples are best to be measured under
CCT 5500 K of the tunable LED. Darker colour groups (dark gray, dark blue, brown, red anddark green) therefore tend to have a more robust appearance that do not change whenilluminated by any of the ten spectra, compared to the lighter colour groups.

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PO32
CALIBRATION OF SPECTRAL IRRADIANCE SOURCES USING A FIBER-COUPLEDSYSTEM
Brian HT Lee, YC Chau, Brenda HS Lam
Standards and Calibration Laboratory, The Government of the Hong Kong SAR, HONG KONG
brian.lee@itc.gov.hk
1. Motivation, specific objective
Spectral irradiance (unit: mW m -2 nm -1 ) is a fundamental radiometric quantity which refers to
the radiant flux received by a surface with a given area at a specified wavelength. Quartz
tungsten halogen (QTH) lamps mounted in a temperature-stable ceramic socket are widelyused as a reference irradiance light source in calibration laboratories where precise alignment
controls and dark room environment for stray light elimination are required. The light output of
the QTH lamp is coupled to a monochromator through different optics, such as integrating
sphere and parabolic mirrors for radiometric measurements. The effective distance from the
QTH lamp to the measuring system is well defined and normally set at around 500 mm.
In many commercial laboratories, a different type of reference irradiance light source, which isin enclosed form, is commonly adopted due to its simplicity in op eration. A QTH lamp isinstalled in a light housing and light is coupled to its measurement system by using an
adapter or an optical fiber bundle. Normally, the effective distance from the exit split of thelight housing to the measurement system is relative short and within several millimetres. To
support the calibration demands from the industries on this enclosed form of light source, afiber-coupled system using the source-based method is setup in our laboratory.
2. Methods
The calibration is performed with the output of the enclosed irradiance light source coupled toa calibrated fiber-coupled system. The fiber-coupled system consists of a fiber bundle withcosine corrected diffuser (fiber-diffuser hereafter) for the input light-coupling, a double
monochromator with 5 nm bandwidth and a photomultiplier tube (PMT) to convert the opticalsignal to electrical signal. The outer dimension of the cosine corrected diffuser is designed to
fit with the adaptor of the light housing and maintain a fixed separation from the front panel.
The irradiance calibration factor (ICF, unit: mW m -2 nm -1 / A) of the fiber-coupled system isfirst calibrated by comparing with a 1000 W QHT reference standard lamp. The fiber -diffuserof the system and the standard lamp are set at a distance of 500 mm apart. The standard
lamp is powered at its rating current. Stray light effect is eliminated by comparing the light anddark signals through an electronic shutter in front of the fiber -diffuser. With the known spectral
irradiance values of the standard lamp and the corresponding detected electrical signal, theICF of the system can be calculated.
The fiber-diffuser is then plugged into the adapter of the enclosed irradiance light source tomeasure the optical signal. The effective distance of the irradiance measurement is definedby the adapter which is set as 5.5 mm to the front panel of the light housing. With the known
ICF of the system, the spectral irradiance of the enclosed irradiance light source can be
determined. The calibration is repeated by comparing with a second QHT reference standard
lamp. The average value of the two measured spectral irradiance is reported if there is no
significant discrepancy between the two measurements (with En ratio < 1).
3. Results
The spectral range of this calibration service is from 300 nm to 850 nm. The measurement
model was validated by GUM framework in accordance with the JCGM 100:2008 “Evaluationof measurement data – “Guide to the expression of uncertainty in measurement” and JCGM
101:2008 “Supplement 1 – Propagation of distributions using a Monte Carlo method”.

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The measurement uncertainty components are evaluated, which include the calibration
uncertainty and drift of the reference standard lamp, alignment error and the accuracy indistance measurement, wavelength scale error and bandwidth effect of the double
monochromator, non-linearity of the PMT and the current to voltage amplifier, stray light effectof the monochromator and the instability of current supply to the reference standard la mp.
The expanded measurement uncertainty for the spectral irradiance calibration is estimated tobe 2 % from 440 nm to 850 nm. For spectral range from 300 nm to 430 nm, the calibration
uncertainty of the reference standard lamp is higher and therefore lead s to an increase in
expanded measurement uncertainty to about 3 %.
4. Conclusions
A fiber-coupled system has been set up at our laboratory for the calibration of enclosed
spectral irradiance light sources. The spectral range of this calibration service is from 300 nm
to 850 nm. The measurement uncertainty is estimated to be 2 % to 3 %, which can meet thedemands for spectral irradiance calibration from the testing and certification industry.

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PO34
OPTIMIZATION OF A MOBILE METHOD FOR MEASURING ROAD LIGHTINGCHARACTERISTICS (LUMINANCE AND ILLUMINANCE)
Alena Kuznetsova, Mikhail Fedorishchev, Anatoly Chernyak
Russian Lighting Research Institute named after S.I. Vavilov, RUSSIA
kab@vnisi.ru, fma@vnisi.ru
Introduction
The main task of outdoor lighting is to ensure safe and comfortable movement of vehicles andpedestrians, which is achieved by ensuring the visibility of objects on the surface of the
roadway. The most adequate value for visibility level is pavement luminan ce, to which ahuman eye reacts. However, a number of conditions need to be fulfilled in order to measure
this - a stretch of roadway which is long and straight in plan, with no junctions with otherilluminated roadways, and which has a clean, dry road sur face. In those areas where
luminance measurements cannot be made because at least one of these requirements,
pavement illuminance measurements should be made.
The stationary measurement technique is more common, but is complicated and time consuming, and therefore expensive. In addition, to ensure the safety of the personnel, theblocking of traffic in the measurement area is required. Therefore, given all the difficulties,
luminance and illuminance measurements by stationary methods are not carried out en masse.
Mobile methods of measurement of standardized parameters on roads allow avoiding theabove problems, and modern measuring tools, which ensure implementation of mobile method,
allow obtaining reliable results. At the same time the productivity of mea surements is
considerably increased, which allows for monitoring of lighting installations during their
lifetime.
Main partA mobile method of measuring road surface luminance has become possible due to theemergence of high-performance digital CCD-based luminance meters. Such devices make itpossible to record and save luminance images to computer hard disk, which fall into the fieldof view of the lens, by taking pictures from a moving vehicle. In this case, it is possible tosimplify and accelerate the process of measuring luminance, increase the number of surveyed
areas in comparison with the stationary method.
However, given the nature of the digital measuring equipment, it is essential to ensure thatthe measurement results obtained are valid while on the move.
Optimization of a mobile measuring method involves identifying and investigating all possible
measurement uncertainties associated with the specifics of the method.
In the course of this work, the following main errors are considered:
1. Luminance image fixation time errors due to:-movement of the vehicle (speed of movement, integration time);-

oscillations of the luminance meter in different planes (due to roughness of the roadsurface, operation of the vehicle engine);-

power supply of the luminance meter from the vehicle on-board network through thevoltage converter;-changes in the device temperature due to continuous long-term operation.

2. Errors of measurement results processing, arising from:228

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during selection of a measurement polygon by the operator;-

forming scanning of a selected fragment (distortion of real sizes of objects);-

during plotting of control points on the selected polygon (real area covered by the selected
field characterizing the polygon point);-

due to the low resolution of the matrix.

The characteristics of the digital luminance meter used have been investigated:-comparative measurements of luminance parameters of road surfaces by stationary
method by photoelectric luminance meter and by stationary and mobile me thods by digital
luminance meter;-

laboratory tests of the digital luminance meter at low luminance levels;-

evaluation of the effect of different vehicle speeds on the measurement result;-evaluation of influence of control points vicinity size during luminance image processing on
resulting values of average road surface luminance, general and longitudinal luminancedistribution uniformity.

For illuminance measurements by mobile method in accordance with CIE 194:2011 four
photometric heads are mounted outside the vehicle so that their receiving surface is parallel
and as close as possible to the road surface. When processing the data in a special program,the signals from the front sensors and their corresponding rear sensors are paired at a time
when they are both at the same point in space.
In order to optimization the method, the main uncertainties were considered, which include
errors:-the measuring instruments used;-approximations of the results obtained by processing (summation of signals from s ensors
located along a straight line to the front and rear of the vehicle, vibrations transmitted fromthe vehicle engine, etc.);-

systematic, caused by the location of the receiver surfaces above the road surface;-

repeatability (repetition of measurements of the same object by the same laboratory withina short period of time).

In the present work:-values of basic errors of the mobile method with the help of mathematical model andexperimental sample have been established;-recommendations for application of the mobile lighting laboratory were developed;-

methodology for measuring illuminance on the road surface was developed.

Conclusion
The following has been carried out:-developed technical requirements for mobile systems to measure the luminance andilluminance on the road surfaces and for the components of the system (the calculation
clarified the optimal design parameter of light sensors to illuminance measure);-comparative experiments were carried out to show the difference in quality and sp eed ofmeasurements between the mobile and stationary measurement methods;-

the values of basic uncertainties of the mobile method were investigated;

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the method for obtaining measurement results of average luminance, general andlongitudinal uniformity of road surface luminance distribution as well as average luminanceand its uniformity on the road surface were determined;-

requirements for measurement conditions, presetting of measuring equipment, retrofittingof the vehicle are formulated;-

requirements for luminance image processing and the resulting road illuminance data set
were established;-

estimation of the relative error of the measurements.

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PO35
INFLUENCE OF ROTATION ANGLE OF SQUARE LUMINAIRES ON MEASURED
PHOTOMETRIC PARAMETERS OF INDOOR WORPLACES
1

Mokran, M.1, Dubnicka, R.1
Department of Electrical Power Engineering, Faculty of Electrical Engineering andInformation Technology, Slovak University of Technology, Bratislava, SLOVAKIA
roman.dubnicka@stuba.sk

Abstract
1. Motivation, specific objective
Square shaped and round shaped LED luminaires are often used in the various lighting
systems of indoor workplaces. The luminous distribution curve which represents spatial
information of luminaire appears to be symmetrical. In fact, these lu minaires may not always
have an exact symmetry in the luminous distribution curve diagram due to imperfections in the
optical system of luminaires. The main problem with these luminaires can already occur whenmeasuring luminous intensity distribution curves in a photometric laboratory due to incorrect
determination of symmetry by a testing engineer. Due to the design reasons of the luminaire,
it is often very difficult or even impossible to determine the photometric axes of the luminairein the case of shape of square as well as round shape luminaires. This can cause a little
difference in the angle of rotation axis of the luminaire in the lighting design calculation tooland simultaneously in the actual lighting systems after mounting luminaires according toproject documentation. This condition can lead to a situation where the quality parameters of
the lighting system do not meet the requirements of the standards treating indoor workplaces.
Such a situation is, of course, undesirable and can cause signifi cant financial losses forinvestors. Because of other parameters entering into the lighting calculation by means oflighting calculation tools and mounting of the indoor lighting system in the practice, whichcause a difference between the calculated and measured parameters without assumption of
non-symmetry, it is necessary to a little bit oversize the system to some extent to ensure meetrequirements of standards. This oversizing at design level is after that limited by the energy
efficiency of the buildings and by the financial requirements of the investor. In order for thelighting system to be as efficient as possible and to meet all qualitative and quantitative
parameters defined by the relevant standards, it is necessary to pay attention to the indivi dual
input parameters in the design process of indoor lighting systems.
2. Methods
In the research work were performed photometric measurements of various square shaped
and round shape LED luminaires used in the practice based on common methods by means o fgoniophotometery using devices properly metrologically characterised with traceability toprimary standards. After measurement exchange photometric files were created in LDT, IES
format as input for lighting calculation tools to compute photometric param eters according tostandards for lighting systems of indoor workplaces with assumption of various rotation angle
orientations which can occur in the practice when luminaires are mounted according to project.
Influence of the position and rotation will be investigated by means of lighting calculation tools
which are broadly used in the practice by designers (e.g. Dialux, Dialux EVO, Relux etc.).
Even more approach for evaluation of uncertainty as the Monte Carlo method wasinvestigated and they will be presented as a method for estimation of some predictions forlighting designers who shall assume differences related to the problem described above. For
photometric quantities were evaluated from the lighting calculations according to standards
defining requirements of particular lighting systems of indoor workplace.
3. Results
Based on the results of lighting calculation of photometric parameters for indoor workplaces
using chosen square and batch of luminaires lighting systems were identified parameterswhich contributes to the significant difference lighting systems installations assuming position

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and orientation of luminaires in combination with uncertainty measurement which significantly
contribute to the of the uncertainty estimated by GUM document. Then ba sed on the result
values of these parameters should be considered how to treat with uncertainty and to beaware about orientation of luminaire in the design process and in the practice at mounting ofluminaires will be presented in the paper.
4. Conclusions
The paper deals with the problem that can occur when the photometric axes of the luminaire
after the mounting of luminaires of the indoor workplace lighting system are not identical withthe photometric axes given in the project documentation. Lighting c alculations of photometricparameters by lighting calculation tools has shown differences when orientation of luminaires
is not respected at the design level or mounting process of batch of tested square and roundshaped LED luminaires.

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PO36
ESTIMATION OF COMPLEX LIGHT DISTRIBUTION CHRACTERISTIC
BASED ON LIGHT FIELDS
1

Tamura, T.1, Ohno, M.2, Nakazato, Y.2, Hirai, K.1
Chiba University, JAPAN, 2 Stanley Electric Co., Ltd., JAPANtakara@chiba-u.jp

Abstract
1. Motivation, specific objective
Automobile headlights are subject to strict measurement of light distribution characteristic interms of safety. The conventional method for measuring light distribution characteristic is torotate the headlight by means of a goniometer and to obtain the illuminanc e distribution foreach angle by measuring the incident light into a radiometer which is located 25 meters awayfrom the headlight. This method requires a darkroom larger than 25 meters, and in addition, it
takes more than 30 minutes for a single measurement. In recent years, the number of types ofheadlights has been increasing due to the appearance of LED lights and the diversities in thefunctions of headlights themselves. As a result, the number of manufactured headlights is
also growing, and it is difficult for conventional method to cover the measurement of headlight
distribution characteristic in terms of space and time costs. In order to solve this problem, we
propose a light field-based method for measuring complex light distribution characteristic insmall-space and short-time measurements.
2. Methods
The light field is a quantization of light as rays and representation of that rays as four dimensional parameters of coordinates and angles. By using this concept, light can be treateddiscretely as rays, and the light distribution characteristic of the light source can be
determined geometrically. Our method of light distribution characteristic measurement is tomeasure the intensity of light of a plane with a certain range at a distance from the lightsource, and then to estimate the intensity of light of the plane at a distance from the lightsource based on the intensity of light. Specifically, the light emitted from the light source isdiscretized as a flux of rays based on the light field concept, and the light transport equation
is formulated with the intensity of light on the plane through which the rays pass as the left hand side and the product of the transfer function (known as a light transport matrix) of therays and the intensity of light of each ray as the right-hand side. In this case, the intensity oflight on the plane of the left side is known by measurement. Since the parameters of the rays
are arbitrarily set, the transfer function of the rays on the right -hand side is also known.
Therefore, this light transport equation can be solved for the intensity of each ray. Once theintensity of all the rays is obtained, the intensity of light at any given point can be calculated.
Since illuminance is derived from luminous intensity and distance , determining the intensity oflight at a given point is synonymous with determining the light distribution characteristic of thelight source. By using our method, light distribution characteristic can be measured only bymeasuring the intensity of the light plane at a small distance from the light source, eliminating
the need to use a darkroom larger than 25 meters as used in the conventional method. Also,
depending on the parameters, it is possible to measure the light distribution characteristic in ashorter time than the conventional method.
3. Results
Based on the theory described in Section 2, the intensity of the light plane at 50 to 500 cm
away from the light source was created by computer simulation, and the intensity of light ofeach ray was calculated from the light transport equation formulated based on the intensity oflight plane. The light source is defined as a 6 cm × 6 cm rectangle with several point lightsources inside the rectangle, and each point light source emits one ray for each point of theintensity of the light plane at 25 meters away from the light source. Also, this experimentassumes a vacuum. The experiment showed that the intensity of light plane values obtained

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by the calculation has an error of up to about 17% compared to the correct intensity of lightplane values. In this case, it took about 24 minutes for all the calculations to be completed byusing QR decomposition algorithms for solving the light transport equation. The same
experiment was conducted by varying the number of point light sources that make up the lightsource. This experiment also showed that the error decreases as the number of point sourcesthat make up the light source increases. These results suggest the possibility of performing
light distribution characteristic measurements within a narrower range and in a shorter timethan conventional method.
4. Conclusions
In this study, we proposed a method to estimate the light distribution characteristic of a lightsource from the intensity of the light plane at a small distance from the source based on thelight field. We have also conducted computer experiments to show that our method has thepotential to measure light distribution characteristic in a narrower range and in a shorter timethan conventional method. However, in this study, the intensity of the light plane is calculated
on a computer assuming a vacuum. When measuring light distribution using actual headlights,
a method to correctly measure the intensity of the light plane is necessary. In the experime nt
conducted in this study, QR decomposition is used to solve the simultaneous equations, andthe computational complexity is, which means that if the experiment is conducted at ahigher resolution, more time will be required for the calculat ion. Consequently, a more
efficient algorithm is required to perform more accurate measurements in less time thanconventional method.

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PO37
AN OVERVIEW OF THE IMPACT OF STRAY LIGHT FROM COMMERCIAL
GREENHOUSES
Bertin, K.1, Mucklejohn, S. A.2, Raynham, P.M.3, Zissis, G.1, Moutsi, A.2, Preston, B. 2
LAPLACE UMR 5213 CNRS-INPT-UT3, Université de Toulouse, 118 route de Narbonne,
31062 Toulouse CEDEX 9, FRANCE, 2 Ceravision Limited, 28 Tanners Drive, Blakelands,
MK14 5BN, UNITED KINGDOM,
3UCL Institute for Environmental Design & Engineering, University College London,
14 Upper Woburn Place, London WC1 0NN, UNITED KINGDOMCorresponding author: kevin.bertin@laplace.univ-tlse.fr

1

Abstract
1. Motivation, specific objective
Lighting systems for commercial greenhouses and grow-rooms are often specified in terms ofphotosynthetically active photon flux density (PPFD with units of mol.s -1 .m -2 ), over thephotosynthetically action range (PAR) of 400 nm to 700 nm. However, this approachoverlooks the influence of the spectral output of the lightsource. Such specifications neglect
the importance of radiation falling beyond the PAR range despite the large body of evidence
that shows contributions from red, far-red, UV-A and UV-B radiation are essential to ensure
crops develop the same characteristics as if they were grown under natural lighting conditions.
The spectral power distribution (SPD) of greenhouse lighting will not only have an impact on
the health and productivity of the plants being grown but also on pollinators and any bio control species within the space. Similarly, the effects of any stray light emanating from thestructure will be a combination of SPD, intensity and distribution.
Beyond the fact that any artificial light passing through the confines of the structure is a directloss of productivity for the growers (and therefore they have an interest in limiting it), it
becomes even more problematic when it occurs at night. In fact, it is often necessary to keep
the lighting on after the sunset to achieve the Daily Light Integral (DLI) goal of the most light hungry crops, so commercial greenhouses are slowly becoming a larg er contributor to the
Artificial Light at Night (ALAN). A well-known effect of the ALAN is the sky glow whichinterferes with astronomical observation. However, the increase in the number of lightsources
in urban areas and the evolution of the SPD (especially LED blue-rich light) of these sources
have highlighted other potential effects of the ALAN on wildlife and human rhythms.
It is indeed very difficult to understand the complexity of interactions and balance in wildlife
but it is proven that the ALAN has an impact on nocturnal and diurnal pollinators. Many
nocturnal insects, including pollinators like moths, use moonlight to navigate and will bedisoriented by the ALAN, potentially disrupting their pollination activity. This also becomesproblematic inside greenhouses where the stray light at night may cause unwanted species to
be attracted. The unintentional introduction into Europe of the Asian Hornet (Vespa velutina),
which preys on honey bees and is attracted by light at night, is one such example.
This article aims to provide an overview of the potential impacts of stray light from commercial
greenhouses. The work concentrates on the potential disturbance to wildlife rather than theimpact on local residents. It should help professional growers to und erstand the negative
effects of ALAN and help them to adapt in order to mitigate their negative effects, for example
with horizontal and vertical light restricting screens, while enhancing beneficial effects.
2. Methods
The authors created descriptions, including quantitative values of their spectral output 380 to
780 nm, of a series of lightsources for horticultural applications based on commerciallyavailable products. The properties of these generic lightsources were then used in conjunction
with luminaire IES files to design lighting installations for a greenhouse measuring 81 x 50 m.
Lighting designs we calculated by predicting the radiation on a reference surface using235

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distribution factors generated by an extension to the method described in CIE docume nts as
the greenhouse was much larger than any room previously considered. The spacing to heightratio was checked to ensure uniformity of irradiance. The lighting designs were reproduced
using commercially available software. The authors quantified variou s indicators including
some recommended by an obtrusive light standard: the maximum value of illuminance in thegreenhouse (lx), the upward light ratio (dimensionless), the total luminous flux emitted fromthe structure (lm), the installed power per unit of illuminated area (W.m -2 ), the annual energy
consumption indicator per unit of illuminated area (kWh.m -2 .y -1 ). The results from the latter
were used to evaluate the stray light emanating from the structure and how growers could
adapt to limit it. The authors acknowledge that the lx value is not a relevant quantity to assesslighting action for the plants and it is used here only to estimate the light pollution.
3. Results
The results from the lighting design calculations enabled the authors to characterize theintensity and distribution of stray light emitted from the greenhouse structure. For a PPFD
target of 300 mol.s -1 .m -2 using our generic 1000 W HPS lamp properties in a typicalhorticultural luminaire would have a power requirement, including control gear, of 222 W.m -2
yielding PPFD of 335 mol.s -1 .m -2 with uniformity 0.56 and average illuminance on the sidewall of 7995 lx. An installation of our generic 1000 W metal halide lamps in the same
luminaire would result in a power requirement of 274 W.m -2 with values for PPFD, uniformity
and average side wall illuminance of 342 mol.s -1 .m -2 , 0.74 and 9500 lx respectively. However,
although these installations would have similar PPFD values, the number of lamps needed
and the spectral power distribution of the lightsources are very different and would havediffering impacts not only on the crop growth but also on the stray light. Thus, the stray lightwould have different influences on the wildlife in the surrounding area.
4. Conclusions
Although stray light from greenhouses could be reduced by the use of horizontal and verticallight restricting screens these would lessen the benefits from using natural light unless they
were deployed only when artificial lighting was being used. The economic burden oncommercial growers would be difficult to justify in the absence of regulations and enforcement.
A better approach might be to adopt standards that would provide guidance for intensity anddistribution limits depending on SPD. Current standards for obtrusive light from outdoor work
places do not seem suitable when applied to greenhouses. In particular, they do not consider
the problem of sky glow. The authors make recommendations for new metrics to characterize
stray light from commercial sized greenhouses.

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PO38
REGISTRATION OF LIGHTING AND USE OF BUILDINGS IN THE SCOPE OF IEA SHCTASK 61, THREE CASE STUDIES
1

Matusiak, B.S.1, Nazari, M.1, Sibilio, S.2 Sokol, N. 3
Norwegian University of Science and Technology, Trondheim, NORWAY,
2
University of Campania Luigi Vanvitelli, Aversa, ITALY
3
Gdansk University of Technology, Gdansk, POLAND
barbara.matusiak@ntnu.no

Abstract
1. Motivation, specific objective
This paper has been developed in the frame of the IEA Task 61 Sub task A User perspective
and requirements. The aim of the study was to register occupancy pattern and user’s
behaviour for the purpose of investigative use of both daylight and electric light in publicbuildings. The occupancy data in public buildings can provide important and valuable
information for lighting designers, architect and engineers who want to optimize the use ofresources, both energy and lighting based, aiming at the same time at satisfying user’s
requirements. Even though there is a wide range of research in lighting control systems andenergy saving methods in public buildings, there is a need for updated and accurate data ofoccupancy in public buildings, which is best done by undertaking field -studies.
To address this, due to historical relevance, well representativeness, and accessibility, aschool in Norway, an office in Italy and an industry building in Poland were selected.
2. Methods
The Self-Report and light technical measurements are the two data collection methods
applied in this study simultaneously. The Lighting Diary form collects participants’ data (age,number of people using the space, etc.) as well as movements and activities. Those are
related to the occupation of the space, switching of the luminaires and adjustments of thecurtains. The diary forms were slightly modified to consider the local conditions (type ofluminaries, presence of projector, blinds/curtains, etc.). During a meeting with users of thespaces prior to the registration day, the registration method was expl ained.
The second collection method consists on several light technical measurements that havebeen performed. They mainly included illuminance on the task area, in the school also CCT,CRI and SPD. For outdoor, the illuminance on the façade every 15 minu tes. Three scenarios
were considered: only_Daylight, Daylight+Electrical, and only_Electrical. In the school, HDR photography was taken from positions representing the teacher and a student.
3. Results
Considering the school sample, the teachers in six different classrooms registered everychange of the activity or movement in dairy forms during the working hours. All of the classes
switched on the general lighting at the beginning of the day, the light was switched on and off
few times during the day and mainly switched off after the working hours. The measurementshows that in the wintertime the daylight does not reach the standard level that is needed ona task (300lux) so keeping curtains open or close does not make a huge difference on thenecessity of using electrical light. But in spring and summer, the level is easily reached on thetask positions close to the windows. The use of artificial lighting enables more illuminated task
positions and better uniformity.
Considering the office sample, it must be noted that the measurements have been taken on asingle day (March 2020) and they are related to a single-occupant office and multi-occupants
large open space equipped with vertical internal blinds. For both offices the ambient lighting
and desk lamps can be controlled manually, and users switched on the general lighting at the237

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beginning of the working day and switched it off at the end of the day. From the Diary vsmeasurements comparison, it appears that the change in general lighting is neither relat ed tothe outdoor nor to the indoor light level, even though light levels on the desks were higher
than the recommended level in offices (300-500 lux): i.e. the changes in the electrical lighting
follow the occupancy pattern of offices, not the light level s. It seems that the relationshipbetween changes in vertical blinds and indoor illuminance values is not considerable as well.
In the industry, the results indicate that most of the responders did not control lighting
conditions. The prerequisite lighting conditions are managed only in a severe visual orthermal discomfort cases by individual responders by switching on/off electrical lighting or
shading the windows.
4. Conclusions
In the school, the electrical light had remained on during the night in one classroom.
Considering the whole building we may expect that 17% of the classrooms keeps the lighting
on after working hours, which is obviously an unnecessary electrical lighting energy.
Regarding the use of general lighting and curtains adjustments, it c an be expected that theusers would favour closing entirely the curtains while the projector is used, leave the curtains
on afterwards and then using the electric lighting the rest of the day, this regardless of thetime of the day and the year. A control system of lighting system in a modern school should
strongly consider use of projectors.
In the office, the daylight conditions in the multi-occupant’s room create two different “lit” area
as a function of the users’ position with respect to the window: a first zone near to the middleof the window and the second zone on the window sides. In the first zone, there is a higher
availability of daylight, allowing to reduce the energy consumption associated with the electric
light. In the second zone, the daylight levels are much lower, thus requiring a higher
integration with electric light. The results highlight the need to improve the electric lighting
system to guarantee the minimum recommended light levels inside offices. Considering thedifferent daylight availability on the desks, a potential energy saving, compared to the current
electric light usage, could be achieved by using a control system able to adjust the electric
light contribution to the specific need for each user’s position.
In the industry many responders presented very strong qualitative opinions about their lighting
conditions and dissatisfaction with the current state but admitted that they usually adapt towhat is available. The qualitative results of measured or simulated conditions illust rates
various scenarios that indicate the need to use of integrated lighting control systems to
improve users’ satisfaction.
The results show that the use of general lighting in the spaces does not necessarily follow thechanges of light level outdoor and even indoor, instead it follows the occupancy pattern anduse of the space.

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PO39
OPTIMIZING CAMERA PLACEMENT FOR A LUMINANCE-BASED SHADING CONTROLSYSTEM
Mentens, A.1, Scheir, G.H.1, Lataire, J.1 Jacobs, V.A.1
1
Vrije Universiteit Brussel, Brussels, BELGIUM
Arjen.Mentens@vub.be

Abstract
1. Motivation, specific objective
Shading control systems are often illuminance-based whereas daylighting metrics as theDaylight Glare Probability (DGP) are calculated based on luminance values. In previous
academic studies, a luminance camera or HDR images obtained with a commercially available
camera are used to assess the DGP of the user. Such cameras are traditionally mounted
close to the user and aligned with his/her view direction. In real office environments, thisposition of the camera is impractical.
Based on machine learning techniques applied to simulations, we have recently found astrong relation between the DGP from an observer's viewpoint and the DGP from a ceilingcamera.
This research aims to validate the aforementioned study in a real office environment. The
shortcomings of the simulation results are pinpointed and the obstacles for a realistic
application are addressed.
2. Methods
A case study setup mimicking a real office environment is used to allow f or an observer to sit
perpendicularly to a window. One camera is placed close to the observer and aligned withhis/her view direction. A second camera is attached to the ceiling and is facing downwards. A
comfort assessment is based on an HDR image from both camera positions at the same
instant.
Based on machine learning techniques applied to simulation, the sun direction was shown tobe an informative additional input for correlating the two DGP values and is therefore used ina machine learning algorithm to perform a regression analysis between the observer's
viewpoint DGP and the ceiling camera DGP.
3. Results
At the time of writing, the setup was built and we are now starting the measurements.
However, we expect that the first results will emerge at the end of June, in due time topresent the results at the conference.
4. Conclusions
As the results of the study will only be expected by the end of June, it is too early to draw any
conclusions from the measurements. However, we can already state that based on machinelearning techniques applied to simulations, it was possible to get a clear correspondence
between a comfort assessment from the ceiling and a DGP assessment from the user.

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PO40
A REAL-TIME INTEGRATIVE LIGHTING SYSTEM FRAMEWORK BASED ON MACHINELEARNING
1

Durmus, D.1
Penn State University, University Park, USA
alp@psu.edu

Abstract
1. Motivation
A smart lighting system consists of several functions and components, such as data collection
through sensors, data analysis through software, decision-making through lighting controls,
and light output through light sources. Data collected from sensors can be very large, complex,
and cost-prohibitive for individuals to analyze. To address this problem, data science methods
can be used to capture, store, and analyze information in real-time to extract value, andperform adaptive and predictive user behavior analytics. A lighting system that detects datafrom occupants and the environment can adjust its output in real -time to meet predefinedgoals (e.g., energy efficiency) as well as user-dependent specific goals (e.g., visual comfort).
2. Algorithm-based integrative lighting system
The proposed integrative lighting system can adjust the light output by analysing the sensed
data to address occupants’ ever-changing conscious and subconscious needs without
sacrificing energy goals. Such adaptive systems require human input (often referred to as
training) due to the limitations of the artificial intelligence systems. Adaptive systems are said
to be hierarchical where a first-order change aims to suit the immediate environment, and asecond-order change reduces the number of errors needed to achieve first -order mechanisms.
Following this course, real-time tunable lighting systems require two types of input : initial setup and feedback loops. Initial (conditions) set-ups provide the fundamental functions of thelighting system, such as turning on the light with the human presence or dimming for specificvisual task needs. The success of the initial conditions of the system depends on theunderlying human factors research investigating the human-light interaction. However, initialconditions are based on visual perception studies that are often based on average observers.
For example, the results from visual perception studies may not be enough to meet every
users’ needs due to interobserver variations, especially when populations with special needs(e.g., low vision occupants) are considered. To maintain the adaptive lighting system’s
accuracy and user satisfaction, a corrective structure (error checking mechanism) is required
based on a feedback loop. The feedback loops can be maintained using artificial intelligence(AI) techniques.
The light output of an integrative lighting system can be adjusted by using t he information
received from sensors. The data are collected from users (i.e., occupancy, user position,
speed, heart-rate, respiratory rate) or the environment (i.e., ambient light, weather forecast,temperature). Data collected from sensors are processed by the software, and the light output
is adjusted according to predetermined parameters. Today, parameters used in smart lighting
systems (e.g., illuminance levels) are rudimentary and limited in scope. The data collected
through sensors can be used to build an integrative lighting system to address occupants’various needs. Parameters such as visual adaptation, lighting quality, visual discomfort, visual
attention and non-visual response to lighting should be investigated, as well as theconventional parameters such as energy intensity and illumination levels.
Evolutionary algorithms, especially genetic algorithms, have been widely used in engineeringand mathematics to solve complex problems. In lighting research, genetic algorithms are used
to reduce energy consumed by lighting, increase lighting quality, reduce damage to artwork
caused by optical radiation, and balance electric lighting and daylighting. Optimization studies
foresee smart lighting systems with adaptable sensing and emission capabilities. For example,
an adaptive system can optimize the spectral power distribution (SPD) of a light source to240

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reduce light absorbed by objects. The absorption minimization system can reduce energy
consumption between 44% and 71% without causing perceptible shif ts for individual colours.
Visual assessments support the idea that optimizing the light output can yield energy savings
without sacrificing visual satisfaction. Recently, a similar advanced lighting system prototype
has been built to spatially and spectrally optimize the light output sensing the data fromobjects. Other researchers found that energy savings up to 55% were possible whenalgorithms were deployed to optimize typically conflicting parameters, such as illuminanceand energy consumption.
Although several studies operationalized various algorithms, a real-time application has notbeen applied in the domain of lighting and perception research. Other disciplines have used
evolutionary algorithms to achieve tasks in real-time. For example, studies investigatedminimizing pollution in wastewater, GPS attitude determination, noise control, thermal massestimation, and recognition of road traffic signs. Fundamental and applied research studies
are needed to identify the temporal and spatial characterist ics of the human visual and nonvisual response to light followed by proof of concept studies.
3. Challenges
Benefits promised by integrative lighting systems come with challenges, such as
interoperability serviceability and interchangeability issues. Cyb ersecurity and lack of user
control may bring on additional challenges by increasing the reluctance to adopt newtechnologies and systems. Another potential issue is the conflict between humans’ biologicalneeds and psychological desires. For example, users may desire a light setting that isinherently detrimental to their wellbeing. Although there are possible solutions for a similar
issue, the conflict between different users, there is no framework to solve the conflict between
occupants’ biological needs and psychological desires.
4. Conclusions
The growing interest and investment in smart lighting systems indicate that the infrastructure(e.g. sensors, tunable light sources) for next-generation lighting systems will be widely
prevalent in the future. However, the analysis and use of the big data generated by thesesystems require more advanced techniques to fulfil its destiny. A real -time integrative systemframework can enable adaptive lighting systems to meet both energy efficiency goals andoccupant needs (user satisfaction and wellbeing) by integrating into other advanced building
evaluation and control systems, such as digital twin structures. The real -time light adjustment
can also enable building management systems to become proactive instead of rea ctive, makepredictions and perform preventive maintenance, extend the lifespan of buildings and its
components, reduce negative environmental impacts, and create pleasant and productive
work environments. The real-time integrative lighting system can also be adopted to otherapplication areas, such as horticulture where plants are considered the end users instead ofhumans.

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PO41
HIEQLAB: A FULL-SCALE FACILITY TO INVESTIGATE THE THEMES OF INTEGRATIVE
LIGHTING AND HUMAN PERFORMANCE WITH A MULTI-DOMAIN APPROACH
1

Pellegrino, A.1, Giovannini, L.1, Lo Verso, V.R.M.1,Favoino, F.1, Serra, V1.
Politecnico di Torino, Energy Department, TEBE Research group, 24, corso Duca degli
Abruzzi – 10129 Torino, ITALY
Anna.pellegrino@polito.it

Abstract
1. Motivation, specific objective
Buildings quality and performance play a major role in our societies. The building sector is
responsible for a great share of the global energy consumption and, due to the large amountof time people spend in indoor environments, buildings can greatly influence human healthand wellbeing. For this reason, improving the occupant’s wellbeing through high quality indoor
environments is becoming of foremost importance for most of the actors involved in thebuilding sector. Researches on building environmental quality and performance can be
performed through different approaches: (i) dynamic numerical simulations, which are
effective to quickly compare results for different building configurations or climate conditions,but are limited in including the “occupant factor”; (ii) in-field studies, which allow analysing
realistic conditions, but usually with poor-controlled indoor environments; (iii) full scale test
facilities and living labs, which allow carrying out studies under controlled realistic conditions,directly involving the final users. This last approach can significantly improve the scientificresearch on energy efficient and healthy buildings by fostering a synergistic and user -centred
innovation process. Within this framework, the TEBE (Technology, Energy, Building andEnvironment) research group at Politecnico di Torino has designed and is real izing the
HIEQLab (Health, wellness and Indoor Environmental Quality Laboratory), a full -scale facility
conceived to reproduce a real-life, flexible environment, where envelope technologies,
services (HVAC and lighting) and controls are tested and implemented with a user -centred
approach. The primary scope is that of developing researches on human performance,
comfort and well-being and on the energy performance of building environments in acompletely controlled real space. Users are involved in the research activities, becoming
active players in the evaluation process and in the development of building components anddesign strategies which address health, well-being and IEQ requirements.
2. Methods
The idea underlying the conception of the HIEQ Lab is that of providing a high degree of
flexibility to the facility, allowing its adaptation to different types of experiments. This flexibility
can be found in different aspects, such as the geometrical features of the laboratory, which
can be used as a single space, but a moveable partition allows to transform it in two sub laboratory spaces with identical features. As regards the transparent envelope co mponents,
these can be replaced in terms of the sole glazings or of the whole façade system. Moreover,they can be modified according to the research needs, changing the window to wall ratio(WWR), the type of transparent/opaque materials or adding interna l or external shading
systems. A high flexibility is provided also in the definition of the technical building systems,
since the false ceiling hosting the light fixtures, and other HVAC components was designed tobe re-configurable according to the experimental needs.
In the laboratory, all the environmental quantities concurring in the determination of the IEQ(air quality, thermal, lighting and acoustic) can be recorded, inside and outside the facility.
Moreover, all the quantities characterizing the building envelope and the operation of thebuilding systems will be monitored, as well as the energy consumption of the heating, coolingand lighting systems. Simultaneously, it will be possible to perform subjective analyses
investigating the behaviour and the responses of the occupants.

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3. Results
The characteristics of the HIEQLab will allow investigating the themes of lighting anddaylighting in a completely controlled and monitored real space, also in the presence ofoccupants. A continuous monitoring system of the spectral characteristics of the light outside
and inside the laboratory will allow carrying out researches on the theme of human centric
lighting. It will in fact be possible to consider both the visual and non -visual effects of light,
integrating them in unified strategies to improve the physiological and psychological conditionof the occupants. In more detail, the HIEQ Lab will allow analysing and testing transparent
envelope components, shading devices and smart glazings with the aim of stud ying andimproving the visual comfort condition and the wellbeing of the occupants. The research
activity will focus also on the conception and optimization of control strategies for the dynamic
shading devices and the transparent adaptive façades, aimed a t providing an optimal visual
comfort condition and visual performance to the occupants, Similarly, the HIEQLab will allow
investigating the occupants’ visual comfort condition relative to the design and operation ofelectric lighting systems, as well as the non-visual effects of these actions on the humanperformance. Moreover, involving real occupants in these researches will enable to address
the effects of a long-term exposure to specific sources of light on their phsyco -physiologicalconditions. The study of human centric lighting relative to both daylight and electric lighting
will also allow investigating the integration between these two aspects, devising control logics
for both the daylight and the electric lighting systems able to simultaneously co nsider (andimprove) the light visual and non-visual effects on the occupants’ visual comfort and humanperformance.
4. Conclusions
The laboratory features, its flexibility and the expertise of the research group will allow
carrying out researches and experimental activities with a multi-domain approach. Theinteractions between lighting and daylighting solutions and control strategies with thermal, air
quality and acoustic aspects could be studied, allowing to develop new concepts of human centric IEQ, new metrics for its evaluation, new methods and sensors for monitoring, with theaim of improving the overall comfort and building healthiness in the global framework of Zero
Energy Buildings.

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PO42
ARTIFICIAL LIGHTING DESIGN WITH CONCEPT OF HUMAN CENTRIC LIGHTINGCRITERIA IN CELL OFFICES
Aliparast, S.1, Onaygil, S.2
TURKEYaliparast17@itu.edu.tr

Abstract
Human centric lighting (HCL) is the sum of visual and non -visual effects of light on humans.
Lighting comfort criteria and HCL issue is one of the significan t factors that discusses light’s
stimulations and affects on human mood and activity. The impacts of the luminaires and roomparameters are inevitable to design human-centered general lighting. The study was
conducted through computer simulation to examine how luminaires type can influence vertical
illuminance (Ev) besides recommended horizontal illuminance (Eh) as general lighting throughstandards as EN 12464 along the room. Moreover, evaluating luminaires to deliver Ev to theeye at 1.2 m height, beside horizontal calculation plane at the working plane level (0.8 m) toensure maintaining the required Eh which is suggested minimum 300 -500 lx. We evaluatedfour luminaire types including Recessed Down-lights, Surface Mounted Modular, Surface
Mounted Linear, and Suspended Direct Indirect Linear. With different light beam distributions
to calculate the circadian stimulus (CS) which concerns light as the main stimulus that helps
the circadian clock, and thus circadian rhythms, keep a synchronized rhythm with the 24-hour
day, in lack of synchrony or circadian disruption, we may experience decrements inphysiological functions, neurobehavioral performance, and sleep. The circadian system is
kept in a state of harmony by using different cues, including light in whic h the body reacts in a
way that stimulates the spinal cord cells (ipRGC) - the photomicrographs of non-image of theeyes. According to WELL standards the EML metric is factor of evaluating the building interms of wellbeing. Equivalent Melatonin Lux (EML) is a proposed exchange of stress for
ipRGCs rather than cones. for cell office without access to day light. The office worker shoulddeliver good circadian light to be active during office hours. The goal of study is proposing
evaluation method for convenient lighting design keep productivity of office workers.
Reflectance of room surfaces are assumes as ceilings 70%, walls 50%, Floors 50% without
dark office furniture. The luminaire type, positioning, light distribution curves of luminaires
play important role in transferring Ev, and it showed that the right luminaire type withpositioning reaches the target rate for CS and suitable EML for the best non visual lighting
design. With comparison study we approved that with single colour temperature of 4000K
Suspended Direct Indirect lighting fixtures can achieve targets of HCL. Lighting design results
for cell office should reach EML higher than 150 and CS approximately 0.4-0.3 at office hours
8 – 17am. This study is alternative lighting designs were created in which EML and CS criteria
values would be specified in cell office which is not receiving daylight. The results for 9 pieces
recessed down-light is Eh 714 lx, Ev 387 lx, CS 0.306, and EML 294.12 with total energy
consumption per year of 377.28 kWh. The same cell office with 4 pieces surface mounted
modular Eh 783 lx, Ev 494 lx, CS 0.335, EML 375.44, total energy consumption per year
335.36 kWh. Results for 2 pieces pendant direct indirect lighting fixtures Eh 464 lx, Ev 631 lx,
CS 0.404, EML 479.56, total energy consumption per year 129.95 kWh. Moreover, 6 pieces
linear direct lighting fixtures Eh 739 lx, Ev 442, CS 0.333, EML 335.92, total energy
consumption per year 389.85 kWh. Artificial electrical lighting design should be analyzed inorder to deliver an optimal circadian lighting that can help to increase occupant’s productivity
and performance and energy consumption. The position of worker desk and pendant luminaire
at 2.1m high from floor helps to get Ev 631 lx and 479.56 EML with is the highest amountbetween four type luminaires. Selecting right fixture with appropriate position will assure thealertness of occupant in cell offices without access to day light and save energy.

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PO44
PSYCHOLOGICAL CHANGES DUE TO DIFFERENCES IN THE COLOUR OF THE
ILLUMINATION LIGHT
1

Inoue, K., Kaba, S., Heo, J.
Shimane University of Matsue, Shimane, JAPAN

Abstract
1. Motivation, specific objective
Light constantly changes from things that illuminate around to something to colour the space.
Coloured light is used to create an extraordinary feeling like bars and clubs. In recent years,
with the spread and development of LED lighting and lighting fixtures, space production
previously performed in limited places is now being easily performed in homes and private
spaces. Also, there are needs for environments where people can relax and create a special
feeling in separated spaces since it became difficult to go out due to the influence of COVID.
However, not everyone can use lighting effectively.
Also, regarding the effects of chromatic light on humans, visual acuity, colour discrimination,and impression have been examined. However, although there are reports on thephysiological effects due to differences in colour temperature and illuminance, there are few
studies on the psychological effects when chromatic coloured light is used as illumination light.
Therefore, in this study, we clarify the psychological changes of the mind when people are
surrounded by extraordinary environments.
2. Methods
We prepared eight colours of LED lighting, red, orange, yellow, green, blue, light blue, purple,
and white light. We illuminated the darkroom with desks and chairs by using pendant lights
and line lighting. The darkroom has a width of 3000, a depth of 3000, and a height of 2200,
and four walls are surrounded by dark curtains to set the reflectance to 0. The illuminancewas 4 for red, 7 for orange, 10 for yellow, 8 for green, 2 for blue, 9 for light blue, 6 for purple,and 155 for white. We asked eleven men and eleven women who are 20s,30s to evaluate theimpression of the room while sitting on a chair using the SD method on a seven -step scale.
The positive impression was 3, neither was 0, and the negative impression was -3. The paired
evaluation terms of the SD method are fantastic-realistic, mature-childish, open-closed,
nimble-heavy,pleasant-unpleasant,feminine-masculine,
Fun-Boring,
Familiar-Aloof,
Reassuring-Tension, Quiet-Noisy, Luxury-Cheap, Like-Hate, Bright-Dark, Urban-Country,
Flashy-Simple, Warm-cold, 17 pieces.
3. Results
As a result of the impression evaluation, the impression that the average value was 1 or moreof the absolute value is described. The red colour gave a fantastic, closed, heavy, unpleasant,artificial, aloof, tense, noisy, urban, flashy, warm impression. The orange colour gave apleasant, feminine, friendly, reassuring, favorite, and warm impression. Yellow gave a childish,open, nimble, fun, bright, and warm impression. The green colour gave a fantastic, cheesy
impression. The blue colour gave the impression of fantasy, mature, closed, artificial, aloof,
tense, dark, urban, and cold. Light blue gave a fantastic, pleasant, quiet, favorite, urban,
warm impression. Purple gave a fantastic, mature, feminine, artificial, fun, urban, and flashy
impression. White gave the impression of being artificial, quiet, bright, urban, and cold.
Similar to the psychological effects of colour, red gave a warm impression, yellow gave apleasant impression, a bright impression, blue gave a cold impression, purple gave an adult like impression, a feminine impression, and white gave a bright impression. In addition, green
gave an artificial impression that was different from the psychological effect of the othercolours. We did an experiment about factor analysis to extract common factors. The factor
extraction method is the main factor method the number of factors is one with an eigenvalue

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CIE 2021 - Abstract Bookletof 1 or more, and the rotation method is Promax rotation. Fancy-Realistic, Natural-Artificial,
Fun-Boring, Familiar-Aloof, Reassuring-Tension, Urban-Countryside, Flashy-Sober Focusing
on the factors that give a large load, the factor names are given an extraordinary feeling . Astrong fantasy impression and a strong artificial impression were obtained for red, blue, andpurple. They got a fantastic impression in green and light blue. An artificial impression was
obtained in white and green.
4. Conclusions
Green is regarded as a reminiscent colour for plants which give us a natural impression or arural impression. However in this experiment, green light gave an artificial impression. Basedon these results, it can be concluded that the impression when the entire room is illumi natedby coloured light does not correlate with the symbol of colour.
From the results of factor analysis, it is considered that the low brightness is related tofantasy and artificial impressions in special environments. Moreover, since the naturalimpression was obtained only in orange, it is possible to say it has strong correlation with thecolour rendering properties of the light source. Since strong fantasy impressions wereobtained in red, blue, and purple, it is considered that those with short wave lengths and thosewith long wavelengths in visible light tend to create an extraordinary feeling. In the future, wewill clarify the relationship between wavelength and impression by researching the spectral
distribution of each light source.

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PO44
EVALUATION STRUCTURE ON PREFERENCE OF PAINTING’S APPEARANCE WITH
LOW REFLECTANCE IN THE MUSEUM LIGHTING ENVIRONMENT
1

Maeda, A.1, Oe, Y.1, Yoshizawa, N.1
Tokyo University of Science, Chiba, JAPAN7121563@ed.tus.ac.jp

Abstract
1. Backgrounds and Purposes
When considering museum lighting, required illuminance and correlated colour temperature
are often discussed based on the preference of painting’s appearance. However, therelationship between photometric quantities and the preference, which could be highly
influenced by personal taste and the characteristics of the painting, are essentiallycomplicated. In our previous research, we examined the evaluation structure for explaining
the preferable appearance of paintings (oil paintings), and it was clarified th at the brightnessof the painting, which can be estimated based on the luminance distribution, can indirectly
explain the preference through latent variables such as detail discrimination and appearance
quality.
It has also turned out that the above-mentioned evaluation structure model did not necessarily
apply well to low reflectance paintings. The difficulty of displaying India -ink drawings andpaintings in which black is a dominant colour is often cited as an issue by curators, and there
is strong demand for useful knowledge as to exhibition methods for dark paintings. The
purpose of this paper is to clarify the evaluation structure on the preference of appearances
specific to low reflectance paintings.
2. Methods
The experimental room (width 2900 mm, depth 3000 mm, height 2400 mm) was designed
assuming an actual art museum. All surfaces of this room excluding the background surface
were painted white (N9.5). Two kinds of light sources were used: blue -phosphor white LEDs
for the ambient lighting (Ra: 97, CCT: 3000K, d uv : -0.004) and purple-phosphor white LEDs forthe spot lighting (Ra:93, CCT: 3000K, d uv : -0.005). A spotlight was equipped with the trimming
cutter to illuminate the rectangle-shaped area of the painting surface. There were 167
experimental conditions by combining four experimental variables: illuminance, luminanceratio, painting, and background colour. The luminance ratio was defined as the mean
luminance of the painting divided by the mean luminance of the background. There were ten
paintings, and their reflectance values were as follows: Painting A_6.39%, Painting B_16.4%,
Painting C_31.3%, Painting D_41.6%, Painting E_5.81%, Painting F_12.6%, Painting
G_26.1%, Painting H_40.7%, Painting I_8.20%, and Painting J_9.53%. Painting A to D wereused in 2018’s experiment, Painting E to H were used in 2019, and Painting B, E, H, I and J
were used in 2020. 16 subjects participated in both 2018 and 2019 experiments, and 20
subjects in the 2020 experiment. All subjects were in their 20s with normal colo ur vision.
The experimental process was as follows; 1) The subject adapted to the light environment(100lux, 3000K on the painting) after entering the experimental room. 2) The experimenter set
the experimental condition, and the subject adapted to this co ndition for 30 seconds and thenevaluated the painting. 3) The process 2) was repeated. The experimental conditions were
presented in random order for each subject. There were evaluation items for the whole
painting (brightness, comfortable viewing, preference etc.) and for the details (brightness ofthe detail, preference of the detail etc.).
3. Results
In the previous research, the evaluation structure model on the preference of painting
appearances was derived from the 2018 and 2019 experimental data. In this report, we re-247

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analysed the model by adding the experimental data in 2020. In the first place, four factors
were extracted from the results of the factor analysis (maximum likelihood estimation withpromax rotation). The first factor was named "detail discrimination", the second was named"appearance quality", the third was named "appropriateness of brightness", and the fourth
was named "brightness", which means the absolute perception on the brightness degree ofthe painting and contains the observed variables such as glare and brightness.
The correlation coefficients and the partial correlation coefficients among the evaluation items
for the whole painting were calculated. The item included in the first factor "detail
discrimination" had a high partial correlation with the brightness evaluation. Comfortableviewing in the second factor "appearance quality" had high partial correlation coefficients with
the items classified as the first factor, and the items in the second factor had a high partial
correlation with the preference evaluation. These results confirmed that the brightness had an
influence on the preference through the first and the second factors.
Evaluation structural models were assessed following SEM (Structural Evaluation Modelling)methods. The fit of the estimated model created in the previous research, which had threeobserved variables (brightness, appropriateness of brightness, preference) and two latentvariables (detail discrimination, appearance quality), was first examined, and GF I was 0.967(> 0.90) and RMSEA was 0.088 (<0.10), which could be considered a good fit.
However, applying this model exclusively to the paintings with low reflectance under 10%(Painting E, I, J) made the fit worse, in which GFI was 0.952 (> 0.90) and RMSE A was 0.106(>0.10). On the hypothesis that it would be important to be able to perceive black as “black
itself” when appreciating the dark paintings, the model was modified by adding someevaluation items for the black related details (brightness of the d etail, appearance of black,and preference of the detail). The statistical hypothesis testing results showed that thisrevised model was acceptable, in which GFI was 0.958 (> 0.90) and RMSEA was 0.081(<0.10).
4. Conclusions and Future Prospects
In this paper, the evaluation structure model for the low reflectance paintings was examined.
The result strongly suggests that the preferable appearance of “black” on the painting is
crucial for the evaluation of the dark paintings and a n evaluation structure model specific tothem would be required. In future works we would like to clarify the physical indexes which
can estimate the appropriate lighting for the dark paintings.

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PO46
THE LIGHT OF AMAZON ARCHITECT SEVERIANO MÁRIO PORTO
1

Medeiros, A.D.1, Amorim, C.N.D.2
University of Brasilia, Brasilia, BRAZIL 2 University of Brasilia, Brasilia, BRAZIL
1
medeirosayana@gmail.com 2 clamorim@unb.br

Abstract
1. Motivation, specific objective
Daylight is a welcome design attribute in almost every architecture, but applicat ion inbuildings needs to be planned, understanding comfort and climate criteria. In tropical climates
like in Amazon region, dominated for challenges of avoiding overheating, architecture mustallow access to daylight and view out, but guarantee solar con trol in order to reduce thermal
gains as much as possible. Immersed in these challenges, Severiano Mário Porto left Rio deJaneiro city to work in Amazon region in 1965. In the north of Brazil, developed more than 200
projects and turned as an icon of Brazilian modernism. In 1987, beside Oscar Niemeyer and
Lina Bo Bard was elected like a representant of “the fantastic tropical architecture” by the
French magazine L'Architecture d'Aujourd'hui, as recognition of his design with an own
identity, using resources such as integration and use of local bioclimatic potential, focus oncost optimization, renewable materials and regional labour technicians. Some authors believethat his experimentation leads us to what a Brazilian architect can be, where he showed notjust architectural models to follow, but also an architect profile, through the example of his
performance. In January 2021, Severiano passed away, victim of Covid -19. So, this paper
aims to present the results of a master's research regarding about daylig ht and shading
strategies allied with user’s perspective in Severiano Mario Porto building. The idea is tocombine analysis of architecture and lighting quality in Severiano's projects and a reflection
about user’s perspective.
2. Methods
The method is based in documentary survey, case study selection, analysis of lighting quality
with monitoring protocol support and computer simulation, followed for user’s perspective. For
documentary survey, Severiano Mário Porto's projects was consulted. This material is part of
Research and Documentation Centre, to Faculty of Architecture and Urbanism on Universityof Rio de Janeiro. For a representative analysis, it focused on case studies projects
developed by the architect in Boa Vista city, extreme north of Brazilian Amazon. It was
identified buildings with good conservation stage, in relation to original project. So, applied
the Brazilian standard about Valuation of Goods of Historical and Artistic Heritage as an
instrument. This standard parameter analyses the original project and classifies buildings
according to the state of conservation and integrity, in order to appoint it like preserved,
restored or uncharacterized. To identify lighting quality and the strategies for daylighting incase studies, the methodology proposed are morphological diagrams. Through technicalpieces, such as location, floor plans and cuts, it is possible to develop results in a report that
presents the architectural solutions found. So, on-site verification of the lighting condition wasdetermined, using like guidelines monitoring protocols for International Energy Agency. The“Monitoring Protocol for Lighting and Daylighting Retrofits” and the “Monitoring Protocol to
Evaluate User-Centered Integrated Solution” presents procedures to verify the lighting
condition in an environment, based on consolidated references. The technical aspects
investigated were illuminance average (grid based and on task), uniformity, reflectance, viewout, circadian potential, and user’s perspective. Finally, was d eveloped computer simulationof daylight by DesignBuilder, version 6.0, and Radiance program, in order to compare data of
on-site monitoring (modified design) with the original condition on Severiano Mario Porto
design.

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3. Results
According to the collection of Severiano Mário Porto, the architect produced institutional,
commercial, residential, educational and hospital projects, with some on an urban scale.
Regarding the case studies in the city of Boa Vista, 14 projects were identified, of which 12
were built. In relation of the state of conservation compares to original project, 5 buildings areuncharacterized, 4 adapted, 2 partially preserved and 1 preserved. The morphologicaldiagrams apply in Boa Vista projects by Severiano Mário Porto, the study appoi nt likecommon elements for enjoy daylight in project as: buildings with façades of low reflectanceand specularity, high opening rates on the façades (between 25% and 50%); and apply ofbrises-soleil, cobogos, eaves, marquees, pergolas, and vegetation.
Regarding the monitoring protocol, it was verified the addition of solar control films in all
glass’s windows of the building, with no provision in original project. The measurements show
that, in general, there is not a satisfactory level of average dayligh ting bit when combined,
daylight and electric light offer better results. When analysing the quality of view out, theresults are medium and high. For computer simulation, in this turn, the data demonstrated an
expressive potential of daylight illuminance values for Spacial Daylight Autonomy and levelsof Annual Sun Exposure was around 25% of the hours of the year, only appearing in areas too
close to windows. Finally, with Useful Daylight Illuminance results, it is clear that, originally,
there building have a great vocation to use daylight in all verified rooms. However, theapplication of the questionnaire to users showed a low level with daylight satisfaction on
workstations and 86.5% of users answered never use only daylight on your workstation.
4. Conclusions
The architecture developed by Severiano Mário Porto has a wide repertoire of how promote
the lighting of Amazon buildings in a passive way, matching with good shading solutions. In
any case, is urgent to recognize the work done by the studied arch itect, without, however,keeping the buildings obsolete, since, as seen, interventions without criteria compromise thenoticeable quality of their projects. This corroborates for results such the on -sitemeasurement obtained. In terms of daylighting, in a representative study case, results showed
unsatisfactory conditions of illuminance. When inserting the users' perspective, the answers
are aligned with this condition. For computer simulation of daylight, the results showed goodlevels of illuminance and it shows that, despite all the concern with sun protection andshading, Severiano Mário Porto's projects, in their original condition, can achieve asatisfactory performance for daylighting. The design quality verified in the morphologicaldiagrams and in the computer simulation differ from the real condition of use of the building. A
reflection is proposed to understand a typical Amazonian architecture, your quality and thesedegradation process.

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PO47
SOFTNESS OF LIGHT PASSING THROUGH WINDOWS AND ITS RELATIONSHIP WITH
LUMINANCE GRADIENT
1

Sasajima, Y.1, Miyake, Y.2, Ogasawara, K.2, Oe, Y.2, Yoshizawa, N.2
YKK AP Inc., Tokyo, JAPAN, 2 Tokyo University of Science, Chiba, JAPANy_sasajima@ykkap.co.jp

Abstract
1. Motivation, specific objective
Architects and users frequently use window shadings, such as frosted glasses, shoji screens,lace curtains to create high quality of light. This kind of light is sometimes called “soft light”,
and most people feel that it is required in residential spaces. However, the term “soft light” issomewhat vague, and we do not accurately understand what is the “soft light” and how we
can create it. At the moment designing the “soft light” relies only upon the experience andintuition of professional designers.
The aim of this research is to derive physical indexes that can explain the softness of lightbased on its evaluation structure. This will allow us to evaluate the effects of various window
shadings more easily and correctly on the softness of light, which will facilit ate the design ofhigh-quality windows and shadings.
We have already clarified the evaluation structure of the softness of light in our previous
paper by covariance structure analysis, in which perceptual latent variables, such as"gradation", "glare", "brightness", "shadow strength", and "shadow spread", were extracted for
explaining the softness of light. In this report, we will focus on the "gradation", because its
integrated value of the standardized partial regression coefficients from the "gradation" to the“softness of light” was positive and large (0.36) in the evaluation structure. The "gradation"
included observed variables, such as "ambiguity of brightness -darkness boundary (hereafterreferred to as “ambiguity”)" and "brightness-darkness contrast is low (hereafter referred to as“low-contrast”)". The relationship between the luminance gradient calculated from theluminance image and the subjective evaluations of the "ambiguity" and "low -contrast" were
examined through the subjective experiment.
2. Methods
The subject’s evaluation experiment was conducted at a total of 6 rooms, including 2 rooms indetached houses (6m2 and 13 m2) and 4 rooms in accommodation facilities (18 m2). A totalof 44 experimental conditions were set based on the six factors ( Time, Direction, Surrounding
environment, Interior, Window types, and Window shadings). The experiment was conducted
for a total of 10 days from August to September 2020 when the weather was fine or cloudy.
The subjects were 12 to 15 students in their 20s with visual acuity of 0.7 or higher. Theyevaluated the appearance of light by sitting on a chair (diagonally facing the window surface
and the view height was 1200 mm). The subjects adapted to the environment for 10 minutes
in the anterior room in advance. Next, they entered the room, looked around the space for 30
seconds, and then evaluated all 53 items including the softness of light on a 7 -point scale inabout 2 minutes. During that time, the indoor luminance distribution was measured using acamera equipped with a wide-angle lens from the subject's eye level.
The luminance gradient is analysed on the centre line (horizontal) of the part that the subject
may have paid attention to when evaluating soft light. Furthermore, this luminance is firstorder differentiated to obtain the rate of change.
3. Results
Analysis of the wall surface and window surface, which the subject often paid attention to in
the evaluation of the softness of light, showed that there were some relationships between theevaluation of “ambiguity” and “low-contrast” and the luminance gradient on the wall surface.

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When the average absolute value of the rate of change of the wall luminance was not lessthan 0.75, the higher this value was, the more difficult it was to get a high evaluatio n of the“ambiguity” and “low-contrast”. However, in the range where the average value of the rate ofchange was less than 0.75, the variance of these evaluations was large, and it indicated that
other factors might have strong influence on the evaluation of "gradation".
4. Conclusions and future works
It was found that the observed variables "ambiguity" and "low contrast" in "gradation", which
is one of the latent variables that explain the softness of light, was not highly evaluated when
the average value of the luminance change rate of the wall surface is high. There was a
possibility that "ambiguity" and "low contrast" were judged in other places in a room, therefore,
it is necessary to broaden the range of the investigation on the luminance gradient in theupcoming research. And further examination with other physical factors, such as edge
detection or spatial frequency analysis, would be also required to determine the "gradation"
evaluation when the average value of the luminance change rate of the wall surface is low. In
the future, we would like to find out the suitable physical variables which can estimate thesoftness of light through latent variables in the structural equations causal model.

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PO48
DEVELOPMENT OF NEW STANDARDS FOR MUSEUM LIGHTING
Alexandra A. Bartseva, Raisa I. Stolyarevskaya, Anna G. Shakhparunyants,
Anatoly Chernyak, Evgeniy Rozovskiy
All-Russian Scientific Research Lighting Institute named after S.I. Vavilov, RUSSIA
bartseva@vnisi.ru
Introduction
The new standards for museum lighting development was based on data collection by meansof questionnaires, processing and analysis of subjective assessments of art historians,
museum workers, research results of restorers and expert visito rs, along with objective,
physical measurements of photometric parameters of lighting installations in selectedexhibition halls of the most famous museums in Russia.
In early 2018, the Ministry of Culture of the Russian Federation initiated the study aimi ng at
development of up-to-date museum lighting requirements that museum employees may
adhere to in their work. One of the research directions of study was to obtain a complete
picture of the current state of museum lighting based on the results of polling and selective
monitoring of lighting parameters in a number of museums of Moscow, Saint Petersburg andothers cities.
The results of the survey revealed that many museums already use light -emitting diodes(LEDs) as light sources and are ready to completely switch to LED lighting. However, one of
the major problems, considered by museums, primarily small ones, is the lack of regulationsin the sphere of museum lighting.
Based on the studies performed, national standards of both a permanent and a prelimina ry
nature were prepared and introduced in 2020 by institute VNISI named after S.I. Vavilov.
Methodology
The methods of subjective research included a survey and questioning of museum staff direct organizers of various expositions, restorers, and engineer ing and technical personnel.
The main task was to collect and assess information on the state of museum lighting in the
country. The questionnaire, which was distributed among 168 museums of the RussianFederation of different levels and contained 13 questions regarding different aspects ofmuseum lighting, provided responses received from 90 museums, which allowed researches
to form the picture of the state of museum illumination in the Russian Federation [1].
Objective research methods included measurements of lighting parameters in several wellknown Russian museums (the State Hermitage Museum, St. Peteburg; the Tretyakov Gallery,
Moscow) [2]. When carrying out these measurements, it was revealed that there was a needto develop a more accurate and non-contact method for measuring the distribution ofillumination over the surface of paintings. For this purpose, the authors developed a special
method for measuring the illumination distribution of flat museum exhibits (paintings) in thevertical plane, based on the use of a luminance meter based CCD-camera (ILMD) and adiffuse reflecting screen. The method was tested and included as one of the measurement
methods in GOST 393-2020.
There was also an analysis of studies on the aging of materials, paints and wor ks of art
themselves, as well as analysis of the state of measuring instruments necessary for real
physical measurements of lighting parameters, the choice of these parameters, theirterminology and definitions, as well as methods of measurements, their pr ocedure andtechniques [3].

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Results
As a result of the conducted research, a group of standards was developed and approved at
the state level:
GOST R 58814-2020: National standard of Russian Federation “Museum lighting. Terms anddefinitions” ;GOST R 58815-2020: National standard of Russian Federation “Luminaire with LEDs formuseum lighting. General specifications”;
Preliminary GOST 392-2020: “Museum lighting. Lighting by LEDs. Requirements and Norms”;
Preliminary GOST 393-2020: “Museum Lighting. LEDs Lighting. Methods of Normative
Performance Measurements”.
Conclusion
For the first time in the past 30 years has issued national standards dedicated to museum
lighting, resulting from the joint work of the lighting and museum communities.
The presence of a set of lighting standards allowed the museum community to initiate work on
the creation of Uniform rules for organizing the acquisition, accounting, storage and use of
museum items and museum collections, which will allow the use of modern lighting standards
and requirements in practice in all museums of the country.

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PO49
SCALING OF SENSATIONS DURING THE PERFORMANCE OF VISUAL TASKS IN
RELATION TO HUMAN CENTRIC LIGHTING
Boos, G.V., Budak, V. P., Ilyina, E.I., Meshkova, T. V.
Moscow Power Engineering Institute, Moscow, RUSSIA
tvmesh@mail.ru

Abstract
The article deals with constructing a scale of visual perception, which is based on the spatial angular distribution of the luminance of carrying out simple visual tasks, such as reading asign and observing a picture. We propose a method for assessing the quality of lighting basedon the luminance spatial-angular distribution (LSAD), which allows us to model the luminanceat a point in the scene volume and formulate a new quality criterion.
1. Motivation, specific objective‘Human-centric lighting’ is the watchword of the time, which is not yet practical: we still know
little about the non-visual effect of light on an individual, we are aware of the visual effect, but
we do not know how to express it uniquely through the photometric characteristics of the lightfield.
A key task in computer graphics is to obtain a "realistic" image, and then there is a task ofcorrect calculation of illumination and luminance in lighting engineering. While the designer isguided by normative documents, defining qualitative and quantitative indicators of coverage.
In modern regulatory documents for non-special lighting installations, illuminance and various
parameters derived from it are normalized as quantitative characteristics. Howev er, theilluminance is an integral characteristic of the incident light, while the human eye reacts tolight reflected from the surface. From the point of view of the human eye, it is necessary tonormalize luminance. The current situation is quite understandable since the calculation andmeasurement of luminance were complicated until recently.
2. Methods
Currently, UGR is one of the main qualitative characteristics used in lighting design, which is
decided by the ratio of the total luminance of the source s in the field of view to the luminanceof the glare source. However, it only finds the level of discomfort from glare sources andallows you to predict the lighting installation's glare on the scale of discomfort.
At the same time, UGR does not consider the discomfort from specular reflections of sources.
In principle, it is possible to replace the reflected glare with fake sources with effective
parameters in lighting simulation. In the LSAD, discomfort is affected by the absolutemagnitude of the observed luminance and the ratio of the source-background luminancedifference to the background luminance (adaptation luminance). It is the contrast. The ratio ofcontrast to the threshold contrast can serve as a criterion for lighting quality. In the case of acontinuous LSAD over the lighting scene, like the allocation of fake sources, the naturalgeneralization of contrast is the average gradient ratio over the area to the threshold contrast.
The threshold contrast can be defined for each perception on the ps ychometric scale of visual
perception. An example of creating such a scale can be a system of five categories: ‘hardly
perceptible’, ‘comfortable’, ‘uncomfortable’, ‘unpleasant’, and ‘unbearable.’ A quantitative
representation of the visual perception scale can be derived from the hypothesis of a normal
distribution of ratings on the scale. Each stimulus generates many subjective estimates, but
for each interval on the scale, you can create a normal distribution with an average value anda standard deviation, where ‘hardly perceptible’ (the threshold for signal detection) and'unbearable' (pain threshold or threshold) are the upper and lower limits of the scale,respectively.

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3. Results
An experimental installation was created - a white square metal sheet (2 × 2) m2 on which
LED boards are mounted. An observer from 1.0 m looks at a colour palette measuring (12 × 8)
cm2, the center of which is located on the line of sight. The light source is located 10° above
the line of sight. The uniformity of the backgroun d is not lower than 0.7. The subject evaluates
the first feeling of luminance from a glare source with a gradual increase in luminance.
We plot the inverse function of the normal probability distribution for each category. On theabscissa axis, we will put the contrast on the axis of the ordinate-the probability of thesensation. Then the average values of contrasts for each category will correspond to theupper limits of the desired intervals of sensations with a probability of 0.5. The equal step inthe logarithmic scale and the almost parallel relationship obtained for the categories ‘hardly
perceptible’, ‘uncomfortable,’ ‘unpleasant’ and ‘unbearable’ shows the possibility of
constructing a numerical scale and deciding the intervals of subjective visual s ensations inunits of standard deviation. From this scale, the position of the category ‘comfortable’ isknocked out, which is since the understanding of the comfort of the lighting contrast varies
among observers and that this category does not obey the law of normal distribution since it
has the largest spread of values compared to other categories.
4. Conclusions
Thus, the resulting scale allows you to decide the threshold values of contrasts (upper bounds)[1,1; 6,2; 40; 113; 226] with a probability of 0.5 for five sensations when performing a simple
visual task for the source luminance in the range from 67 to 56000 cd/m2 and the backgroundluminance-from 128 to 190 cd/m2. This data is defined for a source located 10° above the lineof view. The threshold values for each sensation were obtained under the condition of a
uniform background, on which a single glare source is present, and for a simple visual task.
These values may be affected by an increase in background unevenness and a change in thetype of visual task since reading a sign differs from working conditions on a computer. To
decide the effect of the type of visual task and the background's uniformity, a separate
experiment is required. However, the resulting thresholds can be used as thresholds for
estimating the continuous LSAD across a lighting scene for a new quality criterion for simple
visual tasks, such as reading a sign or viewing the surroundings.

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PO50
ISSUES AND COUNTERPLAN OF EVACATION CENTER AT NIGHT- CASE STUDY OF NORTHEN GYMNASIUM IN SUZAKA CITY AFFECTED BY TYPHOONHAGIBIS IN 2019 1

Yamaguchi, H.1, Akizuki, Y.2, Shimojima, Y.3, Wakabayashi, N.4, Oe, Y.3, Yoshizawa, N.3
National Institute for Land and Infrastructure Management, Tsukuba, JAPAN, 2 Toyama
University, Toyama, JAPAN, 3 Tokyo University of Science, Noda, JAPAN, 4 Living
Environment Studio Act, Matsudo, JAPANyamaguchi-h92ta@mlit.go.jp

Abstract
1. Motivation, specific objective
Natural disasters, such as typhoons and earthquakes, are likely to occur in Japan bothclimatically and geographically, and the damage has become severe in recent years. In orderto survive from natural disasters, they may be forced to leave their homes and live inevacuation center that are not originally living spaces such as gymnasiums. The livin genvironment at the evacuation center is very important for ensuring the health, safety andsecurity of the refugees, but at present, preparations for providing a satisfactory living
environment are not enough. Since the Great Hanshin-Awaji Earthquake in 1995, there has
been a marked awareness of issues regarding the living environment of evacuation centers inJapan, and there is a gradual trend toward improvement in terms of living environment issues.
However, even in recent disasters that have passed more than 20 years, the same living
environment issues as at that time may be pointed out. This was considered to be afundamental problem due to insufficient accumulation and sharing of knowledge on themethods for improving the living environment of evacuat ion centers and their effects. For that
purpose, it is indispensable to develop a method that can evaluate the degree of living
environment of the evacuation center. In order to improve the living environment of theevacuation center, we have to consider various conditions, such as "ensure the lighting
environment for the safe and secure and sleep," "toilet ensure," "ensure the thermal
environment". In this study, we investigated lighting methods to prevent glare in the nighttime
lighting environment.
2. Survey of living environment for the evacuation centerIn this study, we first conducted an interview survey on the actual conditions and problems of
the living environment of the Northern Gymnasium in Suzaka City, which was used as a nevacuation center in Typhoon Hagibis 2019. From the results of the interviews, problems ofnighttime lighting environment were as follows; “blindfold was needed to sleep because ofglare light”, “it is too dark to walk when the lights off”.
Next, we reproduced the lighting environment when using the evacuation center andmeasured what the lighting environment was like at that time. We measured illuminancedistribution on the floor and the luminance distribution at several viewpoints. Among theabove problems, the glare index was calculated from the luminance distribution to understandthe current state of glare of night lighting that contributes to sleep disorders. The calculated
value of the glare index (UGR) was around 30, and it was confirmed as a numerical value thatlighting environment was glare and unpleasant.
3. Discussion of glare improvement methods at evacuation center
In order to examine an improve method for glare of the evacuation center, we set a lighting
plan by combining the luminaire output, lighting pattern and lighting method (direct / indirect).
We made a lighting simulation with Radiance to investigate the difference in the degree ofglare due to the lighting plan. As a result, it was shown that both thinning -out lighting anddimming luminaires are not always effective in suppressing glare. On the other hands, the257

CIE 2021 - Abstract Booklet

UGR value became around 10 when the walls were illuminated by using indirect lighting.
Therefore, indirect lighting method is effective to improve glare.
4. Conclusions
One of the problems with lighting in the living environment of evacuation shelters, the degreeof glare that contributes to sleep disorders was clarified from actual measurement surveys.
Regarding the glare improvement method, the effectiveness of indirect lighting was shown
based on the results of brightness distribution simulation with Radiance. Natural disasters
could occur, of course, in various parts of the world, and organizing methods for improving
living environment of the evacuation center is extremely useful not only in Japan but also in
the world. It is necessary to continue to accumulate knowledge.

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PO51
COMPARING THE PRIVACY VS DAYLIGHT COMPROMISE FOR DIFFERENT WINDOW
COVERINGS
Hussain, I., Fotios, S.
University of Sheffield, Sheffied, UNITED KINGDOM
steve.fotios@sheffield.ac.uk

Abstract
1. Motivation
Cultural factors in Libya (and other Muslim countries) require female privacy to be maintained.
Outside the home, females must wear clothing that reveals only the face and hands. Wheninside the home and located near windows, a similar degree of clothing cover, or, window
screening, is required. This reduces exposure to natural daylight, with resultant reduction in
health benefits of daylight. This could be alleviated using window design, which optimizes theprivacy vs daylight transmission trade-off and allows females to wear relaxed clothing when athome
2. Methods
Two privacy devices have been considered, horizontal blinds and frosted glass. For blinds,
free area (i.e. proportion of glazed area not obscured by the blinds) was t he independent
variable, with six levels ranging from 3% to 60%. For frosted glass, the independent variable
was the degree of frosting, simulated using the distortion filter in Photoshop, with five levels
ranging from 4 to 20.
The degree of privacy offered was operationalized by identification of the clothing level wornby a target behind the window screen: there were seven levels of clothing (characterized byamount of skin exposure and clothing tightness), a novel scale developed in preliminary work.
Two test procedures were used: (1) categorical rating of separately evaluated images,
categorizing the observed clothing level to the clothing scale, (2) a paired comparison (allpossible pairs) with the task to identify “in which side is the target wearing m ore clothing”. Nullcondition trials and counter balancing were included.
3. Results
Experiments using the blinds are completed. Responses from the 40 test participantsrevealed that the free area must be reduced to 3% (i.e. almost fully closed) to ensure that it is
not possible to identify the amount of clothing worn. It is not anticipated that this would be a
sufficient trade-off for relaxed clothing, but this will be confirmed by daylight simulation.
Experiments using the frosted glass are on-going. Results to-date suggest acceptable privacy
can be achieved whilst maintaining a greater amount of daylight than with blinds.

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PO52
EVIDENCE-BASED RESEARCH AND APPLICATIONS FOR HEALTH LIGHTING DESIGNIN UNIVERSITY CLASSROOMS
Wang, T.Y., Hao, L.X.
College of Architecture and Urban Planning, Tongji University, Shanghai, CHINA
1810123@tongji.edu.cn

Abstract
1. Motivation
Classroom is an important place for students to learn and grow up. Students usually spend
about 8~10 hours in the classroom every day. Bad classroom light environment will affect theworking state and development of students' visual system. In addition to the immediate
damage, such as fatigue and cognitive decline, there is a cumulative effect in the long term,such as poor vision, sleep disturbances, depression and poor academic performance. In orderto improve the current situation of classroom lighting, it is necessary to conduct evidence based research and targeted lighting design according to the existing problems of classroom
lighting environment and the use needs of students, and observe the changes of students'
subjective evaluation and emotional state.
2. Methods
Before the renovation of classroom lighting, light environmental parameters were measured intypical classrooms at night to understand the uniformity of horizontal illumination on thedesktop, colour temperature, colour rendering and maintenance status of lamps. Interviews
and questionnaires were conducted for students who have been using these classrooms for along time to understand their current evaluation and subjective preferences on classroom
lighting. Through the design of lighting lamps to improve visual efficiency and adapt to thehealth needs of teenagers, a new type of classroom lamps with upper and lower light emi tting
mode is developed, which makes the light distribution in the classroom more reasonable andthe illumination on the desktop significantly improved and more uniform. Luminaires with acolour temperature of 5000K were selected, and the average colour re actance index Rareached more than 90. One year after the renovation of classroom lighting, fieldmeasurements and interviews were conducted on the classroom light environment again in
December. A total of 41 valid questionnaires were collected to revaluat e the subjective
satisfaction, sleep and emotional self-evaluation of the light environment in the classroom.
3. Results
Through the measurement of light environment in the college classrooms before therenovation, it was found that the illumination defici ent (273.7 lx desktop horizontal
illuminance), colour temperature on the high side (close to 7000 k), the illumination uniformityof desktop (0.5) and colour rendering index (Ra = 74) on the low side, the glare of lamps andlanterns, damage and lack of maintenance and other issues. Through questionnaire survey
and interview among college students who usually stayed in these classrooms, it was foundthat 54.3% of the students thought that the light environment of the classroom was too dark,
60.1% of them thought that the light colour of the classroom was too cold and white, 54.29%
of them hoped to use yellow and white light, but not warm yellow light (only 8.57%), 51.43% ofthem thought that the light environment of the classroom was uneven. Therefore, it wasnecessary to use lamps with lower colour temperature, change the number and arrangementof lamps and lanterns, and improve the illuminance and evenness level of the working face.
After the renovation was completed, the post-use assessment of the classroom was carriedout again, and the results showed that the students' evaluation of the brightness of theclassroom changed from 48.57% slightly dark to 90.24% moderate after the reconstruction,and the illumination level of the working face was significantly improved (the horizontal
illumination of the desktop was 607.4lx).The evaluation of light colour changed from 17.14%

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too cold white and 42.86% slightly cold white to 73.17% moderate. The evaluation of desktop
evenness changed from 51.43% relatively unevenness to 7.32% relatively unevenness(evenness is 0.9). The overall satisfaction degree of lighting was significantly improved. On
the basis of visual function evaluation, the students' sleep and emotional state were evaluatedsubjectively. The self-evaluation of sleep quality improved overall, while the change of sleep
time was not obvious. However, the score of the students' Self -rating depression scale (SDS)
was significantly reduced, and the average score was reduced from 34.66 to 29.28, indicatingthat their depression mood was somewhat relieved.
4. Conclusions
The design of indirect light emitting lamps is conducive to improving the overall visual comfort
and uniformity of the desktop. It is not recommended to use lamps with too high colour
temperature in the classroom and warm white light is more appropriate. Light environment
with high illumination level in the daytime has a positive effect on students' sleep and canrelieve their depression.

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PO53
FIELD SURVEY ON LIGHTING ENVIRONMENT FOR WORK FROM HOME IN JAPAN
Mochizuki, Etsuko, Kurumi NagasakiJAPAN
etsuko.mochizuki@p.chibakoudai.jp

Abstract
1. Motivation
In 2020, COVID-19 has been spread worldwide and that changed the lifestyle of generalpublic in many aspects. Japanese government announced a state of emergency for 7
prefectures (Tokyo, Kanagawa, Saitama, Chiba, Osaka, Hyogo and Fukuoka) on April 7th,
2020, which was extended nationwide on April 16th, 2020. The state of emergency wasphased out during May 14th and 25th, 2020.
Under the state of emergency, going outside was restricted except in the case with urgent
purpose. For office workers, it was recommended to work from home. In Japan, the working
environment in office is regulated based on the Ordinance on Health Standards in Office.
However, the working environment in home quite differs from that in office. In general, lighting
environment, furniture, atmosphere and etc. in any location at home are not designed aiming
at working and those might cause fatigue and stresses in workers.
The purpose of this study is to identify the actual situations of the environment for work fromhome in Japan. This paper reports the results of the survey comparing the working
environment in home with that in office.
2. Methods
2.1 Questionnaire survey
Questionnaire survey was conducted for the working adults who worked in the same officemore than three months. 57 answers were obtained during June, 2020. About 90% of the
respondents lived in Kanto region and about 60% of the respondents commuted to Tokyo
before the coronavirus emergency.
In the questionnaire, the following items were asked.
 From when was work from home requested?
 Working days per week and working hours per day in office/ at home
 Commuting time to the office The reasons for choosing the work location at home
 Window size, space size of the work location at home Working efficiency, sleepiness during work, fatigue, motivation, communication withcolleagues in the case of work from home
 Awakening and falling asleep, mental health during work from home
2.2 Measurement of the environment for work from home
Field measurements of the work location at home were conducted in two seasons, between
August and October as the summer season and between November and December as thewinter season. The measurements were taken by the respondents who agreed to themeasurement in the questionnaire. In the summer season, the measurement was conductedby 17 different respondents and in the winter season, the measurement was conducted by 13
different respondents.

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Air temperature, relative humidity, horizontal illuminance on the desk and vertical illuminanceat the eyes (T & D TR-74Ui) at intervals of 1 minute, and air velocity (CUSTOM AHLT -102SD)
at intervals of 2 minutes were measured during working hours for 2 days each in home and in
office. Each measurement equipment was settled within 0.5 m from the sitting place.
The respondents were asked to evaluate brightness on the desk, spatial brightness, thermal
environment, acoustic environment, working efficiency, fatigue and satisf action as working
environment at every three hours during the measurement.
3. Results
3.1 Comparison of the working situation in office and at home
The percentage of the respondents who worked for more than 49 hours per week, long hours
working, was halved under the state of coronavirus emergency, from 15% in office to 7% at
home. On the other hand, there was a worker who worked for more than 90 hours, 7 days aweek.
During work from home, almost of the all respondents used PC monitors for most of their wor k,
though when working in office about 42% of the respondents used PC monitors for less than
70% of their work.
3.2 Fatigue and working efficiency during work from home
The commuting time to office including on foot, by bus and by train and etc. was 60 to 70
minutes in average and 120 minutes at maximum when working in office. However, the feelingof fatigue was not reduced during work from home even without commuting.
More than 75% of the respondents worked from home for more than 8 weeks and about 5%
for 16 weeks when they answered the questionnaire. There was a tendency that the
respondents felt more fatigue as the period for work from home became longer. It was also
identified that the working efficiency became lower with the respondents who worked for m ore
than 49 hours per week at home. However, the number of the respondents whose working
efficiency became lower was reduced and that became higher was increased as the period forwork from home became longer than 10 weeks. The respondents might get used t o thesituation after 10 weeks' work from home. It was also identified that the working efficiency andmotivation were strongly effected by physical and mental health, such as fatigue, awakening
and falling asleep and etc., with the respondents who worked from home for less than 10
weeks.
3.3 Lighting environment in the work location at home
The total luminous flux density in the offices was about twice of that in the work locations athome – 1015 lm/m2 in office in average and 530 lm/m2 in home in average. The correlated
colour temperature of the luminaires settled in the almost all office was daylight colour, 5000K.
And it was the same for the most of the work locations at home. The area of windows was
relatively larger in the work locations at home than in the offices.
The percentage of dissatisfied for the working environment at home was higher in the cases
when the luminaires were turned on than in the cases when turned off both in the summer
season and in the winter season. The measurement results also indicated that the
respondents were dissatisfied for the working environment when the vertical illuminance attheir eyes was higher than the horizontal illuminance on the desk with low level.
4. Conclusions
More information and data on the working environment at home should be collected andanalysed to identify the suitable lighting environment for work from home.

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PO54
TEST TO ASSESS THE ACCURACY OF THE LIGHTING COMPUTER SOFTWARE WHEN
DESIGNING ROOMS WITH WINDOWS
1

Dubnicka, R.1, Mokran M.1, Raditschova, J.1, Gasparovsky, D.1
Department of Electrical Power Engineering, Faculty of Electrical Engineering andInformation Technology, Slovak University of Technology, Bratislava, SLOVAKIA
roman.dubnicka@stuba.sk

Abstract
1. Motivation, specific objective
In the current architecture of buildings, window glass glazing plays an important role to haveensured sufficient daylight access. A large amount of artificial light comes out from thebuildings through the windows or other daylight openings, especially in the case of glass
corridors or offices, which may have several glass walls which is at present very often
practiced in building engineering of administrative properties. The accuracy of the lighting
calculation of photometric parameters of indoor workplaces is of great importance because
cumulative errors can become serious differences between calculated photometric parametersin comparison with the real parameters investigated and evaluated by the field measurement
after mounting of the lighting system. An acceptable error for individual input parameters canlead to a totally unacceptable error at design level which in practice is hard to correct for thewhole lighting system due to the electrical leads being designed in project documentation.
Therefore adding other luminaires because of underestimation of these errors can be asource of unplanned investment. This motivation for greater accuracy of calculations oflighting system parameters are the investor's demands for efficient operation of the lighting
system and energy efficiency of buildings at certification of buildings. Even more the accuracyof the lighting calculation and the lighting calculation tool used can affect competitive tenders.
In the absence of the most accurate calculations, it is not po ssible to make a satisfactoryjudgment of indoor workplace lighting systems. The one of the errors is that the designer does
not consider the glazing of openings of the room and therefore simplifies the calculation not todesign openings in the model of the room. The second error can be caused by a calculation
algorithm that is not completely accurate when the transmission of light through objects is set
as input parameters of openings in lighting calculation tools used for computing photometricparameters of lighting systems of indoor workplaces. Both cases of error mentioned above
are described in this article. These errors were proved by research work when calculation andthe field measurement were performed of the various indoor workplaces with windows a nd
glazing openings. This paper deals with errors occurring using various lighting calculation
tools broadly used by lighting engineers at designing by comparison of calculated results ofphotometric parameters according to requirements of relevant standar ds for indoor
workplaces.
2. Methods
Comparison of calculation tools shall prove the integrity between results calculated by various
lighting calculation software used by lighting engineers in practice. The document CIE No.
171:2006 describes methodology about required comparison and state benchmarking if theresults are comparable in calculation software to each other. In the research work were usedvarious lighting calculation tools using different calculation approaches to compare results
assuming indoor workplace with glazing openings e.g. windows, glass walls etc. for possible
errors which can occur at the lighting calculation process. Position of glazing openings andgeometry of indoor workplaces at research was different to show possible errors which canoccur. Validation of these results was performed by field measurement of the particular indoor
workplace under investigation.

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3. Results
Based on the results of using various lighting calculation tools in the research work for chosenindoor workplace examples with glazing openings, photometric parameters required byrelevant standards were compared and evaluated according to document CIE No. 171:2006.
Even more, the field measurement of indoor workplace finds possible errors between
calculation and reference parameters obtained by measurement with assumption of
uncertainty of measurement estimated according to the GUM document.
4. Conclusions
In the lighting calculation process of the photometric parameters of the lighting system
according to relevant standards, several errors can occur related to the glazing of windows
and openings of the particular indoor workplace. This paper reveals problems at the design ofindoor workplaces with models of glazing openings in the room by using various lighting
calculating tools. Based on the results presented in the paper can be used for prediction andavoiding these errors in the practice as help for lighting engineers. Furthermore it can bestated some tolerance interval which shall be assumed at various cases in t he practice.

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PO55
COLOUR & LIGHT DESIGN: AMBIENCE AS AN ANSWER TO THE PROBLEMS OF AHEALTHY COLLECTIVE HOUSING.
1

Caumon, L.1,2,3, Zissis, G.1, Caumon, C.2 , Bécheras E.2, Christelle, I.3
LAPLACE, UMR5213 (CNRS, INPT, UT3), University of Paul Sabat ier, Toulouse, FRANCE,2
LARA SEPPIA, EA 4154 (UT2J), University of Jean Jaures, Toulouse, FRANCE3
SOBRIM Company - HARANAM concept, Bayonne, FRANCE
Corresponding author: lorrain.caumon@laplace.univ-tlse.fr.

Abstract
1. Motivation, specific objective
Health and housing are two of the most important and necessary concerns for the quality ofhuman’s life.
In a post-health crisis context, confinement periods have shown that the comfort of housing
have a proven impact on the quality of life and well-being of its occupants.
Although they have been at the heart of many discussions in recent years, these problematics
are all the more topical and encourage a great deal of research in the tertiary sector and areinevitably gaining ground in the field of real estate development and collective housing.
The notion of life quality often translates into the ambition to build responsible buildings.
Today, increasingly real estate developers have become aware of these new demands andare keen to put human concerns back at the heart of health and building issues. For this, they
include well-being in a scientific approach. Underpinned by standards, measurements, andanalytical results, these approaches contribute to a better life quality, by respecting theinterrelationship between living beings and their daily environment.
Regarding the visual ambience; we know that 80% of the information that comes to us fromthe outside world is transmitted through our eyes, which is why light and colour are theessential materials for the positive and stimulating perception of our life places.
Consequently, we can affirm that the conception of chromatic and luminous environments, aswell as, the air, water and other qualities of intrinsic characteristics of housing, contributeequally to meet the users’ expectations in terms of health and life experience, both in thecontext of individual housing and collective residences. In this way, it’s essential to take into
consideration the needs of each person for visual comfort, security sensation, but also theatmosphere of the place.
2. Methods
The study presents a protocol combining colour expertise (colour countertypes) and lighting
expertise (light characterization) in order to conceive a visual environment adapted to theusers’ needs (reference observer), but also the characteristics of the place where the project
is located.
The colours chromatic countertypes are produced with the NCS (system of natural colours)
tools and are associated with a photometric study in order to character ize a visualenvironment. These investigations and analyses have been carried out in several collect ive
residences (Basque Country, France).
These residences have commonality features, it has been built over the past ten years, it islocated in a relatively similar landscape context and it is accommodating approximately thesame number and inhabitants’ types. Also, this study mainly focuses on common spaces andinterior horizontal circulations. We know that it is essential to attach more and more
importance to the visual ambiances of entrance halls and interior passages. These places

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must create a welcome feeling, a visual comfort and safety for all users, at all ages, day andnight.
Therefore, the method used must be able to prove the coherence and harmony of the exteriorlandscape treatments with the chromatic and interior lighting treatments in order to reinforce a
better well-being feeling, while ensuring visual continuity of the living spaces between theexterior and interior.
3. Results
These data allow to establish the methods for drawing up a protocol conception of chromatic
ranges and lighting design applied on the collective residences’ environment in order toevaluate the habitat influence on the life quality.
Initially, the results of these data served as a state of the art in terms of standards and design
applied to collective residences built over the last decade.
Secondly, the data served as a basis for comparison and allowed us to establish criteria of
success in terms of visual ambience within existing buildings.
The purpose of this protocol in research-creation, around the study of excitement will be topresent, in a second step, a comparative study between these residences and those on
construction. This comparative study will complement the research protocol studied in thisarticle, in order to allow us very soon to design visual atmosphere s more adapted to humanphysiological needs and to prove the merits of qualitative approaches in terms of light andcolour design within the new real estate programs initiated by the developer.
4. Conclusions
In conclusion, this protocol will help the property developer to gradually move towards a moresensitive and thoughtful design around lighting (natural/artificial) and colour applied in theresidential sector. Capturing visual harmony, from the outside to the inside, today allows
residents to free themselves from the usual patterns of poorly treated lighting environments,
too often generating neutral, standard or anxiety-provoking spaces.
This protocol must offer different, enhanced outdoor/indoor spaces that are more adapted to
the needs of all age groups of residents. Given the health context in which we find ourselves,
and where expectations towards real estate projects are always more ambitious, it is essential
to perpetuate this type of protocol so that the actors of real estate development continu e to be
fully aware of the expectations and permanent evolution of this society by placing humanneeds at the heart of their research and creations.

Keywords: Lighting Design, Colour-Design, Care-Design, Standards, In-Situ Observation.

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PO56
INTEGRATION OF DAYLIGHT WITH ELECTRIC LIGHTING IN COMMERCIAL
BUILDINGS: A CASE STUDY FROM NEPAL
Banjara O.S.1, Bista D.2,3
Department of Mechanical Engineering, Kathmandu University, 45200 Dhulikhel, NEPAL
2
Department of Electrical and Electronics Engineering, Kathm andu University, 45200
Dhulikhel, NEPAL
3
Center for Electric Power Engineering (CEPE), Kathmandu University, 45200 Dhulikhel,
NEPALom.banjara@student.ku.edu.np

1

Abstract
1. Motivation, specific objective
Nearly 24.1% of grid electricity is consumed by lighting, which is the highest energy
consumption sector in buildings of Nepal. An average of 4.5 hours of a sunshine period isrecorded daily throughout the year in Nepal. However, integrating this natural light in abuilding has not yet been studied or considered during lighting design practices. The conceptof daylighting is to permit the natural light inside a building with an aim to increase its
illumination level and visual comfort. The incorporation o f daylight in a building could greatly
aid in reducing the energy consumption due to artificial lighting. In this study energy efficient
lighting system was designed to integrate daylight for a commercial building in context of
Nepal that can function on minimum external energy resources for lighting purposes.
2. Methods
A multipurpose hall facing north alignment 270° of (longitude 85.53° and latitude 27.62°) was
taken for the study. The 3D model of the building was constructed and simulated in DIALux
and the simulated data was validated on-site. First, the light-emitting diode (LED) artificial
lighting was simulated followed by a series of daylight simulations under settings of threedifferent sky type models: clear, average, and overcast sky with direct su nlight throughout theyear. Again, the simulations were carried out applying façade elements and adding building
openings to increase or decrease the illumination level wherever required. Finally, all the data
were analyzed and compared by integrating artificial and natural daylight in the building for
determining energy saving and lighting cost.
3. Results
The overall study in the selected building showed that by integrating daylight with artificial
light saves energy by 75% at clear sky, 50% at average sk y and 20% at overcast sky
condition. The cost of the electric lighting was also reduced by 20 -75%.
4. Conclusions
Hence, integrating daylight during lighting design increases the illumination level, thusincreasing the visual comfort inside the building. Manual and automatic Light controlling
strategies could be used to control artificial lights with respect to the daylight for a more
efficient system. If the design decisions can be made in the very early stage of building
construction, it will have a significant impact on the overall energy consumption and theinternal environment of the building.
Keywords: daylighting, energy efficient lighting, lighting design, energy efficient buildings

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PO57
TOWARDS AN IMPROVED V‐VLC OPTICAL CHANNEL MODELLING
Dotreppe, G.M.1, Coosemans, J.M.1, Jacobs, V.A.1
Vrije Universiteit Brussel, Brussels, BELGIUM
Guillaume.mario.dotreppe@vub.be, jan.matei.coosemans@vub.be, valery.ann.jacobs@vub.be1

Abstract
1. Motivation, specific objective
While a decreasing trend in road mortality is observed, road accidents are still the leading
cause of death amongst young people (aged between 15 and 29 years) and the 8 th leading
cause of death globally. Hence improving the road safety is of uttermost importance. Amongst
others, this problem can be tackled by increasing the advanced driver aid systems (ADAS)
and the autonomous vehicle (AV) integration in the vehicle fleet. For these technologies tobecome mainstream, communication capabilities among vehicles themselves (V2V) andbetween vehicles and infrastructure (V2I) need to improved. Presently used communication
technologies, employing radio frequencies (RF), show several problems:
1. High latency and low data throughput
2. Low efficiency
3. Limited penetration in underground roads
4. High interference in crowded urban scenarios
These aspects can be improved upon by making use of vehicular visible light communication(V-VLC). V-VLC has recently gained a lot of interest amongst the automotive community tointegrate it within the Intelligent Transportation Systems (ITS). This technology employs thevisible part of the electromagnetic spectrum to transmit data. It provides a high bandwidth,
high efficiency, low latency and free of electromagnetic interference communication.
Additional advantages include the fact that it employs a license free band, as opposed to the
RF spectrum, and is safe for the human health.
Nevertheless, V-VLC cannot be used as the unique communication method due to the limited
real world range, its line-of-sight nature and the influence of the atmospheric attenuation. The
latter has been widely studied in meteorology. However, traditionally, a human observer wasconsidered when investigating the effects of the atmosphere and adverse weather conditions
on the propagation of light. In the case of V-VLC, the systems is composed of a transmitter
receiver combination employing LEDs as light source and photo diodes (PDs) as receivers.
Hence, the effects of replacing a human observer by an optical sensor shall be investigated.
This will allow to evaluate the behaviour of V-VLC in adverse weather conditions, which is
required before it could become a worthy alternative to traditional RF communication methods
for automotive applications. Having a detailed optical channel model is needed to create an
optimized system. Depending on the extent of the differen t influences (atmosphericattenuation, geometric misalignment, etc.) the number of sensors, their position andorientation shall be adapted. Furthermore, the potential of using different sensor types withdifferent spectral sensitivities and responsivity s hall be investigated.
This study serves as a starting point, where the influence of fog on the light propagation will
be investigated theoretically and compared to the results of ray tracing simulations. Light
scattering and geometrical losses due to misalignment of the transmitter and receiver pair will
be included as a first step towards the V-VLC integration. A first V-VLC performanceassessment will include the determination of the bit error rate (BER), signal to noise ratio(SNR) and channel impulse response (CIR).

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2. Methods
As mentioned in the first section, this study will investigate the influence of fog on the opticalchannel theoretically, based on simulations and in a later phase experimentally. Based on its
properties, also different types of fog will be considered. All these observations shall becompared to draw relevant conclusions.
For the theoretical analysis, the Mie theory will be applied to account for the scattering effectof small spherical particles in the optical channel. This will allow us to compute the extinction
coefficient of the atmosphere which will then be utilized in Lambert’s law for the illumination
by a light source in combination of the Bouguer’s law of atmospheric attenuation.
These computations will be compared to empirical models (e.g. Kim’s model) used to estimate
the extinction coefficient based on visibility measurements.
Finally, ray tracing simulations will be performed and the obtained results will be comparedagainst the former theoretical solutions.
3. Results
At the time of writing, the study is still ongoing. Hence, no results can be published or
discussed yet.
4. Conclusions
Similarly to the statement made in section 3, no real conclusions can yet be drawn.
Nevertheless, based on an extensive literature review, a hypothesis can be given. It is
expected that with increasing fog thickness and distance between emitter and receiver thesignal strength will decrease. This will influence performance indicators such as the BER,
SNR and CIR. Furthermore, often omitted in meteorological studies, the sensor misalignment
will induce a strong loss in received optical power. Including this term is important for avehicular application due to the dynamic conditions, e.g. varying sensor height based on thevehicle’s design, road irregularities inducing relative motion between transmitter and receiver,vehicle movement including lane switching, etc.
Nevertheless, the study will point out the extent of the different influence. Future experimental
validations will then either confirm or reject the observations. Based on this, the subsequentactions will be determined.

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PO59
A LABORATORY STUDY ON VISUAL AND EMOTIONAL COMFORT EVALUATION OF
LED WIDE BEAM ANGLE LAMPS : TAKING 3000K/ 4000K / 5000 K LINEAR LAMPS AS
RESEARCH OBJECT *Feng, K., Hao, L.X., Dai, S.J.
Tongji University, Shanghai, CHINA
ciochie@163.com

Abstract
1. Motivation, specific objective
LED wide beam angle lamps have been widely used (such as media façade lighting) which
provide much more diversity and flexibility for nightscape performance than traditional
floodlighting lamps. But it should be recognized that light emitted by these lamps entered theurban environment directly without comprehensive consideration, which might leading to glare
or light pollution easily. It’s been well known that lights at night (LAN) has negati ve impacts onhuman eyes, emotions and circadian, but standards nowadays are mainly for traditional
lighting products while requirements for wide beam angle products is far from enough, which
results in a lack of principles in design procedure and scientific standards for managers.
A laboratory experiment was carried out in which visual and emotional comfort wasconsidered as evaluation items. We selected 3 linear lamps (including 3000K / 4000K / 5000K)
which are widely used in cities, to evaluate emotional and visual comfort changes made bydifferent brightness or dynamic speed, and the comfort threshold in each scenes werediscussed, which would both provide scientific support for similar research in the future.
2. Methods
The experimental installation included the light-emitting board and the observation box.
3 lamps were used including 3000K / 4000K / 5000K, beam angle 120 °which were commonlyused in cities (especially in media façade lighting situations).
The static state includes 5 brightness levels realized by controlling the output power of lamps(20% / 40% / 60% / 80% / 100%). Dynamic state includes erasure and shading, each includes
five playback cycles, 2s / 4s / 6s / 8s / 10s (commonly used in cities).
Both visual and emotional comfort evaluation include 7 items, and each item would be valued
through -3 to 3, to express severe discomfort (-3) to very comfortable(3).
In the experiment stage, subjects were asked to watch different lighting scene for 1 minute,after which experimenters would ask questionnaire about eye comfort and emotional comfort
and 630 results have be received per subject (20 subjects in total).
Median and mode number were used to evaluate features and changing trends of visual andemotional comfort.
3. Results(1) Static scene:
Eye comfort evaluation: With the increase of brightness level, the frequency of negativeevaluation (-1/-2/-3) is increasing. The median number of 3 lamps (5000K/4000K/3000K)
changes to -1 (slight discomfort) at 80% brightness, and the median number of 500 0K
changes to -2 (moderate discomfort) at 100% brightness, indicating that the degree of
discomfort enhanced. The mode number of 3 lamps changes to -1 at 80% brightness, and thedata of 3000K and 5000K changes to -3 (serious discomfort) at 100% brightness level.

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meanwhile, some subjects （ 4/20 in 3000K; 4/20 in 4000K; 4/20 in 5000K) think thatbrightness in lower level (mainly focused on 20%/40% brightness) will also cause discomfort.
Emotional comfort evaluation: The median number of 3 lamps changes to -1 at 100%brightness; The mode number of 4000K changes to -1 at 100% brightness while 3000K /5000K showed 0 (no feeling). At the same time, some subjects （5/20 in 3000K; 4/20 in 4000K;
6/20 in 5000K) think that brightness in lower level (mainly focused on 20% brightness) will
also cause discomfort.
(2) Shading scene:
Eye comfort evaluation: With the lighting period shortens (i.e. the lighting changing speed
becomes faster) from 10s to 2s, the median number of 3000K changes to -1 at the level of 4s(no further change at 2s) while 4000K/5000K changes at 6s, and continue to change to -2 at
2s. The mode number of 3 lamps showed a same result as median number. meanwhile, somesubjects（8/20 in 3000K; 6/20 in 4000K; 5/20 in 5000K) think that lower speed (mostly at 10s)
will also cause discomfort and expressed a preference to 4s/6s separately.
Emotional comfort evaluation: The median number of 3 lamps changes to -1 at 2s (fastest
level); The mode number of 4000K changes to -1 at 2s while 3000K/5000K keeps 0 in all
situations. Meanwhile, some part of the subjects （ 8/20 in 3000K; 7/20 in 4000K; 7/20 in
5000K) think that lower speed (mostly at 10s) will also cause discomfort and expressed apreference to 4s/6s/8s separately.
(3) erasure scene:
Eye comfort evaluation: With the lighting period changing from 10s to 2s, the median numberof 3000K changes to -1 at 2s while 4000K/5000K changes at 4s. The mode number of 3 lamps
showed a same result as median number. Familiar with shading scene, 8/20 in 3000K, 6/20 in
4000K, 5/20 in 5000K subjects think that lower speed (mostly at 10s) will also cause
discomfort and expressed a preference to 4s/6s/8s separately.
Emotional comfort evaluation: The median number of 3 lamps changes to -1 at 2s; The mode
number of 4000K changes to -1 at 2s while 3000K/5000K keeps the number of 0. meanwhile,
8/20 in 3000K, 5/20 in 4000K, 8/20 in 5000K subjects think that lower speed (mostly at 10s)
will also cause discomfort and expressed a preference to 4s/6s/8s separately.
4. Conclusions
Both brightness and dynamic speed could lead to people’s negative emotions and eye
discomfort. In most cases there’s a time delay between emotion and eye data, emotional
discomfort always occurs behind the eye’s discomfort (needs a higher stimulus);
The comfort evaluation of different brightness levels shows the overall characteristic that ahigher brightness could leading to more negative evaluations, but to some people, medium
brightness gives a more comfort feeling;
A faster speed leads to more negative evaluation, but some subjects prefer a medium speed(both in shading and erasure situations);
According to conclusions above, further research should be done to value different lamps
including other colours, so as to give a better support for wide beam angle lamps’ use in cities
both for designers and managers.

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PO60
THE IMPACT OF COLOURFUL AND DYNAMIC LED MEDIA FAÇADES AND
BILLBOARDS ON ASTRONOMICAL OBSERVATIONSSteve Lau, Christopher Kyba, Richard J. Wainscoat
Institute of Intelligent Lighting, Hangzhou YD Illumination Co. Ltd, CHINAGFZ German Research Center, GERMANY
University of Hawaii, Institute for Astronomy, USA
Stevelau@china-yd.com

Abstract
More and more LED media façades and LED billboards are being installed on architecture andbuildings in order to decorate city skylines or to deliver advertisements. The shopping malls inthe busiest streets in city centers make extensive use of LEDs to attract tourists and topromote the nighttime economy and business. In order to achieve the desired graphic and thedisplay needed, these LED media façades and LED billboards utilize RGB LEDs or RBG whiteLEDs and a control system which emits a wide spectrum of light, including blue, green andred light. Although each of these colours contributes to skyglow via Rayleigh scattering, bluer
colours of light are more efficiently scattered, and are of particular concern. The shift of theusage of conventional light sources like incandescent lamp, low p ressure sodium and highpressure sodium light sources to this new type of colourful and dynamic LED media façade
and billboards has brought new challenges to astronomers. This paper describes how the lightemission from LED media façades and LED billboards increases the artificial skyglow in theatmosphere and more importantly how this brightening skyglow affects astronomical
observations.

Keywords: LED media façade, LED billboards, skyglow, Rayleigh scattering, artificial skyglow,
astronomical observations.

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PO62
A REVIEW OF THE IMPACT OF LIGHT POLLUTION ON ECOSYSTEMS AND SKY
BRIGHTNESS
Jägerbrand, A.K.1, Nilsson Tengelin, M.2, Durmus, D.3
Halmstad University, School of Business, Engineering and Science, Department ofEnvironmental and Biosciences, Rydberg Laboratory of Applied Sciences (RLAS), Halmstad,
SWEDEN, 2 Department of Measurement Science and Technology, RISE Research Institutesof Sweden, Borås, SWEDEN, 3 Department of Architectural Engineering, Pennsylvania State
University, USA
annika.jagerbrand@hh.se
1

Abstract
1. Motivation, specific objective
Sustainable outdoor lighting should fulfil the functional needs of the users, be cost - andenergy-efficient, and result in minimal environmental impact. Despite the transition to theenergy-efficient light-emitting diode (LED) light sources, the outdoor lighting consumes alarge amount of energy. Public lighting is used on roads at night to create traffic safety, asense of security, and to provide important benefits for humans. Buildings and works of art
are often illuminated for aesthetic or cultural reasons to improve the social sustainability ofcities or areas.
Despite the need for light at night, there might be negative consequences of electric lightoutdoors at night, such as: (i) unwanted ecological impacts on animal species and otherorganisms, (ii) disrupting the observations of the night sky, and (iii) negative impacts tohuman observers through glare, intrusive lighting, and potential adverse health effects.
Light pollution is generally considered unnecessary energy waste, and it can have negativeenvironmental impacts when light is spread into the environmental surroundings and/or
scattered in the atmosphere without a function and can also cause harmful effects. Light
pollution should therefore be reduced or eliminated for the outdoor lighting to be sustainable.
The objectives of this study are to present the state-of-the-art research performed in the light
pollution research field with a focus on ecosystems and sky brightness, to report on evidenc ebased impacts, and evaluate methods used in the studies.
2. Methods
A literature review was performed by analyzing light pollution studies found in scientific
databases, such as Scopus. We used search terms for light pollution (e.g. artificial light atnight, obtrusive light, light pollution, light trespass, skyglow), and identified relevant studies inthe two topical areas (i.e. ecosystems and sky brightness). The studies were filtered byscanning the titles, abstracts, and applying exclusion and inclus ion criteria. Only papers
written in English that are published in peer-reviewed journals have been analyzed. Other
exclusion criteria included lack of measurements, background/literature review papers,
studies conducted in indoor environments, and studies that solely utilize natural light (e.g.
moon light).
3. Results
Our investigation underlined the recent trend in the increase of publications in the field of light
pollution during the latest 5-10 years. Although the fields of astronomy and sky brightnes s
have a long tradition of research in this area, investigations of the impacts of light pollution on
ecosystems has only recently gathered more attention. For sky brightness, it is common touse satellite-based measurements, as well as sky quality meters (SQM), RGB cameras,
computational models or simulations for quantifications of the brightness. Ecosystem studies
have focused on field observations in combination with experimental changes of road lighting
on various species or groups of species (e.g. bats , birds, and insects) that are expected to be274

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particularly sensitive to light due to positive or negative phototaxis. Experiments conducted in
the field, “simulating” road lighting or road lighting conditions have also been performed tocreate environmental conditions under (somewhat) controlled settings.
4. Conclusions
The results show that there has been much research performed on light pollution, but that thetwo disciplines ecosystems and sky brightness are at different stages of development. In
some areas, much research has been conducted. For example, quantifications of skybrightness. In other areas, however, the focus has been on specific research questions or
species, resulting in a lack of knowledge of the full width of impacts of light pollution on
ecosystems. In ecology, there has been much focus on species that are more easily studiedor handled, while many species or groups have rarely been studied at all.
Another issue is that it is important to conduct studies that can help to reduce light p ollutionby, for example, showing and presenting the results of measurements that have a local
context and can be traced back to the lighting installations. Due to a lack of establishedmethods for measuring and reporting electric light at night, it is dif ficult to establish if thereported results are generalizable, for example, whether they are relevant for practical field
conditions.

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PO63
THE EFFECT OF CHANGES IN LIGHT LEVEL ON THE NUMBERS OF CYCLISTS
1

Uttley, J.1, Fotios, S.1, Robbins, C.J.1, Moscoso, C.2, Zaikina, V.3
University of Sheffield, Sheffield, UNITED KINGDOM, 2 SINTEF Community, NORWAY,
3
University of South-Eastern Norway, NORWAY
j.uttley@sheffield.ac.uk

Abstract
1. Motivation, specific objective
In some locations cycling is considered to be a dangerous mode of transport. For example,
the 2017 British Social Attitudes Survey found that 62% of cyclists think it is too dangerous tocycle on UK roads. Cycling after dark is considered to be more dangerous than cycling in
daytime because of the apparent reduction in visibility to others
Changes in ambient light are expected to influence travel decisions because after dark thevisual system is impaired, with reductions in functions such as contrast discrimination anddepth perception and an increase in reaction time. This impairment contributes to thesignificant increase in the risk of some types of road traffic collision (RTC) in darkness
compared to daylight. It is therefore expected that, for a given time of day, there would befewer cyclists after dark than in daylight.
Road lighting is installed to reduce impairment to vision after dark. Road lighting installed tomeet the P-classes of CIE 115:2010 will have an average illuminance in the range of 2 to 15
lux, a smaller variation than the difference between daylight and dark. It would therefore beinteresting to compare the effect of changes in road lighting illuminance with changes inambient light level.
2. Methods
The effect of changes in light level on the numbers of cyclists was investig ated using datafrom automated counters in eight cities locations; Arlington, USA (33 counters), Birmingham,
UK (48), Cambridge UK (14), and 14 counters across Norway (in the cities of Bergen,
Lillestrom, Oslo, Kristiansand and Trondheim). These counters w ere all located in urban areas.
The effect of ambient light level was investigated by comparing cyclist numbers in a certain
period of the day which was daylit for one period of the year and dark for another period. Two
approaches were used. The clock-change approach compares the days just before and justafter the biannual clock change associated with daylight. The whole -year method takes
advantage of seasonal variation in daylight. This day/dark ratio for the case period iscompared with a similar ratio for control periods to establish an Odds Ratio. The control
periods are those which are permanent daylight (or permanent darkness) across the daylightand dark periods of the case period, and this account for the effects, if any, of seasonalvariations such as changes in weather and vacation periods.
The effect of changes in road lighting was established by determining odds ratios for roads ofdifferent illuminance. This was done for one city (Birmingham, UK) where estimates of roadbrightness were available from aerial photographs. Relative road brightness was estimatedusing mean pixel intensity values derived from the aerial images. Although the absolute pixel
values have no meaning, their relative magnitude in comparison to surrounding pixel values
gives an indication of relative brightness. A brightness factor was therefore calculated for 48
locations where cycle counters were present, by dividing the mean pixel value at that locationby the mean pixel value across the whole of the Birmingham district.

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3. Results
Ambient light level. An odds ratio >1.0 indicates a reduction in the numbers of cyclists after
dark compared with daylight at the same time of day. The data for these locations suggest
significant reductions of cyclists after dark:•

Arlington (clock change method): OR=1.42, 95%CI=1.41-1.44, p<0.001•

Arlington (whole year method): OR= OR=1.67, 95%CI=1.66 –1.68, p<0.001•

Birmingham (whole year method): OR=1.32, 95%CI=1.31–1.33, p<0.001.

•

Cambridge (clock change method): OR=1.57, 95%CI=1.52-1.62, p<0.001•

Norway (clock change method): OR=1.13, 95%CI=1.10-1.16, p<0.001•

Norway (whole year method): OR=1.05, 95%CI=1.03-1.06, p<0.001

The suggested odds ratio thresholds for marking small and medium effect sizes are 1.22 and1.58 respectively. For locations in the UK and the USA the odds ratios for the effect of
ambient light (1.32 to 1.67) indicate a small to medium effect, an impact which is considered
to be of practical relevance.
Road brightness. The odds ratios range from about 2.0 for a brightness factor of 1.0,
following an exponential trend and reducing to an odds ratio of about 1.0 for brightness
factors of 1.5 or more. In other words, a brightness factor of 1.5 was sufficient to offset theeffect of darkness. A BF of 1.5 is equivalent to an illuminance of approximately 9 lux, basedon the relationship between pixel values and measured illuminances calculated from the
Birmingham aerial images in previous research. A more accurate measurement of therelationship between illuminance and the effect of darkness on cycling rates is needed
however. In current work we are using photometric surveys rather than aerial photography toestimate lighting conditions at multiple cycle counter locations across six further urban areasin the UK.
4. Conclusions
These data show that changes in lighting are associated with changes in cyclist numbers.
Lighting is therefore suggested to be a suitable tool for promoting cycling, a climate -mitigating
policy for many nations. These data also contribute to guidance for wh ere and how muchlighting might be of benefit to cyclists.

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PO64
MODELLING OF VERTICAL SURFACES RADIATION IN CONNECTION WITH THE
EVALUATION OF THE OBTRUSIVE LIGHT
Novak, T.1, Becak, P.2, Valicek, P.3, Latal, J.4, Martinek, R.5
VSB-TUO Faculty of Electrical Engineering and Computer Science, Ostrava, CZECHREPUBLIC,
tomas.novak1@vsb.cz

Abstract
1. Motivation, specific objective
At present, in the context of the night outdoor space, the issue of the obtrusive light isbecoming more and more pronounced. The road lighting is the most associated with obtrusive
light, which is an integral part of the cities and villages. However, it is necessary to realizethat within the night outdoor space, other light sources (lighting systems) contribute to theradiation to the upper hemisphere, too. These sources can significantly decrease thedominance of the road lighting. It is necessary to take into account other important lightsources that radiate to the upper hemisphere for example advertisings (billboards), windows,
shop windows, cars, architectural lighting, lighting of the commercial and industrial centers,
railways, etc. From the above mentioned there are many types of light sources radiating to theupper hemisphere, most of them are dynamic and distributed within a large area not only of
the cities and villages.
The issue of the radiation to the upper hemisphere is therefore very broad and complex. The
first step to solve this problem have to be quantification of the radiation of the individual
sources and then an assessment of their contributions to the overall radiation to the upper
hemisphere.
2. Methods
The paper will deal with the modelling of the vertical surface radiations. It can besupplemented to the modelling of the radiation of standard lighting systems, such as roadlighting. What can we imagine by radiation of the vertical surfaces? These are mainly large
advertising banners on the facades of buildings, billboards and screens advertisements.
However, we shouldn´t forget the illuminated facades with "clas sic" architectural lighting, shop
windows, office buildings windows, but also the classic windows in residential buildings, whichmust also be included in the radiation to the upper hemisphere from artificial light sources not
for their high luminance or significant area, but especially for their high number.
3. Results and Conclusions
The paper will present an approach to unify the behavior of these types of light sources.
These will be understood as cosine radiators. If this cosine distribution curve is t aken into
account, then only the luminance and the light-active surface can be known to supplement the
information about the radiation of such the light source. The luminance can be obtained
relatively easily from real field measurements of the luminance a nd the radiated surface canbe subtracted from online maps. The article presents the implementation of this data into
lighting calculations and the creation of the distribution curves which are necessary for theradiation calculations of these surfaces.
The paper will also analyze the influence of the luminance and active areas on the radiatedluminous flux and assign these values to the real radiators from the smallest windows,
through billboards to large advertisements placed on the walls of high -rise buildings.

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PO65
USEFUL CONTRAST INDEX AS A METRIC FOR ROADWAY LIGHTING
1

AbouElhamd, A.R.1, Saraiji, R.2
United Arab Emirates University, Al Ain, UNITED ARAB EMIRATES, 2 Center of healthybuilding research at Ajman University, Ajman, UNITED ARAB EMIRATESAmira.ragab@uaeu.ac.ae

Abstract
1. Motivation, specific objective
Roadway lighting standards specify horizontal illuminance or luminance at the roadway
surface for various roadway categories. Although the luminance and illuminance method
incorporate some factors that affect human visibility, other important factors such as thetarget’s contrast is not considered. Roadway lighting standards should consider how thehuman visual system detects objects to improve visibility for drivers. This study proposes a
new metric that has the potential to incorporate visibility for drivers during night -time. The
metric is based on the contrast of targets and is named Useful Contrast Index (UCI).
2. Methods
The study utilized computer simulation to investigate the lighting en vironment in a two-laneroad. The road configuration includes five obstacles (targets) that are located along the lateral
direction of the road. These targets are labelled according to their lateral position as seen bya driver as follows: left (l), left-centre (lc), centre (c), right-centre (rc), and right (r). For
example, (r) is the target that is on the right side of the road as seen by the driver. Eachtarget is subdivided vertically into three sub-targets at 0.05 m, 0.5 m, and 1.0 m relative to theground. These heights were selected to represent possible obstacles in a road such as rocks,
animals, children, and adult pedestrians. This set of five targets is repeated at equal intervals
along the longitudinal direction of the road to cover the area betw een two poles. A driver ispositioned at a distance equals to the total stopping distance from each target. The luminanceof all sub-targets and their corresponding background were determined using three dimensional vector analysis. A vector starts from dr ivers’ eye and passes through a specifictarget segment to define the exact intersection point with the background. A contrast value isthen obtained for each target segment. If the contrast value of a specific sub -target is greaterthan a contrast threshold, then the contrast is classified as useful contrast. A useful contrast
is when the target contrast is greater than the positive contrast threshold or more negative
than the negative contrast threshold. If the target contrast is close to zero and less th an thepositive contrast threshold, or less negative than the negative contrast threshold, then it will
be classified as non-useful. The values of the contrast thresholds were determined following
two methods; 1) the Adrian model (Adrian, 1989), and 2) the Small Target Visibility Model(STV) (IESNA, 2014). Once the contrast values were found at each target point, a usefulcontrast index (UCI) is developed for each target height and for the whole road. We define theuseful contrast index as the percentage of targets that have contrast value greater that thecontrast threshold along the length of the road. We show how UCI changes when we change
the spacing between the poles. The analysis discussed in this paper includes three different
values for UCI; a) positive UCI which only considers the positive contrast, b) negative UCI
which only considers the negative contrast, and c) the overall (both positive and negative)
UCI. We also discuss the UCI for the three possible targets’ heights and the five lateral target
locations.
3. Results
We found that when the target height is higher, the overall UCI and the negative UCI become
smaller, whereas the positive UCI becomes larger.
The lateral position of targets also affects the total UCI, the positive UCI and the negat ive UCI.
We found that the overall UCI on the center (c) and left-center (LC) has the smallest

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percentage of targets with contrast greater than the contrast threshold. On the other hand, theright (r) position showed the highest percentage of targets that has contrast values greaterthat the contrast threshold. The total UCI became lower when the pole spacing was increased.
The reduction was more pronounced when we changed the spacing from 20 m to 30, and from50 m to 60 m. The negative UCI dropped as pole spacing was increased. Similarly, thepositive UCI for high targets at 1.0 m dropped with larger pole spacing.
4. Conclusions
We found the Useful Contrast Index to be a valuable metric for roadway lighting. the objective
is to maximize UCI for better roadway lighting. We believe that this metric gives insights on
target’s visibility and has the potential to be part of roadway lighting standards.

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PO67
LIGHT EXPOSURE OF WORKERS IN DIFFERENT OCCUPATIONS
Udovicic, L. and Varga, C.
Federal Institute for Occupational Safety and Health (BAuA), Dortmund, GERMANY
udovicic.ljiljana@baua.bund.de

Abstract
1. Motivation
Light is the most important stimulus for synchronizing endogenous circadian processes in th e
human body to the natural day-and-night rhythm. Light exposure at night (e.g. during night
shift work) as well as low daytime light levels (caused by predominantly indoor activities andtoo little time spent outdoors) can contribute to circadian desynchr onization of theseprocesses. The desynchronization, in turn, has been associated to a number of diseases suchas cardiovascular diseases, metabolic disorders, depression and even an increased cancer
risk.
As the knowledge of the actual light exposure encountered by workers is still limited, we are
evaluating in an ongoing field study the light exposure of various occupations: occupations
with employees working night shifts and being therefore exposed to light at night, those withlow light exposure during the day as well as outdoor occupations. The overall aim of the study
is to evaluate the feasibility of developing a job exposure matrix (JEM) as a tool for estimating
occupational exposures in epidemiological studies. Here, the JEM would comprise the light
exposure levels and the occupation, taking into account seasonal dependency.
The contribution will present results on light exposure of different occupations assessed in2020.
2. Methods
Participants in the field study measured personal light exposures co ntinuously over one week
in two different seasons. Light exposure data were collected during all daytime activities using
a commercial actimetry device ActTrust (Condor Instruments), attached on the outer layer ofclothing at chest height. Before the devices were used in the study, they were calibrated in
our optical laboratory. Simultaneously with the participants’ measurements, daylightirradiance was recorded using the spectroradiometer CAS 140CT (Instrument Systems).
When in bed to sleep, the participants were instructed to place the devices on the bedsidetable in order to measure bedroom light levels. Therefore, the collected data contain the 24hour light exposure from natural and artificial light sources. The interpretation of personal light
exposure data was supported by a participants’ activity diary, recording the periods of indoor(at the workplace, at home) or outdoor time (at the workplace, walking, doing sports).
Before the first data collection, the participants were informed about the goal of the study.
They provided written consent and were completely free to withdraw at any time. The data
were stored and processed anonymously. An ethics committee has given a positive vote forthe study.
3. Results
Light exposures were assessed in the winter and summer season of 2020. The number of 80
participants in January/February 2020 was reduced to 61 in May/June 2020 due to the SARS CoV-2 pandemic. Night shift working elderly care nurses and order pickers were recruited asworkers being exposed to light at night. Daytime working hotel staff, order pickers andsoftware developers represented the occupations supposed to have low daytime light levels.
Occupations mainly working outdoors were gardeners, street cleaners and waste collectors.

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In this contribution, the light exposure will be presented as illuminance values. Although
actually describing the effect of light on the visual system, higher illuminance levels usuallymean a higher circadian influence. The measured illuminance values were averaged over one
hour in order to obtain 24 values per working day. To obtain the mean hourly illuminance for a
specific occupation, all available working days for this occupation were averaged. The
average levels of illuminance show the effects of selected times of da y (morning, midday,
afternoon, night), season (winter, summer) and place of activity (indoor, outdoor). Luminous
exposures in lx∙h and exposure times above certain illuminance thresholds for mentioned
occupations will be presented.

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WORKSHOPS

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WS1
Integrative lighting applications: advances, guidelines and roadmap
Conveners: Luc Schlangen, NL & Peter Thorns, GB

Summary
The recently published e-ILV update introduces the new term integrative lighting and defines
it as lighting that integrates both visual and-non-visual effects to produce physiological andpsychological benefits upon humans.
While the more conventional visual qualities remain important, also ‘non-visual’ effects suchas those on the circadian system, sleep and alertness are important considerations in
integrative lighting designs. This makes integrative lighting a promising route for optimizing
visual perception, comfort and psychological reinforcement, while simultaneously maximizing
health and well-being of users. Integrative lighting considers what light is appropriate for aparticular time of day, context and group of users. In this workshop the recommendations of
the 2nd international workshop on circadian and neurophysiological photometry (2019) will be
discussed. These recommendations use the melanopsin-based metrology of international
standard CIE S 026:2018 to account for ipRGCs photoreception and provide some i nitial
guidance on healthy daytime, evening and night-time light exposures in day active people.
Next to this, the workshop will discuss recent insights and advances in recommendations withrespect to what illuminances and lighting designs to use for users with ages beyond 50.
Thirdly, the workshop will discuss ongoing activities to establish an authoritative set of lighting
requirements for humans in indoor workplaces that meet the needs for visual comfort andperformance of people with a normal visual capacity. The workshop closes with a forum
discussion in which all these perspectives are combined in a mind map with current steps andfuture directions for integrative lighting applications.

Workshop presenters:
 Luke Price, GB: Recommendations for healthy light exposures from the 2nd international
workshop on circadian and neurophysiological photometry
 Yukio Akashi, JP: Specific lighting guidance for people aged 50+, CIE 227:2017 Lighting
for Older People and People with Visual Impairment in Buildings
 Etsuko Mochizuki, JP / Peter Dehoff, AT: Lighting for indoor workplaces – how can we give
more guidance?

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WS2
Adaptive road lighting
Convener: Dionyz Gasparovsky, SK

Summary
Need for lighting of roads varies throughout evening and night. Depending on traffic situation,
weather conditions, climatic and seasonal changes, presence and movement of people andmany other factors, the lighting should adapt itself optimally to satisfy requirements to visualperformance, visual comfort and aesthetical presence in respect to different types of users. It
is essential for adaptive lighting to balance between actual needs of different user groups anduser patterns sharing the same outdoor space, mitigating any adverse effects of light on thesurroundings. Moreover, 'smart' lighting should be able to predict behaviour of users in realtime and react to such extraordinary and unexpected situations as traffic accidents, work onroad or criminal acts. The workshop is intended to support works in Technical Committees TC
4-62 and TC 4-51 by creating platform for presentation of the newest knowledge andgathering ideas from wider audience of participating stakeholders, experts and professionals.

Workshop presenters
 WP01: Costis Bouroussis, GR: A HOLISTIC METHOD FOR THE COMMISSIONING AND
OPTIMIZATION OF ADAPTIVE ROAD LIGHTING SYSTEMS USING LABORATORY AND
FIELD MEASUREMENTS
 WP02: Dionyz Gasparovsky, SK: ASSESSMENT OF ROAD LIGHTING PERFORMANCEFOR TRAFFIC INTENSITY AND TRAFFIC DETECTION BASED LIGHTING ADAPTATION

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WS3
Tutorial on
Enhancement of images for colour-deficient observers
Convener: Po-Chieh Hung, US

SummaryThis tutorial will provide a summary and background information to the publication CIE
240:2020 Enhancement of Images for Colour-Deficient Observers.
The tutorial will include:

cone sensitivity of CDO (including CNO, anomalous trichromat, dichromat);

optical solutions for enhancement (including optical filter ing and lighting solutions);

image processing solutions for enhancement;

overview of some evaluation methods of the enhancement techniques to be proposedin the future.

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WS4
Integrative lighting applications: advances, guidelines and roadmap
Convener: Tony Bergen, AU

Summary
The field of photometry and radiometry often involves measurements of distributions. This canbe single-dimension distributions, e.g. spectral measurements and time -resolved
measurements; two-dimension distributions, e.g. goniophotometry and field illuminancemeasurement; three-dimension distributions, e.g. goniospectroradiometry and hyperspectral
imaging; and in some cases higher dimensions.
When a distribution is measured it is normally not measured in its entirety – instead the
distribution is sampled at regular intervals. The choice of sampling interval has an impact onany evaluation of the distribution as well as any derived quantities. Furthermore, the samplinginterval needs to be considered in the determination of the uncertainties of measurement.
Taking more measurements, i.e. decreasing the sampling interval, may give a more complete
picture of the distribution being measured, but it may also come at the expense of taking moretime to acquire and of producing too much data. There is a science called sampling theory
which provides guidance for determining the optimum sampling interval so that the di stribution
is adequately described, but sampling theory is often too mathematically involved for many
people performing basic measurements.
The intention of this workshop is to provide some practical guidance on how to determine theideal sampling interval in order to optimise the trade-off between measurement accuracy andmeasurement speed. The workshop is suitable for everyone dealing with measurements in all
aspects of photometry and radiometry.

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WS5
Methods for measuring discomfort from glare
Convener: Steve Fotios, GB

Summary
As stated in CIE 243:2021 there is still no reliable model of discomfort from glare and one
reason for this is insufficient consideration of methodology: test procedures are often weak(e.g. condition orders were not counterbalanced) and range bias is rarely (if ever) considered.
That leads to noise and bias in the data and hence to disparity in models fitted to different
sets of data. This aim of this workshop is to raise awareness of these issues and to discuss
the steps that might improve future research of discomfort from glare.

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WS6
Pre‐vitamin D action spectrum: challenging CIE towards a standard
Convener: Ann Webb, GB

Summary
The CIE pre-vitamin D action spectrum was published as a TC report in 2006 (CIE 174:2006
Action spectrum for the production of previtamin D3 in human skin). CIE p ractice is to allow
such action spectra to be evaluated by the community, and then move towards a standard.
The 2006 action spectrum is widely used, which shows a level of acceptance. However, this isalso likely because none of the challengers (so-called QUT and RIVM versions) can provethat they are better (clearly more correct/produce more realistic or experimentally validated
outcomes). This does not necessarily mean the CIE version represents the truth, just a
consensus that it is better the community use a single action spectrum and this one has theweight of an international body behind it. The full TC report shows that the authors were wellaware of the limited data they had at their disposal, and the assumptions they had to make indeveloping this action spectrum. Can we now improve on this, or has it indeed stood the testof time? Given the current interest in vitamin D, now would seem a good time for CIE toconsider whether the existing CIE pre-vitamin D action spectrum is robust enough to engagea TC to move towards making it a Standard. For that to happen it needs to withstand scrutiny.
The aim of the workshop would be to consider whether the time is right for establishing astandard, with or without amendments to the current version, or whether m ore work isneeded.

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WS7
Revision of ISO/CIE 19476 and CIE S 025
Convener: Armin Sperling, DE

Summary
In 2013 CIE published CIE S 023:2013 “Characterisation of the Performance of Illuminance
Meters and Luminance Meters”. This was transferred into a dual logo standard with ISO andpublished as ISO/CIE 19476:2014 “Characterization of the Performance of Illuminance Metersand Luminance Meters”. This was identified as requiring revision in a systematic review heldin 2019. For implementation the CIE TC 2-96 was recently established in D2.
In 2015 CIE published CIE S 025:2015 “Test Method for LED Lamps, LED Luminaires and
LED Modules”. The standard has now had over five years of use and is becoming widespreadin its application. In the coming years we will have the opportunity to revise the standard to
take into account new knowledge and to address any deficiencies that may be identified withthe standard.
There is a European research project EMPIR 19NRM02 RevStdLED which is advancing
research in areas that are key to these two publication revisions. The CIE is identified as a
key stakeholder in this project, and the project work packages are directly relevant: Traceable measurements using ILMDs(related to CIE S 025)

 Spectral correlations in photometric quantities(related to CIE S 025)

 Complementing spectral mismatch index(related to ISO/CIE 19476)

 Comparison of spatial distributions(related to CIE S 025)

The intention of this workshop is to provide an introduction to the revision of these twostandards and to seek input from attendees on all aspects relating to the revision. The
workshop is suitable for everyone dealing with measurements in all aspects of photometry
and radiometry.

Workshop content:
 Short introduction to ISO/CIE 19476 and CIE S 025:


Scopes of the standards and demarcation from CIE 244

Missing items

 Workshop presentations WP03 (see below)
 Discussion on unsolved questions regarding ISO/CIE 19476:


Modified SMCF and mismatch IndexIntroduction of luminous efficiencies other than V(λ)?

Introduction of additional illuminants?

Introduction of MU evaluation regarding how to implement for calibration procedures
 how to implement for quality indices Discussion on MU in CIE S 025

Workshop presenters:
 WP03: Udo Krüger, DE: GENERAL V(λ) MISMATCH INDEX ‐ HISTORY, CURRENTSTATE, NEW IDEAS
 WP04: Ville Mantela, FI: NOVEL EVALUATION METHOD FOR GENERAL PHOTOMETERMISMATCH INDEX f1'

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WS8
Progress Report and Discussion regarding CIE TC1-98:
A Roadmap Toward Basing CIE Colorimetry on Cone Fundamentals
Convener: Lorne A. Whitehead, CA
lorne.whitehead@ubc.ca

Summary
CIE TC1-98 began work in October 2020. It will create a roadmap for the development of anew, complete, self-consistent system of CIE colorimetry measures based directly on cone
fundamentals, with explicit consideration of the impacts of variations of the cone
fundamentals due to age, field of view, and individual diversity. It will address CIE colorimetry
measures that are currently based on the XYZ colour matching functions, and will also
consider the possibility of creating new measures based on the LMS cone fundamental
functions. At present there are three working groups within TC 1 -98:
The “LMS-based CIELAB” working group is assessing the feasibility of developing a simple
LMS-based calculation similar to CIELAB but with sufficient accuracy to assess colour
appearance and colour appearance differences in many practical situations.
The “retinal diversity” working group is considering the variation of cone fundamental
functions among individuals with colour-normal vision. There are two related aspects of this
topic. First, there is a need to better characterize this variation, which could include a
recommendation for significant new international experimental efforts. Second, there is aneed to better connect between colour-matching observations and colour appearance
predictions. In particular, it is important to account for colour -contrast self-adaptation, which
to some extent reduces colour appearance differences that would otherwise be ca used byvariations of cone fundamentals.
The “extrapolation” working group is addressing a current inconsistency – the CIE now
recommends that colorimetry calculations span the wavelength range from 360nm to 830nm,
but at present the values of the cone fundamentals are not tabulated throughout that fullrange. The missing values, which are essentially negligible, are for wavelengths below 390nm
and, for the S-cone, above 615nm. This working group is developing a recommendation forfilling in those blanks.
The workshop will begin with an overview discussion and may include breakout groups to
support more detailed exchange.

Workshop presenters:Yoko Mizokami, JP: LMS CIELAB



Manuel Spitschan, GB: Retinal diversityKees Teunissen, NL: Extrapolating cone fundamentals

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