Technical Report 396

THE EFFECTS OF BANDWIDTH COI

ON IMAGE INTERPRETER PERFORMANCE

lZ". Harold Martinek

U.S. Army Research Institute

and

Alvin Zarin

U.S. Army Electronic Research and

Development Command

HUMAN FACTORS TECHNICAL AREA

DTIC

SELECTE MAR 1 3 1980

U. S. Army

C C;-L, Research Institute for the Behavioral and Social Sciences

August 1979

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FOR THE BEHAVIORAL AND SOCIAL SCIENCES

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Image interpretation Contrast

I MINT Sun angle

Digital imagery Resolution

Bandwidth compression

2(X ABsTRACT (Contfnu@ am Pavers* ie It~ if cs.Ary and Identify by block number)

1

Conventionial imagery differing in rosolution CS-inch ground resolved distance

[(;RD], 16-inch GRD, and 24-inch GRD), digitized and treated to represent four

1c'vols of bandwidth compressiodn (l:l=no compression, 4:1, 8:1, and 10:1) was

iruorerreLeci by' 12 experienced image Lnterpretcrs. A Greco-Latin square design

Wit.ý 0';'-d Lo) c-ort~rol foi, di~ffo2renccs betwoeen inLerpreters, imagery su~bsets, a [c~ Ieixi L; aL ( ri :r GD ad L Lo t.thuof[cc L., of b, ndwidthi compresor.. [1I(diuli trni.~'udi rwir~e vari-a1 b ! of ,;un a ngle, imaqo! contrast, and ----- p

DD AN1 1473 rofJrioN or I NOVs 0,S IS 09SOLETE U I Iu]. asoi f i.r.!d
"Unclassified SECURITY CLASSIFICATION OF THIS PAG(fhmen Date Itered)

2-0.

target obscurity were distributed equally across ai IuL conditions, could be

analyzed only for the 24-inch GRD imagery. Significant decreases were found in

the number of correct identifications due to bandwidth compression; the largest

decrease occurred between 4:1 and 8:1 bandwidth compression ratios. System

developers should make careful trade-off evaluations in using bandwidth compression. More research in this area is required on the search function of

interpretation and interactions of image variables. NU

I-

° "I:

Unclassified

SECURITY CLASSIFICATION OF TNIS PAGE(W7,In Dalt EnfIred)

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Technical Report 396

THE EFFECTS OF BANDWIDTH COMPRESSION

ON IMAGE INTERPRETER PERFORMANCE

Harold Martinek

U.S. Army Research Institute

and

"S r Alvin Zarin .,

U.S. Army Electronic Research and .,

Development Command

I t

Submitted by: I

Edgar M. Johnson, Chief HUMAN FACTORS TECHNICAL AREA

Approved by:

Frank J. Harris, Acting Director

ORGANIZATIONS AND SYSTEMS

RESEARCH LABORATORY

U.S. ARMY RESEARCH INSTi rui-_ FOR THE BEHAVIORAL AND SOCIAL SCIENCES

5001 Eisenhower Avenue, Alexandria, Virginia 22333

Office, Deputy Chief of Staff for Personnel

Department of the Army

August 1979

Army Project Number Sensor Syptems

20163743A774 integration and Utilization

Approved for public release, distribution unlimited.

ift
IA

ARI Research Reports and Technical Reports are intended for sponsors of

R&D tasks and for other research and military agencies. Any findings ready

for implementation at the time of publication are presented in the !ast part

of the Brief. Upon completion of a major phase of the task, formal recommendations for official action normally are conveyed to appropriate military

agencies by briefing or Disposition Form.

iv

-4-____________
FOREWORD

The Human Factors Technical Area uf the Army Research Institute for

the Behavioral and Social Sciences (ARI) is concerned with the human resource demands of increasingly complex battlefield systems for acquiring,

transmitting, processing, and disseminating information. This increased

complexity places greater demands on the operator using the machine system. Research in this area focuses on human performance problems related

to interactions within command and control centers, as well as issues of

system development. The research is concerned with such areas as software development, topographic products and procedures, tactical synmbology,

user-oriented systems, information management, staff operations and procedures, decision support, and sensor-system integration and use.

An area of special concern is the transmission of continuous-tone

imagery in digital form to ground terminals in near-real-time. This is

a prime requirement of intelligence and command-and--ZOntrol systems,

since much of the information contained in such imagery is extremely

perishablt-. A key problem of such systems is the bandwidth requirement,

for which one possible solution is he use uf baindwidth cornrcýssio techniques. This report describes resear-1 .hat partially determines the information lops in the interpretation of the imagery associated with degrees of bandwidth compression in image transmission. This rescarcih was

a cooperative project among a number of agencies including ART, the U.S.

Army Space Projects Office, RCA, Inc., of Camden, N.J., and the U.S.

Army Electronics R&D Command.

Research on sensor systems integration and utilization is conducted

as an in-house effort augmented through contracts with organizations

selected for their unique capabilities and facilities for researcn on on

sensor systems. The present in-house research was conducted in response

to general requirements of Army Project 2Q763743A774 and to special. requirements of the U.S. Army Space Projects Office, Washington, D.C.

Special requirements are contained in Human Resources Need 77-271 (Human

Factors Research and Evaluation of Advanced imaging Systems).

J EPH kJNRE 

hrnical Director

vI
THE EFFECTS OF BANDWIDTH COMPRESSION ON IMAGE

INTERPRETER PERFORMANCE

BRIEF

Requirement:

To determine the effect of bandwidth compression on the interpretability of digitized imagery.

Procedure:

Twelve experienced image interpreters were given about 3 hours of

practice/training on digitized imagery containing all the different con- ditions in the experiment. Each participant then interpreted all the

imagery in each of three "resolution sets"; first, 8-inch ground-resolved distance (GRD), vertical imagery; second, 16-inch GRD, vertical imagery; and third, 24-inch GRD, oblique imagery. Each set was divided into four

subsets of images, each of which could be viewed at one of the four levels

of bandwidth compression--l:l (no compression), 4:1; 8:1; and 10:1.

To test the effects of bandwidth compression, a Greco-Latin square design was used to control for differences between interpreters, imagery subsets, and periods at each GRD. In the 24-inch GRD (oblique imagery) target difficulty was controlled to allow testing the effects of sun

angle, image contrast, target obscurity, bandwidth compression, and their

interactions on interpreter performance. At the other two GRDs, the first

three variables were distributed equally across bandwidth compression, but could not be analyzed because of confounding with target differences in

the imagery. The number of correct identifications and number of misidentifications were analyzed for each of five reporting levels of increasing detail of target identification--from simple detection (i.e., was a target present?) to the model number of target (e.g., self-propelled gun,

M107).

Findings:

In general, the number of right responses decreased significantly

as bandwidth compression increased ?or each resolution set (8-inch, 16-

inch, and 24-inch GRD), but not for each level of detail of target iden- tification. The largest decrease in right responses was from the second

compression level (4:1) to the third compression level (8:1). Wrong identifications also tended to decrease as bandwidth compression

increased.

vii
Significant differences were found for target obscurity (only a few I hidden targets were found) and for sun angle (high sun angle was better).

Some interactions were found between bandwidth compression and sun angle and target obscurity. For example, under the low-sun-angle conditLun, A

the largest decrease in the number of right identifications due to band- A

width compression occurred at 4:1 compression level, whereas in the highsun-angle condition, the largest decrease occurred between 4:1 and 8:1

compression levels.

"Utilization of Findings:

Bandwidth compression of digitized imagery degrades interpreter performance, Users should carefully consider the trade-offs between different amounts uf bandwidth compression and the degradation of interpreter

performance. Developers of systems using bandwidth compression should

collect more data concerning its effect on search performance of trained

interpreters using large format imagery if more exact trade-off analyses

are required.

Users and developers of such systems also should collect more data

[. on the impact of the operational conditions (such as sun angle) to determine when bandwidth compression will be itu.L effective and when it should

not be used.

viii
THE EFFECTS OF BANDWIDTH COMPRESSION ON IMAGE INTERPRETER PERFORMANCE

CONTENTS

Page

INTRODUCTION .................... ..... ........................... 1

OBJECTIVE ..................... ..... ............................ 1

METHOD....................................... ME HO . . . . . . . . . . . . . . . . . . . . . . . . . . . . .•

Sample ........................... ............................ 1

Procedure .......................... ........................... 2

Variables .......................... ........................... 2

Design ........................... ............................ 3

Stimulus Materials ..................... ...................... 6

RESULTS ............................ ............................. 7

Eight-Inch Ground Resolution ............. ... ................. 7

Sixt(.en-inch Ground Resolution ............... ................ 10

Twenty-Four-Inch Ground Resolution ....... .............. 14

Summary Across Reporting Levels .......... ................ 23 -1

Summary Across GRD Levels . ................ .... 4

CONCLUSIONS .......................... ........................... 28

APPENDIX A. INTRODUCTION ............... .................... 33

B. TRAININC INSTRUCTIONS ................ ................ 35

C. TEST PROCEDURES AND I-GERY DESCRIDTION ........... 4.

SD. IMAGE %IATRICES AND TARGET LISTS .... ........... .. 45

E. CONTROL VARIABLE RESULTS .............. 59

F. SIGNIFICANCE TESTS USING THE NEWM'AN-KEULS METHOD 6/

DISTRIBUTION .......................... ........................... 69

LIST OF TABLES

Table 1. Greco-Latin square design .............. ............... 4

2. Variables within each scenario .......... ............. 5

3. Distribution of targets, 24-inch GRD, target size

vCrsus 5U!ý angle x contrast x Larget obscurity ....... .

ix
LIST OF TABLES (continued)

Table 4. Analysis of variance summary for right identifications,

independent variables versus reporting level

(8-inch GRD) .............. ......................... 7

5. Number of right identifications, bandwidth

compression level versus reporting level

(8-inch GRD) .............. ......................... 8

6. Analysis of variance summary for wrong

identifications, independent variables

versus reporting level (8-inch GRD) ..... ............ 9

7. Number of wrong identifications, bandwidth

compression level versus reporting level

(8-inch GRD) .................... ...................... 10

8. Analysis of variance summary for right

identifications, independent variables

versus reporting level (16-inch GRD) .... .......... . 11

9. Number of right identifications, bandwidth

compression level versus reporting level

(16-inch GRD) ............... ..................... . 11

10. Analysis of variance summary for wrong

identifications, independent variables

versus reporting level (16-inch GRD) .... .......... .. 12

11. Number of wrong identifications, bandwidth

compression level versus reporting level

(16-inch GRD) ............... ..................... .. 13

12. Analysis of variance summary for right

identifications, independent variables

versus reporting level (24-inch GRD) .... .......... .. 13

13. Number of right identifications, bandwidth

compression level versus reporting level

(24-inch GRD) ............... ..................... .. 14

14. Number of wrong identifications, bandwidth

compression level versus reporting level

(21-inch GRD) ..................... ..................... 15

15. Analysis of variance summary for right

identifications, bandwidth compression

level and image variables versus reporting

level (24-inch GRD) ............. .... .................. 16

x
LIST OF TABLES (continued)

Table 16. Reporting Level I: Number of correct detectionsbandwidth compression level versus sun angle x

contrast x target obscurity (24-inch GRD) ......... ... 17

17. Reporting Level I: Number of correct detections,

target obscurity versus sun angle x contrast

(24-inch GRD) .............. ..................... ... 17

18. Reporting Level II, number of correct identifications, bandwidth comprce-sion level versus sun

angle x target obscurity (24-inch GRD) ... ........ .. 18

19. Reporting Level II: Number of correct identifications, target obscurity versus bandwidth

compression level (24-inch GRD) ...... ............ .. 19

20. Reporting Level III: Number of correct identifications, bandwidth compression level versus sun

angle x contrast x target obscurity (24-inch GRD) 21

21. Reporting Level III: Number of correct identifications, bandwidth compression level versus sun

angle x target obscurity (24-inch GRD) ... ........ .. 22

22. Number of right identifications, bandwidth

compression level versus ground resolution

x reporting level ........... ................... ... 24

23. Number of wrong identifications, bandwidth

compression level versus ground resolution x

reporting level ............. .................... .. 28

LIST OF FIGURES

Figure 1. Effect of bandwidth reduction/resolution factor

on number of correct identifications for Reporting

Levels I, II, III, ana IV ............. .............. 25

2. Effect of bandwidth reduction/resolution factor

on number of wrong identifications for Reporting

Levels II and IV . . . . . .............. 29

3. Effect of bandwidth reduction/resolution factor

on number of wrong identifications for Reporting

Levels III and V ............ ................... .. 30

x i.
THE EFFECTS OF BANDWIDTH COMPRESSION ON IMAGE

INTERPRETER PERFORMANCE

INTRODUCTION

The transmission of continuous-tone imagery in digital form is of

great interest to the Department of Defense for several specific applications. One such application is the near-real-time transmission of surveillance imagery to ground terminals. This is a prime requirement of

intelligence and command-and-control systems, since much of the military

information contained in such imagery is extremely perishable. One difficulty associated with the real-time transmission of imagery is the

direct relation between image res9lution and the bandwidth used for transmission. However, large bandwidth requirements are a serious problem for

many reasons--for example, the bandwidth requirements of other systems,

antenna size, interference with other systems, time for transmission, and

jamming considerations. Unfortunately, reduced bandwidth and image degradation (and other problems) are inseparably linked in the real-time transmission of imagery.

A possible solution to this problem is the use of bandwidth compression. In this method, the digitized image is transformed to the frequency

domain where many oL the higher frequencies--possessing little image energy--are discarded. Theoretically, a minimum amount of image information

is lost, and bandwidth requirements are reduced.

OBJECTIVE

The research objective was to determine the information loss associated with different degrees of bandwidth compression in image transmission. More specifically, this research investigated the effect of levels

of bandwidth compression of digitized imagery on the number of right and

wrong target identifications made by image interpreters for variations in

operational conditions such as vertical and oblique imagery, image resolution, sun angle, image contrast, and target obscurity.

METHOD

Sample

Twelve experienced image interpreters of the U.S. Army image interpretation Center, Washington, D.C., participated in the experiment. The

interpreters varied widely in age, experience, and rank, but the sample

distribution could not be controlled to represent a particular population

of image interpreters.

L
LI

Procedure

The 12 image interpreters were first given an introduction describing the background of the experiment (Appendix A) and instructions on use

of the Vehicle Target List, U.S. Equipment Mini-key, and the Report Form

(Appendix B). To insure that the interpreters understood the instructions

and to provide practice in interpreting digital imagery of scenes portraying American equipment processed with bandwidth compression, they next

interpreted 10 vertical images containing two to three targets per image.

This first set represented imagery with a ground-resolved distance (GRD)

of 8 inches prior to compression and processing. After interpreting 6 to

10 targets at one compression level, they scored themselves, checked their

interpretations, and proceeded to a different compression level until they

completed practice at all four compression levels and on taigets fr m all

four major target categories. This procedure was repeated with 10 more

vertical images with a 16-inch GRD before compression and processing. Interpreters then received 10 oblique images (optical axis 60 degrees from

the horizontal) with a 24-inch GRD before compression and processing, and

the same procedure was repeated. In this manner, the interpreters received practice on all procedures necessary for data-collection, on the

use of the mini-key, on all target types employed, on all ground resolutions, and on all levels of bandwidth compression.

On the second day the interpreters received a short description of

test procedures and imagery (Appendix C) and began interpreting the imagery. They worked for about 50 minutes on each set of imagery (8-inch,

16-inch, and 24-inch GRD), with a 10-minute break between sets.

Variables

Dependent Variables. Two primary dependent variables were used-- >

number of right identifications and number of wrong identifications. The

wrong score was composed mainly of misidentifications (i.e., giving the

wrong name to a vehicle), but included some inventive errors (i.e., identifying a nonmilitary object as a military vehicle). Both scores were

derived at five levels of reporting detail ranging from detection (Level I:

military object versus nonmilitary object) to detailed interpretation

(Level V: model number of object). Appendix B provides a detailed deL scription of the five levels.

The image interpreters reported targets at the most detailed level

Z. ithey thought appropriate and were scored not only for this reporting

Slevel, but for all less-detailed reporting levels. Thus, an interpreter

could report an object at Reportino Level V and be scored wronq at. this

level, also be scored wrong at Level IV, but be scored right at levels

111, I1, and I.

2
Independent Variables. Seven independent variables were employed:

1. Bandwidth compression level. Four level, of compression were used: 8+ bits/pel (pel = picture element)--th4.q level had zero bandwidth

compression; 2 bits/pel--4:l bandwidth compression; 1 bit/pel--8:l bandwidth compression; and .8 bit/pel--10:l bandwidth compression.

2. Groups of interpreters. Four groups of tiree interpreter• each in.

were established. Groups were matched subjectively for abil• ty by their

supervisors.

3. Periods. Four work periods (first, seconu, third, and fourth) A

were used to control for time-related effects such as practice and

fatigue.

4. Scenario. Four scenarios were used; each scenario consisted of

an image matrix of 10 image chips (8 chips scorable).

5. Target obscurity. In the third experiment, ) ith 24-inch GRD im- I

agery, half the targets imaged were in the open and the other half were

visible but embedded in vegetation.1

6. Sun angle. In the third experiment, half the imagery was taken

with a sun angle of 62 degrees from the horizontal, and the other half of

the imagery was taken with a sun angle of 18 degrees from the horizontal.

7. Contrast. In the third experiment, half the imagery was processed

to produce a high-contrast image (i.e., with dense blark shadow), and the

other half was processed to produce low-contrast images (i.e., with light

but visible shadows). No physical measurements of the resulting contrast

levels were made. 1

Design

To simplify the research design, each of the three ground resolutions was considered as separate experiment: I, 8-inch GRD; II, 16-inch GRD;

and III, 24-inch GRD. An identical Greco-Latin square was used in each

cxperiment to counterbalance the independent variables--groups, scenarios,

periods, and bandwidth compression levels (Table 1). A 2 x 2 x 2 arranaement of the image variables--sun angle, contrast, and target obscurity--

was present in each scenario, as shown in Table 2. Since each image contained different targets, image variables became confounded with target

1

In experimer' 3, the imagery was obtained in the laboratory using models

wherein targeL difficulty and image variables could be controlled. In

experiments 1 and 2, the imagery was selected from a library of U.8. Army

maneuver photography; the judgment of iinLerpreters and "take" conditions

were used to define the target difficulty and image variables. j

3! i - r -_.
--type and were not analyzed for the 8-inch and 16-inch imagery. However,

for the 24-inch ground resolution imagery, sufficient control of target

type was possible to roughly equalize estimated target difficulty across

these variables; hence, an analysis could be performed for 24-inch GRD

imagery without serious confounding (see Table 3). A 2 x 2 x 2 x 4 factorial analysis of variance design was used to investigate the variables--

sun angle, contrast, target obscurity, bandwidth compression level--and

their interactions.

Table 1

Greco-Latin Square Design

Period

Group 1 2 3 4

G 1 T 4/S 1 T 1/S 4 T 3/S 3 T 2 /S 2

G T1/S T4/S T2/S T3/S

S3T /S T3/S1 TI/S2 T1/S2T 4/

G4 T3/S2 T2/S3 T4/S4 TI/S1

Note: T bandwidth compression level; S = scenario. I

Theoretically, each of the above analyses could have been carried

out for each of the five reporting levels and for each of the dependent

variables (right identification and wrong identifications). In some cases,

however, insufficient data were availab'.e for analysis, e.g., right identifications at the level of greatest target detail (Reporting Level V). -

A

Stimulus Materials

Four sets of scenarios for each experiment were constructed to meet

experimental design considerations while simulating operational conditions. Each scenario consisted of an image mosaic of 10 image chips

(positive transparencies). Eight of these image chips contained from

one to six targets and were used to obtain the experimental data. The

other two chips contained no targets and were included to reduce the

attractiveness of guessing; any reports made for these chips were not

used in the analyses.

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The chips were arranged in the image mosaic as shown in Appendix D

(Figure D-l). The lower position of the mosaic contained a rectangular

array of numbers. The numbers in the top row were mosaic identification

numbers, and the numbers in the lower four rows were the image identification numbers corresponding to the 10 image chips.

Each of the eight chips containing targets represented one combination of the bilevel independent variables--sun angle, contrast, and target obscurity. An attempt was made to insure that at least two chips

contained one target each from the four major target categories (tracked

vehicles--armor, wheeled vehicles, engineer equipment; and miscellaneous--

trailers, towed artillery, or aircraft). Thus, each scenario represented

a wide variety of operational conditions.

Actually, only the 24-inch resolution scenarios (Table 3) met these

specifications sufficiently for analysis purposes. These scenarios were

photographed using detailed tar4et models displayed on a realistic terrain board of 1:80 scale, to obtain the desired distribution of conditions.

The 8-inch and 16-inch GRD scenarios (vertical photography) used imagery

photographed over the Camp Drum Military Reservation in upper New York

State. This imagery contained few target objects of engineer equipment

or of the miscellaneous category, but it did satisfy most of the other

design requirements.

A few gaps in the desired design of scenarios occurred because of

the lack of suitable imagery or because of problems concerning image

digitization. Appendix D gives the image matrix and tragets contained

in each image. A complete discussion of the details of the digitization

and bandwidth compression (two-dimensional cosine transform) of the

is given in Butler, et al., 1975.2

RESULTS

The Greco-Latin square design controlled for differences among interpreters, scenarios, and periods in testing the effects of bandwidth compression on interpreter performance. Data are presented in this section

only for the bandwidth compression variable. The data and results for

each experiment for the control variables--groups, scenarios, and periods--

appear in Appendix E.

For each situation where the bandwidth compression variable produced

a siqnificant change in interpreter performance, the differences in mean

[)orformanco between the four levels were testLed usinq the Newman-Keuls

Tc t. (Sue Appendix F for detailed results.)

HniL I'r, J., Di li.-sso, E., Martil:.i on, I,., lNillid juk, J., and Wild,

(U) Diqin.La Data Transmission System Study (PSECET). RCA Government

Crmmruiij.catJotis Sys tcms Divm.ision, Contract DACA 76-75-C-0003, For U.S.

'xrm'/ 1nI ricer 'Tor)nrapJhic Thiboro torJes , 17 December 1975.
The results of the analyses of variance for the three parallel experiments (8-inch GRD, 16-inch GRD, and 24-inch GRD) are reported separately--first for the right identifications for each reporting level and

then for the wrong identifications for each reporting level. Next, additional analyses concerning the image variables and bandwidth compression

are given for the 24-inch GRD imagery. Finally, the results are summarized across the three experiments.

Eight-Inch Ground Resolution

Right Identification Scores. Table 4 shows the results of the analyses of variance for the number of right identifications for the indepen- dent variables versus four reporting levels. (Reporting Level V was

omitted because of insufficient data.) Bandwidth compression level and

scenario (discussed in Appendix E) were associated with significant differences at one or more reporting levels.

At Reporting Level I, there was no significant deterioration in

performance. At this level, the interpreter is making a target/nontarget

judgment for each spot on the image that attracts his attention. This

decision appears to be made with about the samne level of proficiency at

all bandwidth levels.

Table 4

Analysis of Variance Summary for Right

Identifications, Independent Variables

Versus Reporting Level (8-inch GRD)

Reporting level

Independent variable I II III IV Va

Groups

Periods

Bandwidth compression

level **

Scenario ** •   ** 

Residual

"**Siqnificarit at the .01 level.

[ r,:;]I tF ic en L la La.
At Reporting Level II, compression produced a significant effect.

At this level, the number of right identifications is higher for the 8+

bits/pel level than for the other three bandwidth levels (see Table 5).

At Reporting Level II, the interpreter must identify the class of vehicle--

tracked, wheeled, trailer-artillery-aircraft, or engineer equipment. The

task of identifying the cues and signatures necessary for successfully

distinguishing among the four target categories was significantly affected

by bandwidth compression.

The data on Reporting Levels III, IV, and V indicated that these

more detailed interpretations were very difficult to make at any level

of bandwidth compression. There was a 50% reduction in the number of

right identifications for each reporting level. However, there were no

significant differences in performance due to bandwidth compression.

Table 5

Number of Right Identifications,

Bandwidth Compression Level Versus Reporting

Level (8-inch GRD)

Bandwidth compression Reporting level

level I II III IV Va

8+ bits/pel 108 96 48 22 6

2 bits/pel 100 74 37 16 8

1 bit/pel 86 60 39 20 9

0.8 bit/pel 93 78 37 20 7

ainsufficient data--not analyzed.

For the relatively simple task of detection (Reporting Level I) with

the best quality imagery (8+ bits/pel), the interpreters made 108 correct

detections out of the 165 possible; that is, they detected about 63% of

the available targets. This very low performance resulted from the conditions of the experiment--not the quality of the interpreters. Interpreters typically are not trained or experienced in the recognition factors of American equipment portrayed in the images, nor on digitized

imagery of any kind. Additionally, the experimental procedurce, •piipmeilL,

and unusual conditions also could have reduced the level of performance.

Since the uxperimental imagery did not include continuous-tone imagery as

a control, the effect of' digitizing alcng could not be aseb.d. Thus,

although the relative effects of bandwidth compression and other factors

can be determined, the operational level of performance anticipated cannot be assessod.
In summary, bandwidth compression apparently did not affect detection but did affect the first level of identification. Other levels of

identifications apparently were not significantly affected.

Wrong Identi~iiation Scores. Table 6 gives the result of the analyses of variance for independent variables versus the five reporting levels.

The three significant variables are groups, bandwidth compression, and

scenarios. Group and scenario effects are given in Appendix E.

S'i Table G

$Aralysis of Variance Summary for Wrong S• identifications, Independent Variables Versus

S,•Reporting Level (8-inch GR!D)..... ----

S~Reporting level

Independent variables Ta II TII IV V

Groups

Periods

Compression

levels - *

Scenarios - ** ** * **

Residual

*Sigpniýicant at the .05 level.

**Signiricant at the .01 aevel.

a Isfficen data.

Bandwidth compression levels differed significantly for Reporting

Level III f,,: the number of wrorng identificatic 3 made. Table 7 presents

the number -f wrong identifications by bandwidth compression leve.l and.

reporting level. At a compression ratio of 8:1 (1 hit/pel), the number

of wrong identifications is much lower than for any of the other three

compression level;. The reasorn for this is not known. Compounding the

confusion, !,erforirance is poorest at both 8 bits/pel and .8 bit/pel.

9_
Table 7

Number of Wrong Identifications, Bandwidth

Compression Level Versus Reporting Level (8-inch GRD)

Bandwidth compression Reporting level

level Ia II III IV V

8+ bits/pel - 10 34 38 40

2 bits/pel - 15 23 32 31

1 bit/pel - 16 14 22 25

.8 bit/pel - 11 31 31 31

aInsufficient data.

Sixteen-Inch Ground Resolution

Right Identification Scores. Table 8 gives the analysis of variance

summary for the right identifications by independent variables versus reporting level. All the independent variables were associated with signif- icant differences at one or more of the reporting levels. In addition, a

significant residual was found for Reporting Level I, indicating that the

assumption of no interactions among the independent variables is not verified. Thus, it is possible that two or more variables could have interacted to produce a significant effect in another one. Only the compression variable is discussed in this section; the other variables are

described in Appendix E.

Significant differences (Table 8) in performance due to bandwidth

compression were found at each reporting level. Table 9 gives the number

of right identifications for bandwidth compression level versus reporting

level. The greater the bandwidth compression, the poorer the performance,

with but one (minor) inversion.

As with the 8-inch GRD results, there was a sharp drop in performance after Reporting Level II--even to the extent of precluding analysis

at Reporting Level V. However, significant differences were found for the

four compression levels tested, clea5ly indicating the detrimental effect

of bandwidth compression on performance. The largest effect occurred at

the 1 bit/pel compreFsibv level for Reporting Levels I, II, and III, and

at the 2 bits/pel For c eporting Level TV.

10
1 -- .. .

Table 6

Analysis of Variance Summary for Right

Identifications, Independent Variables Versus

Reporting Level (16-inch GRD)

Independent Reporting level

variables I II III IV Va

Groups ** -

Periods * -

Bandwidth compression

level **   -

Scenario **  ** -

Residual.*

*Significant at the .05 level.I

**Significant at the .01 level. i

a Insufficient data.

Table 9

Number of Right Identifications, Bandwidth

Compression Level Versus Reporting Level (16-inch GRD)

Bandwidth compression Reporting level

level I III IV Va

8+ bits/pel 93 67 31 17 -

2 bits/pel 89 61 20 7 -

1 bit/pel 66 37 7 3 -

.8 bit/pel 59 31 6 5 -

a

Insufficient data.

Wrong Idcntification Scores. Table 10 presents the analysis of

variance summary for independent variables versus reporting level. The

only independent variable on which 1,orformainie differcd ;icnif iantIv

li
was bandwidth compression. Reporting Level V had a significant residual,

indicating that there may have been interactions among the independent

variables.

Table 10

Analysis of Variance Summary for Wrong

Identifications, Independent Variables Versus

Reporting Level (16-inch GRD)

Independent Reporting level

variable a I III IV V

Groups S* 

Periods

b- Bandwidth compression

level

2 "Scenario

Residual -

*Significant at the .05 level.

a Insufficient data.

Table 11 shows the number of wrong identifications for bandwidth

compression level by reporting level. The number of wrong identifications differed significantly among bandwidth compression levels for Reporting Levels IV dand V. The number of wrong responses decreased with

an increase in bandwidth compression level for these rerorting levels.

in both experiments, there was a decrease in right identifications

associated with bandwidth compression and also a decrease in wrong identifications. Bandwidth compression acted to decrease the overall output

of interpreters (total number of identificatlo".s attempted) . As the

image became more degraded, the interpreter was less able to make the

more precise identifications and did not attempt to do so.

Twenty-Four-lnch _'round Nsolution

Right Identification Scores. Table 12 r r~r'c tho an 1yCiscf varlance summary for independent variablc3 versus reportinq level for the

number of right identifications. Bandwidtii coinnres.ion level is the onl:

12
variable for which significant differences were obtained. Table 13 gives

the number of correct identifications for bandwidth compression level by

reporting level.

Table 11

Number of Wrong Identifications, Bandwidth

Compression Level Versus Reporting Level (16-inch GRD)

Bandwidth compression Reporting level

level Ia II III IV V

6 8+ bits/pel - 21 26 22 22

2 bits/pal - 18 21 11 8

1I bit/pel - 13 10 4 2

.8 bit/pel - i8 16 7 6

a Insufficient data.

Table 12

Analysis of Variance Summary for Right

Identifications, Independent Variables Versus

Reporting Level (24-inch GRD)

Independent Reporting level

variables II III IV Va

Groups

Periods

Bandwidth compression

level **  

Scenario

Re.sidual

"** gignificant at the .01 level.

aInsufficient data.

13 . . . . .. . -- = • < i l
I

Table 13

Number of Right Identifications, Bandwidth

Compression Level Versus Reporting Level (24-inch GRD)

Bandwidth compression Reporting level

level I II i11 IV Va

8+ bits/pel 72 48 18 9 -

2 bits/pel 67 41 16 6 -

1 bit/pel 54 17 3 1 -

.8 bit/pel 55 21 2 0 -

aInsufficient data.

At Reporting Level 1, detection, the imbei. of right identifications

declined with increasing bandwidth compression, although no statistically

significant differences were found. For Reporting Levels I1, III, and IV,

there was a statistically significant decrease in correct identifications

as bandwidth compression level increased. As in the previous experiments,

the largest decrease occurred between compression levels 4:1 and 8:1.

Wrong Identification Scores. None of the independent variables was

associated with a significant outcome at any reporting level; therefore,

no analysis of variance summary is given.

For comparison with other results, Table 14 presents the number of

wrong identifications for bandwidth compression level versus reporting

level. These data will be used in a subsequent discussion and are reported here simply for convenience.

Effect of Image Variables on Interpreter Performances. As described

earlier, the 24-inch ground resolution experiment provided sufficient control of target type and size to permit a rough equalization of target

difficulty across bandwidth compression level, sun angle, contrast, and

target obscurity, making possible a 2 x 2 x 2 x 4 analysis of variance

design. The low number of wrong responses precluded their analysis. The

number of right identifications were analzed at Reporting Levels I, II,

and III only. The number of responses for tho other two levels were

insufficient to justify a breakout for the 2 x 2 x 2 x 4 analysis. The

reSultS Uf thi audlySis OL• dls •=paaLt~ly ýd by reporting level and

then combined. Since the 24-inch grourd resclution imagery was oblique

photography, generalization of results to vertical imagery should be done

with caution.

14
-- 2 Yj _ _ _ __ _ _ __ _ _ _

Table 14

Number of Wrong Identifications, Bandwidth

. Compression Level Versus Reporting Level (24-inch GRD)

.--Bandwidth compression Reporting level

level Ia II III IV Va

8--+ bits/pel - 17 18 9 -

2 bits/pel - 23 15 6 -

1 bit/pell - 22 17 5 -

.8 bit/pel - 20 11 4 -

alnsuffici,.nt data.

Reporting Level I. Table 1 shows that target obscurity, sun angle,

and the three-way interaction among target obscurity-contrast-sun angle

* .significantly affected interpreter performance. Table 16 shows -he frequency of correct responses presented by bandwidth compression levt' versus target obscurity-contrast-sun angle. This table details the two main

effects and one triple interaction that were statistically significant.

For example, the number of obscured targets detected can be determined

by adding the four left-hand column totals to give the sum of 45 correct

detections for obscured targets. The total of unobscured targets detected

is the sum of the four right-hand column totals, or 205 target detections.

Subjects detected more t-an 4.5 times as many unobscured taroets as targets obscured by vegetation. clearly, a blob in the open was much easier

to recognize as a target than the same blob surrounded by similar blobs

of vegetation.

Sun angle significantly affected interpreter performance. The sum totals of all columns Labeled high sun angle in Table 23 yield 141 targets detected. Similarly, summing the totals of those columns labeled

low sun angle gives a total of 109 targets. When the length of shadow was short, as in the case of the high sun angle, the number of coriect

detections increased.

The triple interaction among target obscurity-contrast-sun angle

signifiairtly influenced interpreter performance. Table 17 shows the

frequencies of correct responses when target obscurity is tabulated

against .uuiLrast and sun angle. These data show that, for high-contrast

imagery, the number of correct detections for high sun angle was greater

than for low s-n angle for both the obscured and unobscured targets. For

the low-contrast imagery, the high sun angle resulted in the detection of

more obscured tarjets thori the low son annIe, but hod little or no effect
-H

on the detection of unobscured targets. This fact should be of use to

mission planners in deciding when to fly surveillance missions. Trans-

.. = lated into operational terms: if the day is bright and shadows are

sharp and distinct, a mission should be flown when the sun is high; however, if a mission is required when the day is overcast and shadows are weak or ..onexistent, the mission can be flown at any time of day (given

I j•sufficient light), although a few obscured targets may be missed.

LA Table 15

Analysis of Variance Summary for Right Identifications,

Bandwidth Compression Level and Image Variables Versus

Reporting Level (24-inch GRD)

Reporting level

Variables I II III Remarks

A Bandwidth compression

level * ** Similar to previous results.

B Obscured/unobscured ** ** * Few responses for obscured

targets.

C High/low contrast

ID High/low sun angle **   High sun -,,le better.

AB **  ** See I -1've.

AC

AD * Low sun angle--gradual decrease due to bandwidth

compression. High sun

angle--abrupt change. S • BC

BD ** ** Few responses for obscured

I; targets. i CD

m ABC

ABD * See AD and B.

ACD

BCD See B above. High contrast

shows drop in low sun angle; low contrast shows

no difference.

ABCD

*Significant at the .05 level.

"S*Significant at the .01 level.

16
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Reporting Level II. Table 15 shows three significant main effects

-for Reporting Level II--compression level, target obscurity, and sun --

angle--and two significl.nt two-way interactions--one between bandwidth

compression level and target obscurity and another between target obscurity and sun angle. Table 18 shows the number of correct identifica-

-tions by bandwidth compression level versus target obscurity and sun

angle.

Table 18

Reporting Level II, Number of Correct Identifications,

Bandwidth Compression Level Versus Sun Angle x

4i Target Obscurity (24-inch GRD)

Obscured Unobscured

Bandwidth

compression High sun Low sun High sun Low sun

level angle angle angle angle Total

8+ bits/pel 4 C, 28 16 48

7 I2 bits/'pel 3 3 25 10 41

1 bit/pel 0 0 11 6 17

.8 bit/pel 1 0 13 7 21

Total 8 3 77 39 127

Bandwidth compression level produced a significant effect on interpreter performance. For the no-compression condition (8+ bits/pel) and

for the 4:1 compression condition, the number of correct responses was

relatively high (see Table 18) . For the 8:1 and 10:1 compression conditions, performance dropped severely. This result is similar to that

observed in the previous analyses.

Target obscurity significantly altered performance. Table J.8 shows

that only 11 obscured targets were identified correctly, whereas 116

unobscured targets were identified correctly. The distraction introduced by vegetation reduced the number of correct identifications by a

factor of 10.

The sun angle durij, the mission also significantly altered interpreter performance. If the imagery was taken when the sun angle was high,

- targct3 wcre correutly identified; with a low-;un-angle condition, only

42 targets were correctly identified. A possiole reason for this effect

is that target details were hidden by the more extensive shadows produced

by the low sun angle.

18
/ ---.--- _- -- - ---

The most striking thing about Table 18 is the number of zero entries

--in the two left-hand columns. Only 11 correct identifications were made

of obscured targets. The extremely small number of responses makes any

interpretation of the interactions involving obscured targets questionable.

duce Bandwidth compression level interacted with target obscurity to produce a significant change in interpreter performance (Table 19). However,

because there were so few correct responses for the obscured target con-

' . dition, this effect must be interpreted cautiously. Apparently, increased

bandwidth after 2 bits/pel had a greater detrimental effect on obscured

targets than on unobscured targets.

Table 19

Reporting Level I1: Number of Correct Identifications,

Target Obscurity Versus Bandwidth Compression Level (24-inch GRD)

Bandwidth ecmpression level

Target

obscurity 8+ bits/pel 2 bits/pel 1 bit/pel .8 bit/pe!

Obscured 4 6 0 1

Unobscured 44 35 17 20

Total 48 41 17 21

Although the target obscurity by sun-angle interaction was significant, again the interaction should be generalized cautiously because of

the small number of correct responses for the obscured targets. A total

of 11 targets were reported under the obscured condition, 8 for the highsun-angle condition and 3 for the low-sun-angle condition. Under the

unobscured condition, the frequencies are 77 and 39. A greater, detrimental effect of low sun angle occurred for obscured targets.

Reporting Level III. At this reporting level, the interpreter identified the type of target detected (e.g., tank, cargo truck, trailer,

self-propelled gun). This required the ability to identify additiona,

cues and signatures of the target that permit more detailed identification. Table 15 shows that for Reporting Level II, there were three

significant main eifects--bandwidth compression level, target obscurity,

and sun angle--and four significant interactions--bandwidth compression

level by target obscurity, bandwidth compression level by sun angle, target obscurity by sun angle, and bandwidth compression level by target

obscurity by sun angle.

19
Table 20 sho•:s the frequency of correct identifications presented by

bandwidth compression level versus sun angle-contrast-target obscurity. SThe large number of zero entries in Table 20 is, again, striking. Discounting marginal totals, of the 32 cells in Table 20, 21 cells are zero.

with such a large number of zeros, the analysis of these data may be

unstable, and all of the interactions cannot be validly generalized.

Bandwidth compression level was statistically significant. The

right-hand column of Table 20 shows the frequency of correct identifications by bandwidth level. This result s consistent with previous findings of this research and shows that there is a sharp decline in perform-

"ance between 2 bits/pel and 1 bit/pel.

Target obscurity had a significant effect: there were 37 correct

responses for unobscured targets, but only 2 correct responses for obscured targets. The interpreters had great difficulty in making correct

L identifications with the 24-inch GRD imagery when the targets were embedded

in vegetation.

Sun angle produced a significant difference in performance. With a

high sun angle, there were 31 correct responses; at a low sun angle, there

were only 8 correct identifications. This result is consistent with the

results at other reporting levels.

Table 21 presents the significant triple interaction and shows the

number of correct identification in each of the 16 possible categories.

Since only two obscured targets were correctly identified, this significant triple interaction probably occurred because one cell contained two

responses; i.e., there are too few observations to make a reasonable

interpretation.

Table 21 also can be used to examine the three two-way interactions

as well as the triple interaction. For the interaction between bandwidth

compression level and target obscurity, the values for each bandwidth

level can be determined by adding the entries for high and low sun angles S~under the obscured target heading and doinq the same for the entries under

the unobscured target heading. The number of correct identifications at

a bandwidth of 8+ bits/pel is two for obscured targets and zero at all

other bandwidth levels. For unobscured targets, the number of correct

identifications at a bandwidth of 8+ bits/pel level is 16; the numbers

are 16, 3, and 2, respectively, at the cther three bandwidths. It could

be argued that the drop off in performance associated with bandwidth compression occurred sooner with unobscured targe's than with obscured targets. Such an argume.it is questionable, because, again, too few obscured

targets were identzieile to give credibility to such an interpretation.

20
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00

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Eu U

4-- ) c

4ý4

C:C

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Table 21

Reporting Levcl III: Number of Correct Identifications,

Bandwidth Compression Level Versus Sun Angle x

Target Obscurity (24-inch GRD)

Obscured Unobscured

Bandwidth

compression High sun Low sun High sun Low sun

level angle angle angle angle Total

8+ bits/pel 2 0 11 5 18

2 bits/pel 0 0 14 2 16

1 bit/pel 0 0 2 1 3

.8 bit/pel 0 0 2 0 2

Total 2 0 29 8 39

The bandwidth compression level by sun-angle interaction can be

examined (Table 21) in a manner similar to that above. If the results

for the obscured targets were added to those for the unobscured, the only

change that would occur from the results with unobscured targets is that

the number of correct detections at 8+ bits/pel is 13 instead of 11. It

appears that with a low sun angle, the use of bandwidth compression

quickly reduces the number of correct identifications, but that some

bandwidth compression can be tolerated with a high sun angle.

The final two-way interaction is the target obscurity by sun angle

interaction. Here again, there are too few responses to make any reasonable interpretation.

Summary Across Reporting Levels

Combining these results across reporting 3evels leads to the following conclusions:

Bandwidth Compression. The number of correct target identification

is significantly reduced by bandwidth compression; the larqest dccreasle

occurred at a compression ratio of 8:1 (1 bit/pd) .

22
Sun Angle. Detection and identification of targets is facilitated

by a high sun angle. Sun angle interacted with bandwidth compression to

reduce the number of correct identifications under low sun angle, but

had little effect at low compression (4:1) under high sun angle. Although high sun angle is generally better, sun angle does not affect

detection of targets (Reporting Level I) under low-contrast conditions

for unobscured targets.

Target Obscurity. In the digitized imagery used in this experiment,

military targets surrounded by vegetation are extremely difficult to detect and identify.

Other Interactions. Inspection of these interactions revealed that

most involved target obscurity for which there were few responses at one

or both levels of the variable. With so few values, interpretation of

these interactions was considered tequous.

Summary Across GRD Levels

The results at each of the three ground resolutions are summarized

across the three parallel experiments, first in terms of right identifications, and then in terms of wrong identifications.

Right Identifications. The number of correct identifications is

summarized in Table 22 in terms of bandwidth compression ratio at each

GRD for each of the five levels of reporting. The 8-inch and 16-inch GRD

images were vertical photographs, and the 24-inch GRD images were oblique

photographs. However, the effect on interpreter performance produced by

the vertical/oblique dichotomy cannot be determined in this research.

The data in Table 22 are plotted in Figure 1, providing a set of

three curves for each reporting level--a separate curve for the 8-inch,

16-inch, and 24-inch GRDs. (No plot for Reporting Level V was made, since

data were available only for the 8-inch GRD.

In Figure 1, the bandwidth compression factor is plotted along a

logarithmic scale, and information extracted--number of correct responses--

is plotted along an equal division scale. The following is the rationale

for plotting the results for the 16-inch and 24-inch GRD imagery beginning

at 4:1 and 9:1 respectively, on the same bandwidth reduction scale as for

the 8-inch GRD imagery.

Analytically, there is a logarithmic relationship between bandwidth

and the information content of the imag4] Degradation of imagery by increasing the size of the GRD can be assumed to have an effect analogous

to that of bandwidth compression. If the original image has an 8-inch

(;16) dnd then is degraded photographically (by defocusing or other means)

to a 16-inch GRD, the degraded image reflects a change of 2:1 along the

width and length dimensions of the degraded image. In area, this is a

4:J. c)iarlge. By a similar argument, the 24-inch GRD imagery represents a

i iIIir -I rn, 1inqle(, or a 9:1 area change over the 8-inch GRD image.

23
as ID 1- 0

0. I l en In

4 (D co0 r4 0 '.0

N N -NN r

0 0)N N f1 L

-- 4

04

H~ 4 %D. 0 ýo NPC

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0 0 . 4 0 N '

u a) wl -d r N - 'N -4 Ix 0-4

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'44 0.\. ) I

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>4 H4 '9 '0 r

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CO '0o CO C

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E 4ý > 41 i -.

0 .-1 C

-44- J,

F3 0. 00 w

'.~ - N. N 0.24

The set of three curves for Reporting Level I is in the upper part

of Figure 1. For the 8-inch GRD curve, the 1:1 compression ratio shows

that the interpreters detected 108 targets, or 65% of those in the imagery.

At the 8:1 compression ratio, about 50% of the targets were detected. At

the 8:1 compression ratio for the 24-inch GRD curve, only 27% of the possible targets were detected. The deterioration of interpreter detection

performance is a joint effect of GRD and bandwidth compression.

The second set of three curves in the upper portion of Figure 1 is

for Reporting Level II--identification of the target class (e.g., tracked

vehicle). The 1:1 compression ratio for 8-inch GRD shows 96 correct identifications, or about 58%, and 17 correct identifications at the 8:1 compression ratio for the 24-inch GRD imagery, or about 9%.

The third set of curves in Figure 1 shows the number of correct responses for Reporting Level III. This level of reporting requires that

the interpreter designate the type of military target in general terms

(e.g., cargo truck). Performance at this level ranges from 48 correct

at the 1:1 compression ratio for 8-inch GRD imagery to 2 correct at the

10:1 compression ratio for 24-inch GRD imagery. Thus, the performance

range is from about 29% to 2% of the number of possible identifications.

The three curves at the bottom of Figure 1 are for Reporting Level

IV--identification by target type (e.g., 2-1/2-ton truck). Here the range

from highest to lowest performance is from 22 at the 1:1 compression ratio

for 8-inch GRD to zero for the 10:1 compression ratio for the 24-inch GRD

imagery. Target type identifications ranged from 13% to 0% of the number

of possible identifications.

Based upon these results, it appears that the utility of bandwidth

compression cannot be assessed without specifying the nature of the task

to be performed. For Reporting Level I, if a level of 50% correct detection performance were considered acceptable, then for 8-inch GRD

imagery all compression ratios would be satisfactory, as well as the

1:1 and 4:1 compression ratios for the 16-inch GRD imagery. For detailed

interpretation like that required for Reporting Level IV, performances

obtained in this research would be unsatisfactory at'all levels of GRD

and at all compression ratios.

In respect to the above performance figures, it should be noted that

the image interpreters participating in these experiments had little or

no previous experience with digitized imagery. The training/practice

period used in this research was too brief to provide the experience

level of an "operationally ready" interpreter. This lack of experience/

training depressed performance below what would be expected if the interpreters had received a reasonable amount of training and experience

in the interpretation of digitized imagery.

26
Wrong Identifications. Table 23 summnarizes the number of wrcnq identifications in the same format as that used for the number of right identifications. These data are graphed in the samne manner as the right-A

identifications and appear as Figuire 2 and Figure 3. Two figures are

used to make the different curves distinct. Fioure 2 shows the sets of1

curves for Reporting Levels 11 and IV. The alianment of the three curves

in each set is not as distinct for the wrong identifications as it was

for the right identifications. The separate curves for the three GRD

levels in a set haw'e bee-n labeled to indicate the reporting level represented. The three cuives in Figure 2 labeled Level 11 show that thereA AJ were relatively few wrong identifications--for the 8-Ainch G-prO (1 to 16),

for the 16-inch GRD (13 to 21), and for the 24-inch GRPD (17 to 23) -- but

the trend was for the niumber of wronq identifications to increase with

a reduction of image quali':v However, curves for Reportinq Level 1%

(Figure 2) show a consistent decline in the number of wronci icltýntifications with a reduction of image quality both by GRD and bandwidth compression--from a high of 37 misidentifications to a low of 4 misidentifications. Similarly, for Reporting Levels 111 and V%, the number of wrony

identifications drop-s steadily with image degradation (Figure 3)

Thus, it appears that in the more detailed inter:pretation associatced

withi Reporting Levels !IT, IV, V, the interp-reters were able to accurately

Judge the quality ot- rmaverv and idac tho frcquency c-_ their identifications as imaqe ciuali ty was reduced, thereby reducing thce number of wrono

identifications (but unfortunately also reducing thc nuinb-er ofrih ien

cificitions) .~ However, for Reportinc4 Lovel 1I (gross tarciet. clast, idenltification) , the interproters did nort judge the quality -f imdagery as

dccurately, and consequent] y produced more w.rong identifications as lnoefl

quality decreased either by GRPD, or bandwidth compression, Or both.

CONCLUSIONS

1. Bandwidth compression of dinitized imacer\' of various around

resolutions reduces the number of tarqets detected and identified (at

several levels of detail) by image interpreters. Although thiere is some

reduction in performance in the first level of compression (4;1), the

largest decrease is between compression ratios of 4:1 to 8:1.

2. ý;enerallv,, bandwidth compression reduces the number of wronel

taroet identifications made by imac-e interpreters.

3In t'ie training and practice period, the interpreters were inet3-ructed

to report onl1V LflOSe target ide~ntificati-ons where they wore "rcsitive"

of their identifications or where, at. least, the., felt them to be tile

'probable" iderzifit~aions.5 (Tho "Poss2.blý level of certainty was to

be eiiininated.) Those instructions appear in Appendix B. It is; possible

that this instruc:tion ma.Y'nhove reduced the number of wroma iderntfications.
SI I I I I

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If c

-, a

ccf / I .= C -

I / C- {ji II! _I

.1 1.2' -

C 

C

C

C

C

/ C C

C C

C C, C C C

C '7/

LC C I a C I

I

SL)'PI XJLLI.J O SUGIDtjUp1 DUO.IM 0 JqI!n3. Detection and identification of targets is generally reduced by

low sun angle. For the detection of unobscured targets under lowcontrast conditions, however, sun angle has no effect. (Analyzed only

for the 24-inch GRD imagery.)

4. The reduction in target identification due to bandwidth compression occurs sooner at low sun angles than at higher sun angles (4:1

low sun and 8:1 for high sun). (Analyzed only for the 24-inch GRD

imagery.)

5. A large decrease in performance occurs if the target is obscured (not in the open). Contrast, however, has no effect by itself

1 within the range used. (Analyzed only for the 24-inch GRD imagery.)

"6. Additional research is required to determine the effects of

bandwidth compression under typical operational conditions, that is,

those involving the search function and image interpreters better trained

on compressed, digitized images.

7. The interaction effects of bandwidth compression, sun angle

and target obscurity should be investigated more thoroughly under typical

A operational conditions, particularly for 8-inch and 16-inch GRD vertical

I imagery.

31
APPENDIX A

INTRODUCTION

Gentlemen, I am Harold Martinek of the Army Research Institute. I

am the data collection and analysis part of a research team composed of

image interpreters, engineers, human factors scientists, intelligence

personnel, and so forth, from several organizations such as the Electronics Command, the U.S. Army Space Programs Office, and of course, the

U.S. Army Research Institute.

Our purpose in this research is to make an initial determination of

the effect of a bandwidth compression technique on the intelligence information generated by image interpreters. As you know, one problem with

most imaging systems, particularly for mobile tactical targets, is getting

the image from the platform to the interpreter in a timely manner. With

some platforms it is a major problem. Electronic transmission is an

answer but does have some problems associated with it--one of which we

are looking into with this research; that is, the efficient use of bandwidth. In this electronic age we live in, bandwidth reduction is of

critical concern to the Department of Defense. By mysterious mathematical theory, electronic black boxes, and computerized means, it is possible

to reduce the bandwidth required to send an image. This bandwidth compression technique, while saving bandwidth, does affect the interpretability of the image. The questions are, how much and under what

conditions?

An initial attempt at answering these questions is what we will be

doing today and tomorrow morning. You will be asked to read out image

chips varying in the amount of bandwidth compression used, in resolution,

in the number and type of vehicles portrayed, in contrast, in the sun

angle, and in the amount of vegetation around the target. Naturally,

like all imagery, many other factors are present which affect interpretability, but they are not of concern in this research. Nor are we interested in your performance as an individual but only in how these variables affect interpreter performance.

ARE THERE ANY QUESTIONS AT THIS POINT ON THE PURPOSE OF OUR

RESEARCH?

Today, we'll look at the target list, American equipment Minikey, and the report form you will be using. Then we will review the

imagery to give you practice with representative samples of all the

resolutions, bandwidth compression levels, and target types you will

be working with tomorrow during the actual data collection effort.

33

- ,PRECEDING PAGE BLANK

/ / // r I I I...........
APPENDIX B

TRAINING INSTRUCTIONS

To help insure objectivity in this research, I want you to use only

the words or numbers in this Vehicle Target List when reporting targets.

We have found this procedure very helpful in past efforts to objectively

evaluate the reports consistently. Note that there are five categories

or columns of targets, going from the very general to the very specific.

The fifth column refers to numbers on the U.S. Equipment Mini-key which

you'll receive shortly. Each number is paired with a picture of a vehicle--the name, model number, and measurements are given. The group of numbers on one line in Column V, defines the word in Column IV on the

same line. That is, on the first line number 3, 4, or 5, whatever they

are on the Mini-key, define what an APC is for the purposes of this study.

Similarly, on line 2, the numbers 1 and 2 or some other vehicle similar

to these define the term "APC Other." Going to Column III, the term

"APC Type" means the target is either an APC or an "APC Other." Again,

going to Column II, Tracked Vehicle is defined by Column III, i.e., APC

Type, SP Arty, Tank, or Recovery Vehicle. Column I is the most general

target category, i.e., Military or Nothing. The latter could indicate

that there was nothing on the picture or that there was an unidentified

object that you are not sure enough about to report it as a military

object.

In using this list you should always try to use the most specific

term you can--if you can label an object as probably or positively an

M48 Tank you would find the appropriate number on the Mini-key and write

the number down. Perhaps you know it is a tank but cannot interpret it

any finer--then report the word "TANK." Do not report "possible" objects--only probable or positive. That is, if the object is a "possible"

M48, but a probable Medium Tank report Medium Tank. As you go from image

to image and across different levels of resolution, try to keep the same

standards of reporting--never reporting "possible" targets.

Use of several levels of target names like these will allow us to

determine how much information can be extracted from an image of a particular type. Then we can pick the compression level which will allow

the interpreter to provide the information the commander requires. In

a sense, you will be setting the materiel specifications for future

image systems.

ARE THERE ANY QUESTIONS?

The following steps were followed during this first day of the experiment. These items are not a part of the instructions given but were

used as notes to keep the experimenter onr'course. They are listed here

for record purposes only:

35

I4EX.N Fit ~L~~
- Review Target List

- Hand out Mini-key

- Review Mini-key (allow 15 minutes)

- Practice set for 8-inch Resolution

- Instruct participants to:

int :et 7 to 8 targets and check answers using scoring key,

chec. wrong answers with Mini-key,

interpret different set of images (labeled I to IV).

Ar - I )

- I

12

I3

,I:t S. ..• ... .... )
AFC [ 3, 4, 5

ApC Type C1, 2, other ApC othe

Sp Gun 6, 10, 12, 13, 14

SP 7, 8A 9, 1, 15

Tracked SP HOW

Vehicle

Tank Medium TK 16, 19

Heavy TK 17 18

ReoeyM578 Chassis 20, 21, 22 S"IRecovery 23, 24

M Vehicle Not M578 2 • iM 

3 , 172 32

Semi Truck Semi-Fuel 27, 28, 31 32

With Trailer Sem-Cargo 25, 26, 29,30, 33-36

' ! 

37 , 38, other

Heavy Truck 5 Ton + 37, 38, other

21⁄2 Ton 44, 46, 48, Other

Tank Truck Water 40, other

Tanuel 42, Other

Vehicles 

4 te

A 3/4 Ton Truck 3/4 Ton Cargo 40. other

R,3/4 Ton Other 51, 53

1 o 1/4 Ton Cargo 56, Other

Y 1 T r1/4 Ton Other 54, 55, Other

Trailer Caro Trl 47, 50, 57

Special Trl 39, 41, 43, 45

Trailers Gun 92, 94, 95, 99 1

Artillery Arty Towed 93, 904 901 , 9

& Aircraft Missile 96, 97, 98

(TAA) il 98Mis 

Aircraft Fixed Wing Model 0

Rotary Model ft

Earth Moving Tracked FM 85, 87

Wheeled EM 76,.83, 84, 86

Engineer Tracked Bridge 73, , 75

Equipment Bridging Wheeled Bridge 72, 82, 90

Engineer Trks 77, 80, 81, 88

special Truck Wrecker 58, Other

STrucks

N (Or Unknown) 

j

T

1

N 

3

IG
IMAGE TRANSMISSION STUDY -

Photo Group

Photo Set Start End Photo Set Start End -_

b Photo # Target ID Remarks Photo 4' Target ID Remarks

1.__ -- _ __ _ __ _I

__ _ iIi _____ I ________

I-- 4ii

i i_____________ I I 

_ _ _ _ _ Il _ _ _ _ _

__i1 _It _t -v---

I I I

S. . . . . . _ _ . . . . . . . . . . . ._.._ . . _ . . . . . . . .- 1 . . . . . . . . . . . . . . . ...
II

I • Practice 8-inch GRD Scoring Key

I+I

Practi Scoring Level

- Photo # II III IV V Remarks

921 3 Wh Veh Hvy Truck 5T+ 37 M55

Hvy Truck 2 1/2 T 44 M109

IHvy Truck 2 1/2 T 48 M.36

A 922 2 Wh Veh 3/4 T Truck 3/4 T other 51 Commo Shelter

3/4 T Truck 3/4 T other 53 M43

923 Eng Equip Special Truck Trk Wrecker 58 M62 SEng Equip Earth Moving 1'h EM 83 Loader Schoop MTZ

924 W'h Veh Tank Truck Fuel 42 M449

ATT Trailer Cargo Tlr. 47 1,104

Eng Equip Earth Moving Wheeled EM 76 Scraper 11vv w/Trac

925 Track Veh SP Arty SP Gun 10 M140

Wh Veh Semi-Trk Semi- Cargo 35 152 2

ATT Arty Towed Cul 95 120mm

926 2 ATT Arty Towed Missile 96 M387E1 (U4rosse)

Arty Towed HOW 100 Ml15

927 3 Track Veh Tank Heavy Tk 17 M60

Tank Med. Tk 19 M48 Recovery Veh M578 Chassis 21 M578

928 3 Track Veh APC Type APC 3 M75

APC Type APC 5 M159

Recovery Veh Not 11578 24 M188

929 2 Track Veh SP Arty SP HOW 8 M37

S11 Arty SP Gun 13 1I107

930 Track Veh SP Arty SP Gun 14 M53

I

Ii

I3
PRACTICE 16-INCH GRD SCORING KEY

Sc=,ring Level

Photo #/ it III IV VReak

* 911 2 Wh Veh Hvy Truck 21/2 4 M37

3/4 T Trk 3/4 T Cargo 49 M37 4 .

912 2 Wh Veh 1/4 T Trk 1/4T 52 ,M36

11 4/4 T Trk 1/4 T Other 54 M170

913 2 Eng Equip 2 Earth Moving EhM 84 Grader . Track ED 85 Dozer

914 Wh Veh Tank Trk Water 40 H5C

2 ATT Trailer Special Trl 41 N107

Trailer Special Trl 43 Tk Fuel

915 3 ATT Trailer Cargo Trl 57 M100

Arty Towed HOW 93 M101

Arty Towed HOw 1001 m114

916 Track Veh Tank Med k 16 M41

SATT Arty Towed Missile 97 M386 (1-)

917 3 Track Veh Tank 1ivy 1k 18 M103

Recovery Veh M578 Chassis 20 M578 (Chassis)

Recovery Veh. M578 Chassis 22 H1578

z~ n o h er IT RA C H igh Speed

918 3 Track Veh APC Type APC Other 1 1C1 hpe

APC Type A4C Other 2 1013

APC Type APC 4 Ml13

919 3 Track Veh SP Arty SP HOW 7

SP Arty SP 1OW 9 lO8

SP Arty SP HOW 11 N110

920 Track veh SP Arty SP HOW 15 M55

I

L4(
- I PRACTICE 24-INCH GRD SCORING KEY

Scoring Level

t Photol/ II III IV V Remarks

S901 4 W6h Veh Tank Trk 21⁄2T Wtr 40 M50

Tank Trk 2;T Fuel 42 M49

Heavy Trk 21⁄2T 4/, m109

Heavy Trk 21⁄2T 46 M35

902 4 Track Veh APC Type APC Other 2 M106

APC Type APC 5 M59

SP Arty SP Gun 13 M107

SP Arty SP Gun 14 M53

0 903 4 Wh Veh Semi-Trk with Semi-Cargo 26 MI5 (W Tank)

Trailer

Sc' ,I-Trk Semi-Cargo 30 MDL Sty 620

3/4T Trk 3/4T Other 51 Commo Shelter

4T Trk •T Cargo 56 1138

904 4 Track Veh Tank Med. Tk 16 M4i

Tank" Heavy Tk 18 M103

Tank Med. Tk 19 1M48

Recovery Veh M578 Chassis 22 M578

"905 Eng. Equip Earth Moving Wh EM 84 Grader

Eng. Equip Earth Moving Track EM 85 Dozer

, ATT Arty Towed HOW 93 11101

ATT Arty Towed HOW 101 I114

906 4 ATT 4 Arty Towed Gun 95 120mm

Missile 96 Lncher (LaCrosse)

Missile 97 M386 (HJ)

Gun 99 M59 (Carriage)

907 4 Eng Equip Bridging Tracked-Bridge 73 M48C

Earth Moving Wheeled EM 76 Scraper Hvy w/Trac

Special Trk Eng Trk 80 Dump M59

Earth Moving W'h EM 83 Loader Scoop MTZ

908 4 Eng Equip Earth Moving Wheeled EM 76 Scraper lIvy w/Trac

- Special Trk Eng Trk 80 Dump M59

Earth Moving Tracked EM 87 Crane Shove] I Special Trk Eng Trk 88 M29C

909 4 ATT 4 Arty Towed HOW 93 M1110

Misslle 96 La Cros:

Missile 97 M386 (1i0)

HOW 10] m114

910 Track Veh Recovery Veh M578 Chassis 22 M578

Track Veh Recovery Veh Not M578 24 M88

Wh \eh Semi-Trk w/Tr] Semi-Cargo 34 M127

Wh Veh 3/4T Trk 3/4T Other 51 Van Commo Shelter

41
| I

* APPENDIX C

TEST PROCEDURES AND IMAGERY DESCRIPTION

You will be interpreting only 40 small image chips today at each of three resolutions for a total of 120 chips. Essentially, the imagery is

the same as the practice imagery. Since each chip covers, on the average,

only a 100 x 100 foot square on the ground, it can contain only a few

targets--say from zero to about six or seven. I estimate the whole job

should take 3 hours, but 4 hours have been allocated. As with the practice imagery, within each resolution the bandwidth compression level used

will vary--thus some images within a group will be harder to interpret =

4 than others. Similarly, the contrast and sun angle vary within each

group. This imagery is different from thF practice imagery in that some

targets are in the open while others are partially obscured. The scale

varies from 1:1,000 to 1:3,000, and scale level will be ýurnished to you

along with the photos. Two of the groups of images are vertical and one is oblique--additionally, the oblique is at the poorest ground resolution.

The foraat is the same as the practice imagery.

Remember that some of the imagery will be quite poor, and perhaps

even impossible to interpret. Just try to interpret it using the most

detailed description you can from thc target list but not reporting anything at the "possible" level.

ARE THERE ANY QUESTIONS?

NOTE: Allow approximately 50 minutes, followed by a break.

2

43 -.

___ ~~AiWuAJOT FJh
S~APPENDIX D

S~IMAGE MATRICES AND TARGET LISTS

Simulation Output Nomenclature Explanation

Each image mosaic is annotated as shown in Figure D-1 below. The

top row is a mosaic identification number. The ten numbers in the next

four rows correspond to image identification numbers assigned to the ten

images in the mosaic. At the bottom of each mosaic is an experiment number 501-XXX. The mosaic number can be used to locate other pertinent information in Table D-l, such as resolution, scenario group, and bit

rate. This information can be used in conjunction with the three experimental matrices given in Table D-2, Table D-3, and Table D-4 to

determine sun angle, contrast, and whether the target is obscured or

unobscured. Table D-5 to Table D-7 show the targets within each image

and how they were scored at each reporting level.

Image Image 1 Image 3 5 7

Image Image Image

9 6 1

Image Image Image

10 8 2

Image

4

000 000 000 >- Mosaic Number

003 005 007"

009 006 001

, • Image Number

010 008 002'

004

Exp. / 501-XXX

Figure D-1. Image mosaic annotation example.

45

"" ' 9 CEDING PAGE BLANK
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r- 0 0)c ý4 ý - -

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co ID z 1 11 o3 o1 T D11 0I 0'T :)O

-4 N I N N N 4 -
In W 

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41 Q) Q w

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Table D-5

Scoring Key for 8-inch GRD Imagery

Group 1

Photo # II III IV V Remarks

45 Tracked Tank Medium 19 M48

54 Two Tracked 2 SP Arty 2 Sp HOW Two '15's M55

57 Wheeled 1/4 T Trk 1/4 T Cargo 56 M355 or M38

58 Two Wheeled 1/4 T 1/4 T Cargo 56

3/4 T 3/4 T Cargo 49 M37

63 Two Wheeled Cargo Trk 2-1/2 T 46 or 48

Tank Trk Fuel 42 M49

64 OMIT

67 Two Wheeled 1/4 T 1/4 T Cargo 56 M355 or M38

Cargo Trk 2-1/2 T 46 or 48 M135 or M211

68 Two Trl, Two Trailers 2 Special Two 41's M107 or M149

Arty and AC Trk

7 3 . .. .. .. .. .

7 9 . .. .. .. .. .

Group 2

43 Five Tracked Five APC Five APC Three 3's

Type Two 5's

1 Wheeled Cargo Trk 2-1/2 T 46 or 48 OK M135 or

M211

48 Tracked APC Type APC 4

52 1 Tracked SP Arty HOW 9

1 Wheeled 1/4 T Trk 1/4 T Cargo 56 M355 or M38

65 Trl, Arty, AC Arty Towed. HOW 100 M115

66 Trl, Arty, AC Arty Towed HlOW 101 M114

69 Two Trl, Arty, Two Aircraft Two Fixed Two L19

AC Wing

70 1 Trl, Arty,AC 1 Trailer Cargo Trailer 57 MI00

1 Wheeled Veh 1 3/4 T 3/4 T Cargo 49 M37

71 2 Trl Arty,AC Two Arty Two HOW Two 93's MI01

Towed

1 Wheeled Cargo Trk 2-1/2 T 46 or 48 M135 or M211

74 ......--..

7 8 . .. . -- .. .. .

aCategory I score is number of vehicles in category II. In addition, score as

correct words such as military, vehicles, unidentified vehicles, military objects, or any higher category words.
Table D-5 (continued)

Group 3

SPhoto f II III IV V Remarks

42 Tracked Tank Medium Tank 19 M48

44 Three Tracked Three Tanks Three Medium Tk Three 16

47 Five Tracked Five 'ldnks Five Medium Tic Five 19

49 Tracked SP Arty SP HOW 9 108

53 Tracked SP Arty SP HOW 9

56 Tracked SP Arty SP HOW 9

Wheeled 3/4 T 3/4 T Cargo 49 M37

Trl, Arty, AC Arty Towed HOW 93,100,101

59 Wheeled Cargo Truck 2-1/2 T 46 or 48 Civ Veh is

Score one extra correct for Category I only. right for Cat I

62 Two 1 Cargo Trk 2-1/2 T 46, 48 M34,M35,M-135,M211

Wheeled 1 3/4 T Trk 3/4 T Cargo 49 H.37M

76 ..-- -- --

80 ...

Group 4

41 Tracked Tank Medium Tk 19 M486

46 Trazked Tank Medium Tk 19 '148

5D Tracked SP Arty OP HOW 9 M108

51 Tracked SP Arty SP HOW 9 1108

Wheeled 3/4 T Trk 3/4 T Cargo 49 '.137

55 Tracked SP Arty SP Gun 13 Y1107

60 OMIT O'MIT OMIT OMIT --

61 Two 1 3/4 T Trk 3/4 T Cargo 49

Wheeled 1 Cargo Trk 2 1/2 T 46 or 48

72 C,:-I T OM I T O.iT OMIT --

-I - I 7 7,. ... .... .. - .

I
/--- - •~-- -_•_•

Table D-6

Scoring Key for 16-inch GRD Imagery

Group 1

Photo # II III IV V Remarks

85 Tracked APC Type APC 4 M113

87 Four Tracked 2 APC Type 2 APC Two 3 .,75 Parts of

2 Tank 2 Medium Tk Two 19 M48 Tanks

"90 Two Tracked 2 SP Arty 2 SP HOW Two 16 M55

91 Tracked SP Arty SP HOW 9 M108

97 Wheeled Cargo Trk 2-1/2 Ton 46 or 48 M34,iM35

100 Three Wheeled 1-1/4 Ton Trk 1/4 Ton Cargo 56 36

1-3/4 Ton Trk 3/4 Ton Other 53 Ambulance

1-Cargo Trk 2-1/2 Ton 46 or 48 m135

102 Two Wheeled 1-1/4 Ton Trk 1/4 Ton Cargo 56 X,38

l-Carao Trk 2-1/2 Ton 46 or 48 Same imace

as 6

ill Two Wheeled 1-3/4 Ton Trk 3/4 Ton Cargo 49 M37

1-Cargo Trk 1-2-1/2 Ton 48 M136

Truck

Two Trl, Arty 2-Trailers I Special Trl Not Listed M139

AC, TAA 1-Arty Towed I Cargo Trl Not Listed MIOI(

1 Misoile One 97 Honest John

120 .......... -

114 ..........

Group 2

86 Four Tracked Four APC Type Four APC Three 3 m75

One 5 M•59

92 Tracked Sparty SP HOW 9 X1108

99 Two Tracked Two Tanks 2 Med TK Two 19 Out of picture

101 Three Wheeled Two 1/4 Ton Two 1/4 Ton Two 56's M36

Trk Cargo

One Cargo Trk 5 Ton 37 or 3 M.S,6- v55-...41

103 Two Wheeled Two 1/4 Ton Two 1,12 Ton Two C) 'sE M38

Trk Cargo

Score two extra rights for Category I o:dy.

105 Trailers Art'v Towed i OW 131 Same as

Arty & A/C image 66

106 One Tracked SP Arty SP HOW 9 I1-8

Two Wheeled 1-1/4 Ton Trk 1/4 Ton Carqo 51) Trk's Same as

i macr- 102

1-Cargo 2-1/2 Ton 46 or 48

112 OM IT OMI4T OXIT OMIT OMI T

1155
Table D-6 (continued)

Photo # IV V Remarks

Group III

81 Three Tracked 2 Tank 2 Medium Two 19 M48

1 Recovery 1 Not M578 One 24 M88

82 Tracked APC Type APC 4 M113

83 Two Two 2 Medium Two M48

Tracked Tanks Tanks 19

93 Tracked SP Arty SP HOW 9 MI08

94 Tracked SP; A ty SP HOW 9 MI08

95 1-Wheeled 1/4 Ton Truck 1/4 Ton Cargo 56 M38 or M355

1-Trackel SP Arty SP HOE 9 Same as 52

104 OMIT OMIT OMIT OMIT OMIT

108 OMIT OMIT OMIT OMIT OMIT

117 ....

116 ..........

Group IV

84 TWo 2 2 Medium Two

Tracked Tanks Tanks 19

88 Two Two Two Two

Tracked AFC Type APC 3 M75

89 Tracked SP Arty SP HOW 9

96 Tracked SP Arty SP HoW 9

98 Wheeled Cargo Trk 2-1/2 Ton Trk 46 or 48

107 Trailer Trailer Cargo 47

Arty & A/C Trailer

109 Trailer 1 1 Fixed Wing L19 Bird Dog

Arty A/C Aircraft

. 110 2 Wheeled 3/4 Ton Trk 3/4 Ton Ca~go 49 M37

1/4 Ton Trk 1/4 Ton Cargo 56 M38

1 Trl, Arty, Trailer Cargo Trl 57 MIo0

* AC

113 -- - ..

118 - -- --

_ _ _ _ _ _ _........
• • - • - - •--- -- . • -- , -•: - - 2•--- - - - - - - - - - - • -

Table D-7

Scoring Key for 24-inch GRD Imagery

Photo # II III IV V Remarks

.1 Group I

1 Eng Equip Special Truck Eng Trk 80 M59

SWh Veh Heavy Truck 2-1/2 Ton 46 1.35

*5 Eng Equip Earth Moving Wh Em 84

Track Veh SP Arty SP Gun 13 M107

9 Track Veh Tank Medium Tank 19 M48

TAA Arty Towed Missile 96 M387

13 W--- h Veh- Semi-Truck-- Semi-Fuel 32 M30

TAA Arty Towed Missile 96 M387

17 TAA Arty Towed HOW 101 M1114

Track Veh APC Type APC 2 MI06

* 21 Wh Vei Semi-Truck Semi-Cargo 34 14127

with Trailer

TAA Arty Towed Gun 99

25 Eng Equip Earth Moving Wh Em 83

Wh Veh 1/4 Ton Truck 1/4 Ton Cargo 56

29 Eng Equip Earth Moving Wh Em 76

Track Ven Recovery Veh M578 Chassis 22

34 ....

35 ....
~ -1~ t=v--/ ~ ---- ~- - ----=-____--- =- -

- - _- --

J - Table D-7 (continued) A

Photo # II III IV V Remarks j

Group II

2 Wh Veh Semi-Trk Semi-Cargo 34 M127

w/Trailer

TAA Arty Towed Gun 95

6 Eng Equip Earth Moving Tracked EM 85

Wh Veh 3/4 Ton Trk 3/4 Ton Other 51

10 Eng Equip Bridging Tracked Bri.7 M488

Track Veh Recovery Veh Not M578 24 M88

14 Track Veh APC Type APC 5 1.59 i

TAA Arty Towed HOW 93 M101 I1B Track Veh SP Arty SP Gun 14 M53

Eng Equip Earth moving Tracked EM 87

22 TAA Arty Towed Gun 99 M59

Track Veh Tank Med Tk 16 1.141

26 Wh Veh Tank Truck Water 40 M50

TAA Arty Towed Missile 97 M386

30 Wh Veh livy Truck 2-1/2 Tnn 46 M35 5

Eng Equip Special Trk Eng Trk 88 M29C I

33 Omit 1 Military .. -

f ~Obiect

36 "-"

i-i

• 55
Table D-7 (continued)

F Photo # II III IV V Remarks

Group III

3 Track Veh Tank Hvy Tank 18 M103

TAA Arty Towed HOW 101 M114

7 TAA Arty Towed Missile 97 M386

Wh Veh Tank Trk Fuel 42 M49

11 Eng Equip Special Trk Engineer Trk 88 M29

Wh Veh Heavy Trk 2-1/2 Ton 44 1.1109

15 Track Veh SP Arty SP Gun 14 M53

Eng Equip Earth Moving Wheeled EM 84 A

19 Wh Veh 3/4 Ton Trk 3/4 Ton Other 51

Eng Equip Earth Moving Track Veh 85

S23 Eng Equip Earth Moving Wh EM 84

Track Veh Recovery Veh M578 Chassis 22 ,.,578

27 Wh Veh APC Type APC 5 .59

TAA Arty Towed HOW 93 MI01

31 TAA Arty Towed Gun 95

Wh Veh Semi-Truck Semi-Cargo 30

with Trailer

37 __

40 Omit 1 Military --

Object

56

- .
Table D-7 (continued)

Photo # II III IV V Remarks

Group IV

4 Eng Equip Earth Moving Wh EM 76

Track Veh Recovery Veh M578 Chassis 20

8 Track Veh APC Type APC Other 2 M106

TAA Arty Towed HOW 101 M114

12 Wh Veh Semi-Trk Semi-Cargo 34

w/Trailer

Track Veh SP Arty SP Gun 14 M53

16 Eng Equip Earth Moving Wh Veh 83

Wh Veh 1/4 Ton Trk 1/4 Ton Cargo 56

20 Wh Veh Tank Truck Water 40 M50

TAA Arty Towed Missile 96 M387

24 Wh Veh Semi-Truck Semi-Cargo 34 M127

Eng Equip Spec Trk Eng Trk 80 M59 A

28 Eng Equip Earth Moving Track EM 87

Track Veh SP Arty SP Gun 13 M107

32 Track Veh Tank Med Tk 19 M48

1TAA Arty Towed HOW 93 MI01 V 3 8 . .. .. .- -

39

57

57J
APPENDIX E

CONTROL VARIABLE RESULTS

So as not to burden the results section of the report with a discussion of control variables, Appendix E has been prepared. Significant differences produced by these independent variables are described

here for the sake of completeness.

Eight-Inch Ground Resolution Experiment

Right Identification Scores. Table E-1 shows the analysis of variance summary for the right identification scores by independent variable

versus reporting level. Independent variables that significantly affected

interpreter performance are indicated. Bandwidth compression level has

been discussed in the body of the report and will not be given here.

Table E-1

Analysis of Variance Summary for Right

Identifications, Independent Variables

Versus Reporting Level (8-inch GRD)

Reporting level

Independent variable I II III IV Va

Groups

Periods

Bandwidth compression

level **

Scenario   **  **

Residual

"*Significant at the .01 level.

a Insufficient data.

59
i

Table E-2 shows the number of right identifications per scenario by reporting level. That scenarios differ significantly among themselves

is not unexpected. The eight chips scored in the ten image chips making up a mosaic comprise a scenario. The total number of targets, target size, target type, terrain characteristics, and so forth were controlled subjectively to make the four scenarios similar but they were not con- sidered to be physically equal. Therefore, the number of correct responses differing significantly among scenarios at each of the four re- porting levels (where there were sufficient responses to justify analysis) demonstrates the fact that the scenarios are not equivalent. In terms of interpreter performance in this study, it appears that if the scenarios

were ordered in terms of difficulty they would range from S2, the easiest, followed by S4 , then S3 , and finally Sl, the most difficult. For the number of right identifications there was no significant difference among groups for Reporting Levels I through IV. Reporting Level V performance

was not tested due to lack of data.

Table E-2

Number of Right Identifications, Scenario

Versus Reporting Level (8-inch GRD)

Reporting level

Scenario I II III IV V

S1 86 62 28 9 3

S2 109 86 30 25 12

S3 90 76 37 19 5

S4 102 84 46 25 10

Wrong Identification Scores. Table E-3 gives the analysis of variance summa:-y data for independent variables versus the different levels of reporting. Three variables were significant--groups, bandwidth, com- pression, and scenarios. Table E-4 gives the number of wrong identifications made by the four groups at each of four reporting level3. Re- porting Level V was associated with a significant variation in the

number of wrong responses producea by the groups. Groups 3 and 4 produced almost three times as many wrong identifications at this scoring level than did Groups 1 and 2. The groups of interpreters had been sub- jectively matched for ability by their supervisors arid the Finding tihat

they are not equal in this one case indicated that the subjective equating of the groups was not perfect.

60
Table E-3

Analysis of Variance Suumnary for Wrung

Identifications, Independent Variables

Versus Reporting Level (8-inch GPD)

Reporting levels

Independent variables 1a I III IV V

Groups

* Periods

Compression levels - *

Scenarios - ** ** * **

Residual

*Significant at the .05 level.

**Significant at the .01 level.

aInsufficient data.

Table E-4

Number of Wrong Identifications, Groups

Versus Reporting Level (8-inch GRD)

Reporting level

Groups Ta II III IV V

G - 20 19 18 14

1

G2 - 9 23 21 17

G 3 - 15 41 46 51

G4 - 8 19 38 45

aInsufficient data.

61j
Table E-5 lists the number of wrong identifications by scenario and

- Yeporting level. As for the right identifications t~e number of wrong

identifications differs significantly amon.. sce'drios for each of the reSporting levels. This is not unexpected sincc the scenarios were not

equated in terms of the physical characteristics of the images involved.

:xcept for Reporting Level II, S again appears to be the easiest

scenario.

Table E-5

Number of Wrong identifications, Scenario

Versus Reporting Level (8-inch GRD)

Reporting level

Scenario 1 a II III IV v

s - 4 16 32 35

S2 29 13 14 12

S 9 52 44 46

4 - 10 21 33 34

a Insufficient data.

"Sixteen -inch Ground Resolution Experiment

Right Identification Scores. Table E-. gives the analysis of variance summary for the right identifications by independent variables versus

reporting level. All of the independent variables were associated with

significant differences at one or more of the reporting levels. In addition there was a significant residual found for the fir-st reporting iev-1l

indicating that there may be interactions among the independent variabl.

Table E-7 shows the number of riaht identifications for the four

groups of interpreters at the various reportini levels. At Peporting

Level ITI, the performance of thc qroups differed significantly. .roup

4 made mariy more correct identifications than did any' of the other tiree

groups. As previously mentioned for the 8-inch experiment, Aroups had

been subjectively equated by their supervisors so that this sionifiua:nt

diffe'rence is rnot startling.
[i I

Table E-6

"Analysis of Variance Summary for Right iK - Identifications, Independent Variables

Versus Reporting Level (16-inch GRD)

Reporting level

Independent variables I II III IV Va

* Groups ** -

*< " , Periods * -

Bandwidth compression

level ** ** ** * -

Scenaric ** ** -

"Residual *

*Significant at the .05 level.

"*Significant at the .01 level.

aInsufficient data.

Table E-7

Number of Right Identifications, Groups

Versus Reporting Level (16-inch GRD) 'A

Reporting level ___

Group 1 1 111 IV Va

78 46 10 5 -

G2 80 50 12 4 -

G63 37 12 6 -

C6., 3C 1"7 "4 4

"Ii~sur ficlenlt data.

63
• J -----... . . - . . .

Table E-8 shows the number of right identifications for the four

work periods in the study for each of the reporting levels. At Reporting

Level III, performance differs significantly among the work periods.

There were fewer correct responses in the first period and many more in

-the fourth period, indicating that there may have been a practice effect.

That such an effect should be evident at only this one reporting level

out of three experiments suggests that this may be a chance occurrence.

Table E-8

Number of Right Identifications, Periods

Versus Reporting Level (16-inch GRD)

Reporting level

Period I II III IV Va

P 1 79 45 9 a -

P2 70 41 14 5 -

P3 79 52 14 6 -

P P4 79 58 27 13 -

F Iansufficient data.

Table E-9 gives the number of correct identifications by scenario

versus reporting level. Scenarios differ significantly for the first

three reporting levels. As was argued for the 8-inch experiment, the

scenarios were made similar but they could not be made identical for

all image and target variables. That the scenarios differ significantl/

among themselves in terms of the number of correct responses made is

evidence of their lack of equality.

Wrong Identification Scores. None of the control variables was associated with a significant difference in performance. The bandwidth

compression variable was the only independent variable for which there

was significance. That variable is discussed in the body of the report.

Twenty-Four-Inch Ground Resolution Experiment

Right Identification Scores. None of t.he control variables was

associated with a significant difference in performance.

04 K- _
j : Table E-9

Number of Right Identifications, Scenario

Versus Reporting Level (16-inch GRD)

Reporting level

Scenario I II III IV Va

S 65 42 14 9 -

S 86 57 27 11 - 2

S53 45 30 8 4 -

S4 1il 67 15 8 -

ainsufficient data.

wrong Identification Scores. None of the independent variables

was associated with a significant difference in performance at any

reporting level.

65

65
APPENDIX F

SIGNIFICANCE TESTS USING THE NEWMAN-KEULS METHOD

For each situation in which the bandwidth compression variable produces a significant change in interpreter performance, mean performance

at each of the four levels of the bandwidth compression variable was

tested using the Newman-Keuls Method (5% level of confidence) to determine which of these levels significantly affected performance.

Eight-Inch GRD Experiment, Right Identifications

At Reporting Level II, bandwidth compression was associated with

significant variation in interpreter performance. Mean performance at

all four reporting levels was significantly better at the 8+ bits/pel

level than performance for any other three bandwidth compression levels.

Any amount of bandwidth compression significantly degrades performance.

At the .8 bit/pel level, performance was significantly better than

that at 1 bit/pel. This result was contrary to expectation.

Eight-Inch Experiment, Wrong Identification

At Reporting Level III, bandwidth compression differences significantly affected interpreter performance. The 8+ bits/pel and the .8

bits/pel levels were both found to. have significantly more wrong responses than either the 2 bits/pel or 1 bit/pel level.

Sixteen-Inch Experiment, Right Identification

Bandwidth compression significantly affected performance for Reporting Level I through IV. Differences for each reporting level are

described separately.

"* Reporting Level I: At the 8+ bits/pel and the 2 bits/pel levels,

mean performance was significantly better than at 1 bit/pel

and .8 bit/pel.

"* Reporting Level II: At the 8+ bits/pel and the 2 bits/pel levels

mean performance was significantly better than that at 1 bit/pel

and .8 bit/pel.

"* Reporting Level III: At 8+ bits/pel, performance was significantly better than that at the ekther three bandwidth compression

levels. Additionally, mean performance at the 2 bits/pel level

was significantly better than that at 1 bit/pel and .8 bit/pel.

67

PRECEDING PAGE BLANK
* Reporting Level IV: At the 8+ bits/pel level, mean performance

was significantly better than that at the 1 bit/pel level only.

For the number of right identifications, performance did not drop

significantly with bandwidth compression before an 8:1 compression ratio

was reached. This performance followed t pectations as lowered perform- - ance was associated with greater compression. At Reporting Level IV, one

inversion occurred, with performance at I bit/pel slightly below that at

.8 bit/pel.

Sixteen-Inch Experiment, Wrong Identification 3,

Bandwidth coimprcssion level produced significa7,t differences in interpreter performance for Reporting Levels IV and V.

9 Reporting Level IV: At the 8+ bits/pel level, interpreters made

more wrong identifications than at the 1 bit/pel and .8 bit/pel

levels.

o Reporting Level V: At the 8+ bits/pel level, interpreters made

significantly more wrong identifications than at any of the other

three bandwidth compression levels.

Twenty-Four-Inch Experiment, Right identifications

Bandwidth compression level was associated with significant differences for Reporting Levels 11, III, and IV.

* Reporting Level II: The 8+ bits/pel and 2 bits/pel compression

levels were associated with significantly better performance than

were the 1 bit/pel and .8 bit/pel levels.

* Reporting Level III: The 8+ bits/pel and 2 bits/pel levels were

associated with performance means that differ significantly from

those obtained at 1 bit/pel and .8 bit/pel.

* Reporting Level IV: At 8+ bits/pel, mean performance was significantly better than for the other three levels.

68
o;STRItB UT IONj

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70