Analysis of BRDF/BTDF for the texture
representation of woven fabrics based on theimpression-evaluation model
Lisa ParkKensuke Tobitani

Kenji Katahira

Noriko Nagata

Research Center for Kansei Value Creation
Department of Human System Interaction, Graduate School of Science and Technology
Kwansei Gakuin University
Hyogo, Japan
lpark@kwansei.ac.jp
Abstract—To represent the texture of woven fabrics in computer graphics (CG), it is important to reveal the relation between
their physical properties and the texture caused by them. For
efﬁcient representation of a realistic texture, a new layered modelthat links visual impressions with physical properties is required.
Physical properties of woven fabrics include optical properties.
They are reproduced by bidirectional reﬂectance distributionfunction (BRDF) and the bidirectional transmittance distributionfunction (BTDF). However, it is not easy to handle BRDF andBTDF because of the enormity of these data. Therefore, it isnecessary to effectively integrate the dimensionality of BRDFand BTDF. In this paper, we propose the impression-evaluation
model to link visual impressions with physical properties of woven
fabrics. Moreover, to incorporate physical properties into themodel, we investigate the main physical factors of reﬂection andtransmission in woven fabrics using the multivariable analysis
technique of principal component analysis (PCA) of BRDF andBTDF. As a result, three principal components of BRDF andtwo principal components of BTDF are obtained. Therefore, it
becomes possible for inexpert people to make CG with realistic
texture of woven fabrics more intuitively and easily by incorporating physical factors into the impression-evaluation model.

I.

INTRODUCTION

Realistic representation of visual texture of material isrequired in many ﬁelds, including computer graphics (CG)and design. However, it is difﬁcult for inexpert people to set
parameters for making CG with realistic texture. Then, a structured model is required to express the relationship between
physical properties of material and visual impressions from it.
It becomes possible for inexpert people to make CG intuitively
and easily by using the model. In this study, we focus on
woven fabrics that are arranged in CG and consider the relationship of these physical properties and impressions. Opticalproperties that belong to physical properties of woven fabrics
are very important to represent the texture of woven fabrics.
The bidirectional reﬂectance distribution function (BRDF) andthe bidirectional transmittance distribution function (BTDF)
reproduce optical properties. In particular, these properties arenecessary to represent transparent fabrics such as lace curtain.
However, these measurements take a considerable time andeffort, and the amount of these data is enormous, so it isnecessary to integrate many complex data of optical properties.

Based on the above, this paper proposes the impressionevaluation model to link visual impressions with physicalproperties of woven fabrics. Moreover, we investigate the main
physical factors of reﬂection and transmission in woven fabrics
with transparency using the multivariable analysis technique ofprincipal component analysis (PCA) of BRDF and BTDF, andincorporate them into the impression-evaluation model.
Thus, it is realized to assume visual impressions fromphysical properties and identify physical properties from visual
impressions more intuitively and easily.
II.

RELATED WORKS

Some studies were conducted regarding the texture offabrics in CG. Uno et al. proposed a BTDF model to represent
realistic transparent fabrics[1]. Mizushima et al. recreated a3D model that takes into consideration woven structure[2].
Nomura et al. and Tobitani et al. proposed a woven cloth
microfacet BSDF model, the basis of the GGX[3][4]. Moreover, impressions of fabrics were researched. Impressions fromreal fabrics were compared with impressions from CG imagesof fabrics[5]. Impressions about softness were investigatedusing real fabrics[6], and impressions of fabrics color wereresearched under different lighting[7]. In addition, Tanaka et
al. acquired tactile impression data about 13 kinds of fabricusing the semantic differential method and composed material
texture dimension by factor analysis[8]. Tanno et al. evaluatedvisual and tactile texture impressions of 12 kinds of fabricusing 16 words and analyzed the result by PCA[9]. However,these studies have focused only on impressions of woven
fabrics texture, and they have not mentioned their physicalproperties.
Our previous research examined the relation between motion impressions of lace curtain and their dynamic properties
and suggested the possibility to estimate motion properties
from visual impressions[10]. However, optical properties havenot been assumed from visual texture impressions yet. On theother hand, Ferrero et al. interpreted many complex BRDF data
by PCA[11]. However, they analyzed the spectral BRDF of aglossy, colored ceramic, and they have not analyzed BRDF andBTDF of woven fabrics by PCA. Therefore, it is necessary
to extract their optical properties by PCA to associate theAuthorized licensed use limited to: Kwansei Gakuin University. Downloaded on September 10,2021 at 06:21:34 UTC from IEEE Xplore. Restrictions apply.

visual texture impression of woven fabrics with their opticalproperties.
III.

THE IMPRESSION - EVALUATION MODEL

This paper proposes the impression-evaluation model(Fig.1) that hierarchically represents the cognitive mechanismof affective evaluation for products and explains the relationship between a material’s physical properties that compose
products and affective evaluation.

Fig. 2.

close-up images of samples

Fig. 3.

S-OGM

When users evaluate a product, they don’t assume its speciﬁc physical properties, but they make a high order estimate,such as hierarchical impression, from physical properties andaffective evaluation. This high order estimate is not directly
made from physical properties. Actually, perceptual impressions primarily reﬂect physical properties, and recognitive
impressions are formed by integrating them. These impressions
are considered to become the standard affective evaluation
regardless of awareness of them.
The impression-evaluation model is composed of the following three factors:
1. Physical factors are speciﬁc material properties.
2. Impression factors are formed from physical factors.
3. Affective factors are recalled from impression factors.
In addition, impression factors include psychological processes from lower order to higher order. It is considered to beable to assume affective evaluation of a product or to conﬁgure
a product from affective evaluation by revealing the relationof each factor.

Fig. 1.

1) measurement conditions: In the coordinate system forthe measurement (Fig.4), the X-axis is the weft direction, theY-axis is the warp direction and the Z-axis is the normal vectorof the specimen plane. V is the viewpoint vector. L is the lightsource vector. N is the normal vector of the fabrics. H is thehalf vector of V and L. The number of measurement points is9216 points. Elevation angles of the camera θc take the values
from 10 degrees to 80 degrees per 10 degrees. Azimuth anglesof the camera φc take the values from 0 degrees to 330 degrees
per 30 degrees. Elevation angles of the light θL take the values
from 10 degrees to 80 degrees per 10 degrees. Azimuth anglesof the light φL take the values from 0 degrees to 330 degrees
per 30 degrees.

The impression-evaluation modelIV.

OPTICAL PROPERTIES OF WOVEN FABRICS

Optical properties are different for each woven fabric.
Therefore, we measured optical properties, such as reﬂectance,and transmission properties of woven fabrics to make highquality CG.

Fig. 4.

Coordinate system for the measurement

17 kinds of white polyester fabrics (plain fabrics) to be
used for making lace curtains were prepared (Fig.2).
B. measurement results
A. the measuring instrument
BRDF and BTDF ware measured with S-OGM (Spectrum- Optical Gyro Measuring) by rotating two axes of light andtwo axes of the sample (Fig.3).

An example of the measured BRDF is shown in Fig. 5,and the angle of incidence from the specimen plane is 10
degrees. Tendencies of reﬂection were greatly divided into two
in 17 kinds of woven fabric. The factor of the difference in theAuthorized licensed use limited to: Kwansei Gakuin University. Downloaded on September 10,2021 at 06:21:34 UTC from IEEE Xplore. Restrictions apply.

tendencies of reﬂection is considered to be an imitation linenﬁnish. An imitation linen ﬁnish is the processing method togive a hard texture such as linen to woven fabric. It is possiblethat 4 kinds of woven fabric (Fig. 5(b)) have been processedwith an imitation linen ﬁnish. Therefore, 13 kinds of woven
fabric (Fig. 5(a)) are analyzed using PCA in chapter 5.

(a)PC1(light φ : 0 degrees)(a)The tendency of reﬂection 1 (b)The tendency of reﬂection 2
Fig. 5.

(b)PC2(light φ : 0 degrees)Comparison of tendencies of BRDF (sample.1)

V.

PCA OF OPTICAL PROPERTIES

To integrate and interpret the enormous data of BRDF andBTDF, these data to be taken from 13 kinds of woven fabricselected at chapter 4 were analyzed using PCA.
A. BRDFThe main reﬂectance properties were obtained from PCAof 9216 BRDF data.
1) results and discussions: The distance from the origin of
the coordinate axes to points plotted represents the strengthof reﬂectance. Three principal components were extracted
from 9216 data of measured BRDF. Each contribution wasas follows: the ﬁrst principal component (PC1) is 68.6 %, thesecond principal component (PC2) is 15.1 % and the thirdprincipal component (PC3) is 7.3 %. Fig. 6 explains that aBRDF with high principal component loading was plotted foreach main component. PC1 is the BRDF’s diffuse component(Fig.6(a)) because reﬂected light diffuses in all directions. PC2
and PC3 are the BRDF’s specular component (Fig.6(b),(c))
because the incident light is reﬂected in the specular direction.
In PC3, components were extracted at 90 degrees, 120 degrees,
150 degrees, 210 degrees, 240 degrees and 270 degrees of φL .
More components of PC3 were extracted at a higher incident
angle of light than PC2. The difference of PC2 and PC3 isconsidered to relate to the woven structure.
B. BTDFThe main transmission properties were obtained from PCAof 9216 BTDF data.
1) results and discussions: Two principal components wereextracted from 9216 data of measured BTDF. Each contribution was as follows : the ﬁrst principal component (PC1)
is 58 %, and the second principal component (PC2) is 23.5%. Fig. 7 explains that a BTDF with high principal component loading was plotted for each main component. PC1 isthe BTDF’s diffuse component (Fig.7(a)) because transmitted(c)PC3(light φ : 90 degrees)Fig. 6.

PC’s of BRDF

light diffuses in all directions. PC2 is the BTDF’s speculartransmission component (Fig.7(b)) because the incident lightis transmitted in the specular transmission direction. Specular transmission components are divided into the directionaltransmission component, which goes through the thread, andthe direct transmission component, which goes through a space
between threads[3]. This time, φL is set for each 30 degrees.
Therefore, if φL becomes smaller, the difference of the directional transmission component and the direct transmission
component may appear.
VI.

C ONCLUSION

We have proposed the impression-evaluation model which
represents the relationship between physical properties ofmaterial and its impressions. In addition, measured BRDF
and BTDF data were analyzed using PCA. As a result, thediffuse component and the specular component were obtainedin BRDF, and the specular component was divided into twoby the incident angle. The diffuse transmission component andthe specular transmission component were obtained in BTDF.
In the future, we plan to experiment on visual impression
evaluation of woven fabrics, and to link it with optical properties obtained from PCA. Finally, it becomes possible to assume
optical properties from visual impressions without measuring
BRDF and BTDF. Therefore, it becomes easy to make realistic

Authorized licensed use limited to: Kwansei Gakuin University. Downloaded on September 10,2021 at 06:21:34 UTC from IEEE Xplore. Restrictions apply.

function of ceramic colour standards,Optics Express,Vol.19,Issue 20,pp.1919919211,2011)(a)PC1(light φ : 0 degrees)(b)PC2(light φ : 0 degrees)Fig. 7.

PC’s of BTDF

texture of woven fabrics in CG, and it will be possible towidely apply to the representation of other material’s texture.
R EFERENCES[1] H.Uno, Y.Mizushima, N.Nagata, and Y.Sakaguchi : Lace curtain : Measurementof BTDF and rendering woven cloth production of curtain catalog,ACM SIGGRAPH 2008,Talks,Measurement and Textures,Full conference DVD-ROM,0960abstract.pdf,Winner of 3rd place ACM Student Research Competition,2008[2] Y.Mizushima, S.Nomura, G.Umeizumi, N.Nagata, and Y.Sakaguchi : Lace curtain: Modeling and Rendering of Woven Structure using BRDF/BTDF - Productionof a catalog of curtain animations - ,ACM SIGGRAPH 2009,posters,modeling,Fullconference DVD-ROM,773-mizushima.pdf,2009[3] S.Nomura, A.Ishida, E.Ishigo, T.Okamoto, Y.mizushima, N.Nagata : Lacecurtain : Modeling and Rendering of Woven Cloth using Microfacet
BSDF -Production of a catalog of curtain animetions-,ACM SIGGRAPH
2011,posters,modeling,71,Selected as a Semi-ﬁnalist for ACM student ResearchCompetiton(SRC),2011[4] K.Tobitani, A.Ishida, S.Nomura, N.Nagata : Modeling and Rendering of Woven
Cloth Using Microfacet BSDF -Production of curtain catalog animetions-,The Japan
Society for Precision Engineering,Vol.79,No.11,2013[5] Hyun-Ju TAK, Yukio YAMASHITA, ”Subjective Evaluations of Appearance ofFabric Images Drawn by Computer Graphics and Inﬂuence of Rendering Parameters”. VISION Vol.23,No.1,19-33,2011[6] K.Morimoto, Choi Dong, Koo Kang. : Characteristics of KANSEI Words Used for
Subjective Evaluation of Textiles into Korean,SENI GAKKAISHI,Vol.63,3,pp.6366,2007[7] Hisa Takamori and Megumi Riki ”Fundamental Research about How the Color ofCloth Looks And What Impression It Gives in Different Illumination”,Kumamoto
University Faculy of Education,natural sciences,53,147-152,2004[8] Y.Tanaka, M.Tanaka and S.Chonan : Development of a Sensor System for Measuring Tactile Sensation; Proc.IEEE Sensors,554-557,2006[9] Masataka Tanno, Noriko Ito, and Mamijo Sakata : KANSEI Words Expressing
Fabrics Texture and Their Relationship with Visual and Haptic Senses ; Japanese
Cognitive Science Society,27,643-648,343-349,2010[10]

Ishida.A, Ishigo.E, Aiba.E and Nagata.N : Lace Curtain Rendering Animation ofWoven Cloth using BRDF/BTDF Estimating physical characteristic from subjective
impression,ACM SIGGRAPH 2012 : posters,Animation,6,p.5:50,2012[11]

A.Ferrero, J.Campos, A.M.Rabel, A.Pons, M.L.Hernanz, and A.Corrons : Principal components analysis on the spectral bidirectional reﬂectance distribution

Authorized licensed use limited to: Kwansei Gakuin University. Downloaded on September 10,2021 at 06:21:34 UTC from IEEE Xplore. Restrictions apply.