Analysis of BRDF/BTDF for the texture representation of woven fabrics based on the impression-evaluation model

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 model that links visual impressions with physical properties is required. Physical properties of woven fabrics include optical properties. They are reproduced by bidirectional reflectance distribution function (BRDF) and the bidirectional transmittance distribution function (BTDF). However, it is not easy to handle BRDF and BTDF because of the enormity of these data. Therefore, it is necessary to effectively integrate the dimensionality of BRDF and 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 the model, we investigate the main physical factors of reflection and transmission in woven fabrics using the multivariable analysis technique of principal component analysis (PCA) of BRDF and BTDF. As a result, three principal components of BRDF and two 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.