表面反射特性と糸すじ模様を用いたテクスチャマッピング技法による織物質感表現

Abstract

In the computer graphic technology for indication of three-dimensional image of fabric surface, there is no indication method to express precisely the fabric textures by the surface reflection characters of fabric and thread pattern. It becomes possible to express the textures of four kinds of fabric with different materials using three kinds of surface reflection characters such as the luminance of surface reflection, distribution of irregular luminance, and thread pattern. We studied the extraction method of three characters and the procedure of generating textures from three characters and we considered the method of expressing the realistic fabric surface by computer graphics. The detection and expression of each character was performed according to the following procedures. (1) Luminance of surface reflection and distribution of irregular intensity were detected from nine images of fabric surface with various incidence angle γ. (2) The numerical model for reflection luminance was indicated by the function formula. Using least-squares method, this formula was obtained from the relation between the average gray level of image and cos γ. (3) Distribution of irregular luminance was indicated by the function formula. Using least-squares method, this formula was obtained from relation between the standard deviation value “σ” of gray level histogram of image and cos γ. (4) Extraction of thread pattern was carried out by detecting line segments on a fabric surface image. (5) The thread pattern was generated from the routine of “MONDRIAN-ART”. This routine was improved to adapt it to the result of measurements. (6) Finally, we used texture mapping technique to compose three kinds of characteristics on image, and generated the image that expresses textures.By using our technique for fashion design system and apparel CAD system, the expressing of a high precise fabric texture becomes possible.