0448393 20240111140908.320151022235959.9 84955570948 000390305600004 10.1145/2804408.2804419 8 s. E cav_un_epca*0448392978-1-4503-3812-725-32New YorkACM2016 BRDF anisotropic shape illumination measure cav_un_auth*0101086 Department of Pattern Recognition 100 Filip Jiří UTIA-B Rozpoznávání obrazu Department of Pattern Recognition RO RO Ústav teorie informace a automatizace AV ČR, v. v. i. http://library.utia.cas.cz/separaty/2015/RO/filip-0448393.pdf 4.3MB cav_un_auth*0303439 GA14-10911S GA ČR CZ cav_un_auth*0303412 GA14-02652S GA ČR CZ The majority of the materials we encounter in the real-world have variable reflectance when rotated along a surface normal. This view and illumination azimuthally-variable behavior is known as visual anisotropy. Such behavior can be represented by a four-dimensional anisotropic BRDF that characterizes the anisotropic appearance of homogeneous materials. Unfortunately, most past research has been devoted to simplistic three dimensional isotropic BRDFs. In this paper, we analyze and categorize basic types of BRDF anisotropy, use a psychophysical study to assess at which conditions can isotropic appearance be used without loss of details in material appearance. To this end, we tested the human impression of material anisotropy on various shapes and under two illuminations. We conclude that subjects sensitivity to anisotropy declines with increasing complexity of 3D geometry and increasing uniformity of illumination environment. Finally, we derive and perceptually validate a computationally efficient measure of material visual anisotropy. cav_un_auth*0320519 ACM SIGGRAPH Symposium on Applied Perception 13.09.2015-14.09.2015 Tubingen DE BD 2016 1 PR RVO:67985556 http://hdl.handle.net/11104/0250570 S 3+4 Proceedings Paper Computer Science Artificial Intelligence 2016 84955570948 SCOPUS 000390305600004 WOS 4.3MB cav_un_epca*0448392 Proceedings of the ACM SIGGRAPH Symposium on Applied Perception 978-1-4503-3812-7 25 32 New York ACM 2016