Reeectance and Texture of Real-world Surfaces Reeectance and Texture of Real World Surfaces

In this work, we investigate the visual appearance of real-world surfaces and the dependence of appearance on scale, viewing direction and illumination direction. At ne scale, surface variations cause local intensity variation or image texture. The appearance of this texture depends on both illumination and viewing direction and can be characterized by the BTF (bidirectional texture function). At suuciently coarse scale, local image texture is not resolvable and local image intensity is uniform. The dependence of this image intensity on illumination and viewing direction is described by the BRDF (bidirectional reeectance distribution function). We s i m ultaneously measure the BTF and BRDF of over 60 diierent rough surfaces, each observed with over 200 diierent c o m binations of viewing and illumination direction. The resulting BTF database is comprised of over 12,000 image textures. To enable convenient use of the BRDF measurements, we t the measurements to two recent models and obtain a BRDF parameter database. These parameters can beused directly in image analysis and synthesis of a wide variety of surfaces. The BTF, BRDF, and BRDF parameter databases have important implications for computer vision and computer graphics and and each i s made publicly available.