A scalable framework for image-based material representations
Tobias Franke, Dieter W. Fellner · 2012
Complex material-light interaction is modeled mathematically in its most basic form through the 4D BRDF or the 6D spatially varying BRDF. To alleviate the overhead of calculating correct shading with a complex BRDF consisting of many parameters, many methods resort to textures as containers for BRDF information. The most common among them is the Bidirectional Texture Function, where a set of base textures of the material under different illumination and viewing conditions is stored and used as a lookup table at runtime. A wide variety of compression algorithms have been proposed, which usually differ only in some basis notation. Also, several other schemes aside from the BTF exist that make use of multiple textures as containers for surface appearance data, which either compress the surface transfer function or the response in change of luminance with a suitable basis function.