Analyzing the bidirectional texture function

The observed image texture for a rough surface has a complex dependence on the illumination and viewing angles due to effects such as local shading, interreflections, and the shadowing and occlusion of surface elements. We introduce the dimensionality surface as a representation for the visual complexity of a material sample. The dimensionality surface defines the number of basis features that are required to represent the space of observed textures for a surface as a function of ranges of illumination and viewing angles. Basis textures are represented using multiband correlation functions. We study properties of the dimensionality surface for real materials using the Columbia Utrecht Reflectance and Texture (CUReT) database. The analysis shows that the dependence of the dimensionality surface on ranges of illumination and viewing angles is approximately linear with a slope dependent on the complexity of the sample