Correlation model for 3D texture

While an exact definition of texture is somewhat elusive, texture can be qualitatively described as a distribution of color, albedo or local normal on a surface. In the literature, the word texture is often used to describe a color or albedo variation on a smooth surface. We refer to such texture as 2D texture. In real world scenes, texture is often due to surface height variations and can be termed 3D texture. Because of local foreshortening and masking, oblique views of 3D texture are not simple transformations of the frontal view. Consequently, texture representations such as the correlation function or power spectrum are also affected by local foreshortening and masking. This work presents a correlation model for a particular class of 3D textures. The model characterizes the spatial relationship among neighboring pixels in an image of 3D texture and the change of this spatial relationship with viewing direction