ABSTRACT
The shading models presented in Chapter 10 assume that a diffuse surface has uniform reflectance cr. This is fine for surfaces such as blank paper or painted walls, but it is inefficient for objects such as a printed sheet of paper. Such objects have an appearance whose complexity arises from variation in reflectance properties. While we could use such small triangles that the variation is captured by varying the reflectance properties of the triangles, this would be inefficient.
