Alex P. Pentland
Shape-from-shading and shape-from-texture methods have the serious drawback that they are applicable only to smooth surfaces, while real surfaces are often rough and crumpled. To extend such methods to real surfaces we must have a model that also applies to rough surfaces. The fractal surface model [Pentland 831 provides a formalism that is competent to describe such natural 3-D surfaces and, in addition, is able to predict human perceptual judgments of smoothness versus roughness - thus allowing the reliable application of shape estimation techniques that assume smoothness. This model of surface shape has been used to derive a technique for 3-D shape estimation that treats shading and texture in a unified manner.