Surface orientation from random texture with directional bias

A.P. Witkin (1981) described a method of shape-from-texture using tangent vectors of texture line segments by assuming directional isotropy of the vectors. However, the texture of natural scenes is often nonisotropic with detectable bias. The authors propose a maximum likelihood estimate for recovering surface orientation from surfaces with nonisotropic texture. A priori information of the bias is used to achieve the objective. Experiments using artificial and real data show that the method is far better than Witkin´s method for nonisotropic textures