Comment on “Numerical shape from shading and occluding boundaries”

The paper “Numerical shape from shading and occluding boundaries” [101 proposed a method to determine the 3D shape of an object from a single brightness image using the smoothness constraint on surface orientations, and the orientations of the surface given along ari occluding boundary. This paper contributed both a specific algorithm for solving a specific problem, and a general approach that could be applied in other low-level vision problems