Smith, G. B. (1983). The relationship between image irradiance and surface orientation. SRI INTERNATIONAL MENLO PARK CA ARTIFICIAL INTELLIGENCE CENTER.
A formulation of shape from shading is presented in which surface orientation is related to image irradiance without requiring detailed knowledge of either the scene illumination or the albedo of the surface material. The case for uniformly diffuse reflection and perspective projection is discussed in detail. Experiments aimed at using the formulation to recover surface orientation are presented and the difficulty of nonlocal computation discussed. We present an algorithm for reconstructing the 3-D surface shape once surface orientations are known.