Shape from shading: analysis of implicit surfaces by synthesis

In this paper, we present a general framework for solving the shape from shading problem for a class of surfaces called implicit surfaces by applying image synthesis techniques from computer graphics. The method relies on iterative synthesis of images from object descriptions in order to minimize an error function. The technique is illustrated in detail for quadric surfaces, with the ellipsoid as the specific example. The advantage of this approach is that reconstructing the shape of objects from shading is possible even under very general imaging conditions.