A global algorithm for shape from shading

A global algorithm for reconstructing shape from shading is described. This algorithm incorporates an earlier local algorithm that has been shown to be capable of fast, robust surface reconstruction for general surfaces if a small amount of information on the surface is provided. The new algorithm is capable of determining this information automatically, and thus can reconstruct a general surface from shading with no a priori information on the surface. In experimental tests on complex synthetic images, this algorithm has produced good surface reconstructions over most of the image. For 128 × 128 images, the reconstruction took less than 30 s on a DECstation 5000. The algorithm appears noise resistant, giving good reconstructions even with an added pixel noise of ±10%