A theory of photometric stereo for a general class of reflectance maps

The authors present the main results of a theory of photometric stereo for non-Lambertian surfaces. First, they propose a class of reflectance maps that can be used for a realistic representation of real-world reflection. Second, they ask how many light sources are needed for inverting this class of reflectance maps. It is shown that three light sources are sufficient for a globally unique inversion for the entire class of reflectance maps. Finally, the authors address the issue of completeness of reconstruction. They show that if k lights are sufficient for a globally unique inversion, 2k lights are necessary for a complete inversion