Sources from shading

The authors assume a Lambertian shading model with unknown light source directions. It is shown that information on the occluding boundary puts strong constraints on the light source directions. For a small number of light sources, from sufficiently different directions, additional information from intensity extrema will be sufficient to determine the source directions. If there are two, or three, views of the object then the light sources can be determined without extrema information. The authors report experiments performed on synthesized images.<<ETX>>