Identifying the lights position in photometric stereo under unknown lighting

Reconstructing the 3D shape of an object from a set of images is a classical problem in Computer Vision. Photometric stereo is one of the possible approaches. It requires that the object is observed from a fixed point of view under different lighting conditions. The traditional approach requires that the position of the light sources is accurately known. In this paper, we explore photometric stereo under unknown lighting, showing that the lights position can be estimated directly from the data, when at least 6 images of the observed object are available.