Overcoming Shadows in 3-Source Photometric Stereo

—Light occlusions are one of the most significant difficulties of photometric stereo methods. When three or more images are available without occlusion, the local surface orientation is overdetermined so shape can be computed and the shadowed pixels can be discarded. In this paper we look at the challenging case when only two images are available without occlusion, leading to a 1 degree of freedom ambiguity per pixel in the local orientation. We show that, in the presence of noise, integrability alone cannot resolve this ambiguity and reconstruct the geometry in the shadowed regions. As the problem is ill-posed in the presence of noise, we describe two regularization schemes that improve the numerical performance of the algorithm while preserving the data. Finally the paper describes how this theory applies in the framework of color photometric stereo where one is restricted to only three images and light occlusions are common. Experiments on synthetic and real image sequences are ...

• Type: Journal
• Year: 2011
• Where: PAMI
• Authors: Carlos Hernández, George Vogiatzis, Roberto Cipolla
• Keywords: Image, Operations Research, PAMI 2011, Photometric Stereo, Photometric Stereo Methods