Multi Focus Structured Light for Recovering Scene Shape and Global Illumination

Illumination defocus and global illumination effects are major challenges for active illumination scene recovery algorithms. Illumination defocus limits the working volume of projector-camera systems and global illumination can induce large errors in shape estimates. In this paper, we develop an algorithm for scene recovery in the presence of both defocus and global light transport effects such as interreflections and sub-surface scattering. Our method extends the working volume by using structured light patterns at multiple projector focus settings. A careful characterization of projector blur allows us to decode even partially out-of-focus patterns. This enables our algorithm to recover scene shape and the direct and global illumination components over a large depth of field while still using a relatively small number of images (typically 25-30). We demonstrate the effectiveness of our approach by recovering high quality depth maps of scenes containing objects made of optically challenging materials such as wax, marble, soap, colored glass and translucent plastic.