Projector domain phase unwrapping in a structured light system with stereo cameras

Abstract

Phase-shifted sinusoids are commonly used as projection patterns in structured light systems consisting of projectors and cameras. They require few image captures per 3D reconstruction and have low decoding complexity. Recently, structured light systems with a projector and a pair of stereo cameras have been used in order to overcome the traditional phase discontinuity problem and allow for the reconstruction of scenes with multiple objects. In this paper, we propose a new approach to the phase unwrapping process in such systems. Rather than iterating through all pixels in the two cameras to determine the global phase of each pixel, we iterate through the projector pixels to solve for correspondences between the two camera views. An energy minimization framework is applied to these initial estimated correspondences to enforce smoothness and to fill in missing pixels. Unlike existing approaches, our method allows simultaneous unwrapping of both camera images and enforces consistency across them. We demonstrate the effectiveness of our approach experimentally on a few scenes.