Multipath mitigation in Time of Flight 3D sensor based on direct and global seperation technique

Abstract

3D Time-of-Flight sensing technology provides distant measurements from the camera to the scene in the field of view, for complete depth map of a scene. It works by illuminating the scene with a modulated light sources and measuring the phase change between illuminated and reflected light. This is translated to distance, for each pixel simultaneously. The sensor receives the radiance which is combination of light received along multiple paths due to global illumination. This global radiance causes multi-path interference. Separating these components to recover scene depths is challenging for corner shaped and coronel shaped scene as number of multiple path increases. It is observed that for different scenes, global radiance disappears with increase in frequencies beyond some threshold level. This observation is used to develop a novel technique to recover unambiguous depth map of a scene. It requires minimum two frequencies and 3 to 4 measurements which gives minimum computations.