Lasers structured light with phase-shifting for dense depth perception

Abstract

In this paper, a novel depth acquisition algorithm aiming to obtain high resolution of dense depth maps based on lasers is proposed. Which expands the projection range and improves the robustness. In addition, dithering projection and defocusing techniques are used by lasers with the improvement of the Diffraction Optical Elements (DOE) technology. Four patterns are projected onto the projects by the lasers and captured by camera, where three for three-step phase-shifting (TS-PS) patterns and the other one is for space stripe pattern. More important, the calibrated by the traditional methods are unavailable in the proposed devices. We propose an algorithm for obtaining intrinsic and extrinsic parameters of the system. A substantially different spatial stripe coding scheme is designed, which is utilized to assist in time coding (TS-PS) solving depth information. We proposed a novel phase unwrapping method to obtain accurate absolute phase map. In addition, to further boost the performance, we utilized Weighted Least Squares (WLS) strategy to optimize the detail of the depth map based on color image. Thereby high resolution, detail and dense depth map obtained. Compared with the current methods, the robustness of our method is improved which will be extended to more scenes. The quantitative and qualitative evaluation experiments demonstrate that the proposed algorithm consistently produces better quality dense and higher resolution depth maps, superior to the current depth sensor. Keywords: Dithering defocusing techniques, Phase-shifting, Space stripe, WLS