Binocular stereo vision system based on phase matching

Binocular stereo vision is an efficient way for three dimensional (3D) profile measurement and has broad applications. Image acquisition, camera calibration, stereo matching, and 3D reconstruction are four main steps. Among them, stereo matching is the most important step that has a significant impact on the final result. In this paper, a new stereo matching technique is proposed to combine the absolute fringe order and the unwrapped phase of every pixel. Different from traditional phase matching method, sinusoidal fringe in two perpendicular directions are projected. It can be realized through the following three steps. Firstly, colored sinusoidal fringe in both horizontal (red fringe) and vertical (blue fringe) are projected on the object to be measured, and captured by two cameras synchronously. The absolute fringe order and the unwrapped phase of each pixel along the two directions are calculated based on the optimum three-fringe numbers selection method. Then, based on the absolute fringe order of the left and right phase maps, stereo matching method is presented. In this process, the same absolute fringe orders in both horizontal and vertical directions are searched to find the corresponding point. Based on this technique, as many as possible pairs of homologous points between two cameras are found to improve the precision of the measurement result. Finally, a 3D measuring system is set up and the 3D reconstruction results are shown. The experimental results show that the proposed method can meet the requirements of high precision for industrial measurements.