Calibration based on ray-tracing for multi-line structured light projection system

Multi-line Structured Light Projection System (MSLPS) is widely used with the advantages of high-contrast stripes and high robustness in high-speed dynamic reconstruction in comparison with Phase Modulation System (PMS). However, existing calibration methods are either sophisticated or low-accuracy in large visual field application because the bending of line structured light plane caused by lens distortion is inevitable and projector calibration is necessary. Therefore, in this paper, we present an accurate and robust calibration method based on ray-tracing, which establishes accurate relationship between subpixel coordinates of each bending line structured light plane and 3D coordinates based on camera coordinate system without projector calibration. As long as placing a checkerboard at random positions, MSLPS can be calibrated and hence is more suitable in practical application. Experimental results demonstrated that, compared with existing line structured light strategies, the proposed method could achieve more accurate and robust 3D reconstruction and the calibration process is simpler and easier to implement.