4 May 2012 The elimination of the errors in the calibration image of 3D measurement with structured light
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In the calibration process of structured light three-dimensional (3D) measurement system, the accuracy of the calibration points' image coordinates directly influences the system's measurement accuracy. Based on the analysis of errors in calibration points' image coordinates, mathematical models are built. A solution to eliminate errors in those image coordinates is proposed according to the further analysis of the models, and calibration points are designed to be circle for high-precision and steady extraction. The solution contains procedures as following: 1) A novel and real-time algorithm is proposed, which is used for the correction of the non-uniform intensity in image caused by non-uniform illumination and the camera's parameters. Taking preliminary extracted elliptical center coordinates and average gray value of the ellipses as known information, the intensity distribution of calibration images can be obtained by interpolation. Then the non-uniform intensity of calibration images is corrected in accordance with the interpolation results. 2) High frequency noise in the images is filtered. 3) At last, error of asymmetric perspective projection is also compensated based on its model. Simulation and experiment results indicate that this solution can efficiently reduce the calibration errors.
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Qi Xue, Zhao Wang, Junhui Huang, Jianmin Gao, "The elimination of the errors in the calibration image of 3D measurement with structured light", Proc. SPIE 8430, Optical Micro- and Nanometrology IV, 84300N (4 May 2012); doi: 10.1117/12.922150; https://doi.org/10.1117/12.922150

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