Phase-Based Calibration Method for a Binocular Vision Sensor

In this paper, a phase based method to calibrate a binocular vision sensor is presented. In this method, only a surface plate is utilized. A series of phase shifting patterns are projected onto the surface plate. In this case, fundamental matrix can be calculated out from point correspondences on two image planes. As intrinsic parameters of each camera have been obtained according to related calibration method, essential matrix can be worked out. Then, rotation matrix and translation matrix with a coefficient are deduced based on singular value decomposition of the essential matrix. As size of the pattern can be confirmed from a look-up table, the coefficient is determined. So far, the binocular vision sensor is calibrated. In our proposed method, only one planar target without any pattern is necessary, which is with high precision and easy machined. As the calibration method is based on related phase algorithm, the calibration process is not affected by the ambient light which makes our calibration method robust. Experiment results show the precision of our proposed method. When we utilized a laser displacement sensor with a precision of 0.01 mm to determine size of the pattern, root mean square error of our calibration method is 0.103 mm with regard to the measurement area of about $100\times 80$ mm. Moreover, as planar features are widely existing, our proposed method is very suitable for on-site calibration and auto-calibration.