Stereo Vision-based Calibration Approach for Position Parameters of LED in Photometric Stereo

Focusing on the problems of complex operation and large error of the light source position calibration method based on specular reflection in photometric stereo vision, this paper proposes a method of light-emitting diode ( LED) light source position parameter calibration based on stereo vision. In photometric stereo, the LED light source is photographed using binocular stereo vision system, and the three-dimensional coordinates of the light source are calculated using the least square method based on the stereo vision imaging matrix. Simultaneously, the structural parameters of the light source position calibration system are obtained through the rotation and translation relationships between the cameras in the photometric stereo and binocular stereo vision systems, and the spatial position relationship of the LED light source, which is relative to the camera in the photometric stereo system, is obtained. The experimental result shows that the proposed method can effectively solve the problem of the cumbersome operation of the specular reflection calibration method, and when compared to the method based on specular reflection, the proposed method can obtain more accurate LED light source position calibration parameters using the easy-to-operate stereo vision system. The mean absolute error (MAE) and root mean square error (RMSE) of the light source diagonal distance obtained by the proposed method are lower than those obtained by the specular reflection method.