Joint calibration of a full-field autonomous ranging system and camera exterior orientation parameters

This paper addresses the challenge of fusing image and ranging data for high-precision in-orbit measurement of large antennas by proposing a calibration method for the exterior orientation parameters between a camera and a full-field autonomous ranging system. The ranging system integrates a laser rangefinder (LRF) with a two-axis turntable and employs full-field autonomous point-by-point measurement to enable large-scale, high-accuracy distance measurement. A monocular camera provides essential line-of-sight vectors to target points for system calibration and 3D reconstruction. First, a calibration model based on 13 exterior orientation parameters is established to describe the spatial relationships among the three motion axes of the two-axis turntable and the LRF. These axes exhibit a non-orthogonal and non-intersecting configuration in the camera coordinate system. Second, a bundle adjustment algorithm is developed for the joint multi-station calibration of the system's exterior orientation parameters. Furthermore, a vision-guided autonomous aiming and ranging algorithm is developed using prior information, achieving precise laser beam aiming at the target center. Experimental results demonstrate root mean square errors (RMSEs) of 0.010° in yaw and 0.012° in pitch for the vision-guided aiming method. In the joint calibration of the camera, two-axis turntable, and LRF, the reprojection error on the image plane achieves an RMSE of 1/5 pixel. The proposed method effectively calibrates the spatial geometry of the three non-orthogonal motion axes, enabling the calibrated measurement system to attain sub-millimeter accuracy.