光学 精密工程, 2020, 28 (12): 2737, 网络出版: 2021-01-19
非公共视场双目相机位姿标定
C alibration of b inocular cam era w ith n on -com m on field of view
视觉测量 非公共视场 相机标定 直接线性变换 visual measurement non-common field of view camera calibration direct linear transformation method
摘要
针对现有双目位姿测量系统中仅有两个目标点, 无法利用额外标定物对两个无公共视场相机进行标定的问题, 提出一种无需改变系统结构, 可以直接利用现有设备的双目相机位姿标定方法。首先固定两相机坐标系与公共目标坐标系的位置关系, 通过多次移动标定物的方式得到多组坐标数据;然后, 利用一种基于直接线性变换方法的改进算法对每个相机坐标系到公共目标坐标系的转换关系进行优化求解;最后, 利用优化后的相机坐标系到公共目标坐标系的转换关系求得两个无公共视场相机坐标系之间的转换关系。利用两个相机坐标系之间的转换关系求得两目标点距离, 并作为标定精度的评价指标。实验结果表明: 当目标点处在各自相机视场范围内, 相机与目标点之间的测量距离为 700~1 300 mm时, 利用本文方法求得的目标点距离的均方差 <0. 2 mm, 满足实际应用需求。
Abstract
For the existing binocular position and attitude measurement system with only two target points, it is impossible to use additional calibration objects to calibrate the two cameras without a common field of view. In this study, a calibration method for a binocular camera without changing the system struc. ture and instead directly using the existing equipment was proposed. First, the relative position between the two camera coordinate systems and the common coordinate system was fixed, and multiple sets of co. ordinate data were acquired by moving the calibrator several times. An improved algorithm based on a di. rect linear transformation(DLT)method was used to optimize the relative transformation from each cam. era coordinate system to the common coordinate system. Finally, the relative conversion between the two camera coordinate systems was obtained using the optimized relative conversion from each camera coordi. nate system to the common coordinate system. The distance between the two target points could be ob. tained using the relative conversion between the two camera coordinate systems, and this distance was se. lected as the evaluation index of the calibration accuracy. The experimental results show that the mean square error of the distance between the target points obtained using this method is less than 0. 2 mm, which meets the practical application requirements.
李勤文, 倪首军, 王志乾, 李建荣, 沈铖武, 杨文昌, 刘玉生. 非公共视场双目相机位姿标定[J]. 光学 精密工程, 2020, 28(12): 2737. LI Qin-wen, NI Shou-jun, WANG Zhi-qian, LI Jian-rong, SHEN Cheng-wu, YANG Wen-chang, LIU Yu-sheng. C alibration of b inocular cam era w ith n on -com m on field of view[J]. Optics and Precision Engineering, 2020, 28(12): 2737.