大视场多像机视频测量系统的全局标定

针对大视场多像机视频测量系统的全局标定,提出并实现了一种基于近景摄影测量技术的高精度像机标定方法.首先,设计一种带有标志点的十字架形标定参考物,十字架正反两个表面粘贴有环形的编码标志点和圆形的非编码标志点.然后,在现场用工业摄影测量系统XJTUDP重建出双面标定十字架的精确结构尺寸数据；将标定十字架在公共视场范围内依次摆出多个姿态,并控制多像机同步拍摄各姿态的图像.最后,为大视场像机选择10参数非线性成像模型,对采集的图像组依次进行标定运算,标定出各像机的内参数和畸变参数,并全局定向出各个像机在统一坐标系下的外方位参数.实验结果表明,该标定方法的重投影误差小于0.05 pixel;利用标定结果测量高精度标准尺长度,相对误差小于1/4 000,可满足大视场多像机视频测量对精度和效率的要求.

Global calibration for muti-camera videogrammetric system with large-scale field-of-view

An accurate global calibration method for a muti-camera videogrammetric system with large field-of-view is presented.Firstly,a cross target with feature points pasted on its two sides is designed as the calibration reference pattern,and the world coordinates of these feature points are reconstructed using the XJTUDP photogrammetric system.Then,the calibration target is placed in the public field-of-view and its images shown at different orientations are captured by the four cameras simultaneously.Finally,based on a 10-parameter nonlinear camera model,the capatured images are calibrated successively and the camera interior parameters and global orientation parameters with respect to a predefined global coordinate system are obtained.Experimental result indicates that the proposed calibration method can offer a considerable accuracy in a re-projection error less than 0.05pixel.By the proposed method,the four-camera videogrammetric system can achieve a relative accuracy of 1 / 4 000on length measurement.It can satisfy the demands of the multi-camera videogrammetric measurement with large field-of-view for precision and efficiency.