提出一种利用标志点构建全局测量控制点的视觉测量三维数据拼接方法.在被测自由曲面上粘贴标志点,并在被测区域放置基线尺,采用1台数码相机在不同视点拍摄标记点和基线尺图像,由此求解数码相机在不同视点的坐标系变换关系.在此基础上,根据立体视觉模型确定标志点三维坐标,转换到全局坐标系下,形成全局测量控制点.视觉传感器在不同位置对各局部区域进行三维扫描,获得局部区域内标志点在局部测量坐标系下的坐标,通过至少3个非共线标志点解算局部坐标系到全局坐标系的变换,从而将实现局部三维数据的拼接.该方法操作简便,适合现场使用.实验结果表明,x,y,z坐标的拼接误差分别为0.03mm,0.02mm,0.07mm.
A 3 D data registration method was proposed for vision measurement using mark points as global measurement control points. Mark points were attached to the measured objects and one or more baseline rulers were put in the measured area. The images of mark points and the baseline rulers were captured by a digital camera from different viewpoints, by which the coordinate frame transformations between viewpoints were estimated. Using the stereo vision model, the local coordinates of the mark points were determined, and then converted at the global coordinate frame, forming the global measurement control points. Scanning different parts of the object at different positions, the vision sensor obtained the coordinates of some mark points in the local coordinate frame of the sensor. The transformation from the local to the global coordinate frame was com- puted using at least three non-collinear mark points, thus the 3D data acquired by the sensor at different positions were integrated into the global coordinate frame. The proposed method is convenient and applicable in field measurements. Experimental results show that the registration error in x, y, z axis are 0. 03 mm, 0.02 mm, 0.07 mm respectively.