中文摘要：

针对移动式三维视觉测量系统所采用的圆形标记点成像亮度较低且不均匀等问题，提出了一种基于灰度差重心法的识别与提取算法。获取标记点近似成像中心及成像区域。在成像区域内沿四个方向扫描得到像素级边缘点；利用灰度差重心法进行亚像素定位；对亚像素级边缘点进行椭圆拟合，得到标记点成像中心位置。实验结果表明，像素级边缘检测算法运行时间为3ms左右；亚像素定位算法椭圆拟合最大偏差小于o．08pixel，平均偏差小于0．03pixel。与其他提取算法相比，该算法在速度及定位精度方面有一定的提高，更适用于移动式三维测量用圆形标记点的提取。

英文摘要：

Circular targets used for mobile three-dimensional （3D） vision measurement system have apparent disadvantages such as low and uneven imaging brightness. An approach based on gray difference weighted centroid algorithm is proposed for the targets＇ recognition and extraction. Approximate imaging centers and imaging areas of the circular targets are acquired, and then the pixel edge points are detected by scanning the imaging areas in four directions. Sub-pixel edge is located by using gray difference weighted centroid algorithm. And sub-pixel edge points are fitted with ellipse and thus the imaging center positions of the circular targets are acquired. Experimental results indicate that with the proposed algorithm, the elapsed time is about 3 ms, the maximum error of ellipse fitting is less than 0.08 pixel and the average error is less than 0.03 pixel. Compared with other traditional extraction algorithms, it makes great improvement in speed and localization precision, and is more appropriate for the extraction of circular targets used for mobile 3D vision measurement system.