鉴于棋盘格图案在摄像机标定中有着广泛的应用,因此为了对边缘模糊的棋盘格图像进行在线标定,针对目前棋盘格图像角点检测算法的局限性,提出了一种可以自动实现的棋盘格图像角点检测算法,该算法是利用周围图案对称和灰度值对比明显的独特性质,设计了由对称算子S和方差算子V组合而成的角点检测算子--对称方差算子（symmetry and variance）,简称SV算子.该算子不仅构思巧妙、易于实现、计算量小,而且对棋盘格图像的旋转变换和亮度变换具有鲁棒性和抗噪能力强的优点.实验结果表明,该算子对边缘模糊有良好的适应性,适用于摄像机的在线标定.

X-corner patterns are most widely used in camera calibration. In order to do online calibration for blurred image,we propose a new algorithm for X-corner detection based on the special character of X-corners: the pattern is symmetrical and the gray contrast greaty with each other In the algorithm the operator SV is designed to recognize X-corners which consists of symmetry operator S and variance operator V.The method is smart,easy to execute and robust to rotation,intensity change.It is also robust to image noise and edge blur where the intervention of man is not required.Experimental results show that the proposed algorithm can achieve excellent effects in X-corners detecting.in on line camera calibration.