基于相对点矩的SAR图像匹配算法

　　为了解决景象匹配导航系统中图像存在旋转误差以及遮挡问题，提出了一种基于相对点矩的SAR图像匹配算法。Harris角点提取算子结合亚像素精确定位算法可以获得高精度的特征点坐标，而Hu不变矩具有平移、旋转、缩放(RTS)不变性，结合两者优点，本文首次提出了相对点矩的概念。相对点矩同样具有RTS不变性，可以实现任意旋转角度下的图像匹配，通过选择合适的特征半径，可以抵抗一定程度的遮挡。针对粗匹配点中存在的误差匹配点，采用相似三角形原理筛选并摒弃;最后，通过最小二乘法给出最优估计值。实验结果表明，该算法满足高精度、实时性和一定的抗干扰要求。

　　Abstract:

　　To solve the problem that there exits rotation error and shading in the images of the scene matching aided navigation system， a new matching algorithm for SAR image based on relative point moment invariants is proposed. Feature point coordinates of high precision can be achieved by the Harris corner point operator and the sub-pixel positioning algorithm .When Hu moment invariants with their properties of translation， rotation and scaling(RTS) invariability are combined with high precision feature points， we proposed the concept of relative point moment invariants for the first time. The relative point moment invariants also have the RTS invariability properties，therefore image matching of arbitrary rotation angle can be achieved by using the relative point moment invariants. Moreover， this matching algorithm can resist certain degree of shading. Match points witch error are excluded according to the principle of similar triangles. Finally， the optimal estimation is given by the least square method. Experimental results show that， this algorithm satisfies the high-precision， real-time and certain degree of anti-interference requirements.