基于高精度景象匹配的SAR平台定位方法

提出一种利用SAR图像与光学基准图高精度匹配实现SAR平台定位的方法。利用成像中间时刻SAR平台与SAR图像中心线上物点在水平面的投影共线的特性，在图像中心线上均匀选取若干点作为匹配点，并与光学基准图进行高精度景象匹配获取它们的物点坐标；根据这些物点坐标估计出图像中心线在当地水平面投影的直线方程；利用直线信息和斜距高度信息计算SAR平台在水平面上的投影点位置，进而计算得到成像中间时刻SAR平台的空间位置。为了进一步提高匹配精度，分别提出对正侧视和斜视SAR图像匹配区域进行几何粗校正的方法。还分析了不同误差因素对平台定位精度的影响，并给出精度估计公式。仿真和实际图像实验结果表明，方法正确可行，具有较高的定位精度，具备工程实用价值。
A SAR platform location method which utilizes the high-precision scene matching of SAR images and optical reference images was proposed. According to that the projections of SAR platform and object point in SAR image centerline are collinear, some points on the centerline were equably engaged as control points in the proposal method, and then the spatial position was obtained by matching with optical reference image. The equation of the projection line on the local horizon of centerline was estimated with the points. The projection point position of the SAR platform on the horizontal plane was calculated by making use of the straight line and slant-range-altitude information, as well as the spatial position of the platform. Considering the difference between boresight and squint imaging mode, rough rectifying methods were respectively proposed according to the two modes to improve the matching precision. The impact of different errors on location precision was also analyzed and the precision estimation formulas were derived. Both simulation and real data test results show high accuracy and precision of the proposed method, thus bringing forth good practical value for engineering.