星载SAR影像地理编码算法研究

对SAR成像机理进行了研究,据此对SAR的成像几何进行了精确构建。所建距离向和方位向成像方程的参数可以由卫星轨道参数和其它成像参数直接获得。若轨道参数精度较高,这些参数就可以直接用于SAR影像的地理编码,生成SAR正射影像。为提高校正精度,研究了以这些参数为初值利用少量控制点对成像方程参数进行非线性求解的算法,并利用该算法完成了ERS2SAR影像的地理编码过程。利用该算法产生的正射影像和地形图的配准精度在东西和南北向都小于50m,可与其它基于地形图坐标系统的图像匹配使用。

Study on the Geocoding Algorithm of Space-borne SAR Image

Based on the study of SAR imaging mechanism, the SAR imaging geometry is reestablished by the range equation in the range direction and the SAR Doppler equation in the azimuth direction. The parameters of these equations can be derived through the SAR track parameters and the other SAR imagery parameters and used directly for the geocoding. In order to improve the geocoding accuracy, and algorithm is developed to refine the parameters of SAR imaging equations using some collected tiepoints and local DEM. The weighted least square method is adapted to solve these nonlinear equations. The application of this geocoding algorithm to ERS 2 SAR data are carried out, and the resulted geometry correction accuracy is less then 50 meters in both North South and East West directions.