复杂地形区SAR图像无地面控制点精确对地定位技术研究

SAR image geo-location is the important procedure of applications with SAR remote sensing data. SAR image geo-location in complex terrain regions and overseas faces the difficulties that, (1) the terrain fluctuation should not be neglected, (2) the earth model equation cann’t accurately describe the actual terrain, (3) ground control points (GCPs) are unavailable, which lead to the poor geo-location accuracy. In order to improve the geo-location accuracy of SAR image in those regions, technologies of SAR image accurate geo-location without GCPs were studied in this project, and the work train is “GCPs extraction → the orientation parameters calibration → the ground coordinates calculation”. GCPs were automatic extracted from SAR image based on SAR image simulation, matching of the simulated SAR image and the actual SAR image, and so on. It’s a breakthrough for the limitation of artificial field measurements in order to acquire GCPs; Accurate orientation parameters calibration was realized by comprehensive using generalized ridge estimation (GRE) and least square (LS) estimation. This work overcomes the difficulty of ill-conditioned system of normal equation caused by the strong correlation of orientation parameters; By designing reasonable iteration strategy and selecting the initial point’s coordinate, ground coordinates of SAR image were calculated based on DEM. The study in this project will solve the difficulty of SAR image accurate geo-location without GCPs, and effectively raise the geo-location accuracy of SAR image in complex terrain regions and overseas. The project has important theoretical significance and practical application value.

SAR图像对地定位是SAR遥感数据应用的重要环节，而地形复杂地区和境外地区的SAR图像对地定位，面临地形起伏不可忽略、地球模型方程难以准确描述实际地形、地面控制点获取困难等问题，定位精度较差。为了提高上述地区SAR图像对地定位精度，本项目拟研究复杂地形区无地面控制点的SAR图像高精度对地定位技术，按照“控制点提取→定向参数标定→地面坐标解算”思路展开。通过SAR图像仿真、仿真图像与实际图像匹配等技术环节，实现控制点自动提取，突破对人工实地布设控制点的依赖；综合采用广义岭估计、最小二乘估计等方法，克服参数强相关导致的法方程病态问题，实现定向参数高精度标定；通过设计合理的迭代策略、初始点坐标给定策略，实现DEM支持的SAR图像精确定位坐标解算。本项目的研究将解决无地面控制点的SAR图像精确对地定位难题。研究成果对于提高地形复杂地区和境外地区SAR图像对地定位精度具有重要理论意义和实际应用价值。

SAR图像对地定位是SAR遥感数据应用的重要环节，而地形复杂地区和境外地区的SAR图像对地定位，面临地形起伏不可忽略、地球模型方程难以准确描述实际地形、地面控制点获取困难等问题，定位精度较差。为了提高上述地区SAR图像对地定位精度，本项目开展了复杂地形区无地面控制点的SAR图像高精度对地定位技术研究，通过SAR图像仿真、仿真图像与实际图像匹配等技术环节，实现了控制点自动提取，突破了对人工实地布设控制点的依赖；设计并实现了基于广义岭估计的定向参数高精度标定算法，克服了参数强相关导致的法方程病态问题；通过设计合理的迭代策略、初始点坐标给定策略，实现了DEM支持的SAR图像精确定位坐标解算。实验结果表明，当采用格网间距90米、绝对水平精度20米、绝对高程精度16米、置信度90%的SRTM DEM作为支撑条件时，对于起伏较大的山区，SAR图像无控制斜侧视定位的高程误差一般在数十米以内，平面坐标误差与SRTM DEM内插后格网间距量级相当，显著提高了SAR图像无控制定位精度。研究成果对于完善SAR图像定位理论体系、提高地形复杂地区和境外地区对地定位精度具有重要理论意义和实际应用价值。