一种大倾角敏捷成像卫星影像的直接定位方法

A direct positioning method of agile satellite with large-tilt-angle imaging

发展光学敏捷成像卫星的应用是国际上高分辨率对地观测领域的主要趋势,卫星在轨机动能力的增强使大倾角成像条件下的无控定位问题成为热点。为了获取影像对应的准确物方坐标,该文结合大倾角光学敏捷卫星的成像特点,对卫星俯视、侧视成像以及地面分辨率变化等系统误差源及其变化规律进行定量化推导分析,并在此基础上提出了适合短时间成像的轨道运动模型和参数估计方法,建立了顾及大倾角成像特点的严格几何定位模型,提供了影像无控制点直接定位的处理流程。实验结果证明所提出的方法能够较好地校正大倾角成像的几何偏差,使严密无控定位精度控制在1个像素内的水平。

The application of optical agile imaging satellite has become a major trend in the field of high-resolution land observation internationally.The increased on-orbit mobility of the satellite makes the hot spot of positioning without control points under the condition of large-tilt-angle imaging.In order to obtain the precise coordinates in the object space corresponding to the image,some imaging characteristics about the large-tilt-angle agile satellite were considered in this paper.The error sources and their regularities such as the overlooking and side-looking of the satellite and the variation of ground resolution were quantitatively deduced and analyzed.Then it presented an on-orbit motion equation and a parametric estimation method suitable for short-period imaging,built a rigorous geometric positioning model taking the characteristics of large-tilt-angle imaging into consideration and provided the procedures of image positioning without control points.Experimental results illustrated that the method could preferably calibrate the geometric offsets caused by large-tilt-angle imaging and control the precision of rigorous positioning without control points to less 1pixel.