基于SPOT 5辅助数据的有理函数模型建立及系统误差改正

Building of RPC Model Based on SPOT5 Appendix Data and Correction of Systematic Errors

首先利用SPOT5卫星的辅助数据如卫星的瞬时位置、姿态及CCD的观测方向等计算地面坐标系中一定间隔的CCD像元的观测方向,通过求观测方向与地球椭球面的交点建立一定密度的地面虚拟控制点格网。然后以这些虚拟控制点为基础数据,用最小二乘法解算表示虚拟控制点物方与像方坐标对应关系的有理函数模型,进行基于有理函数模型的立体影像同名像点的前方交会。与实际量测地面点坐标进行对比,发现有明显的定位系统误差。根据系统误差分布特点提出了在像方和物方进行系统误差改正的简单实用的方案,用SPOT5的HRG和HRS数据做了相关实验,证明通过在物方或像方改正系统误差,可以达到较高的定位精度。

This paper computes look direction in terrestrial coordinate system of CCDs with certain gap using auxiliary data of SPOT5 such as instantaneous position,attitude and CCD look direction of satellite, constructing grid of virtual grourid control points by computing intersection point of look direction and the earth ellipsoid surface. And then, resolves RPC which indicates virtual control points＇ coordinate corresponding relationship in image space and ground space with least square using these virtual control points. Carries out forward intersection of stereo images＇ tie-points based on RPC to compute the coordinates of ground points and compares them with field measured ones and finding out that there are obvious positioning systematic errors. The paper brings forward a simple and useful scheme, which corrects the systematic errors in image and ground space according to their characteristics. Tests with HRG and HRS data of SPOT5 verified, that it can gain a higher positioning accuracy by correcting systematic errors in image and ground space.