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为了修正时间延迟积分(TDI)CCD空间相机像移补偿计算中的地心距误差,减小其对像移速度相对误差的影响,推导出了星下点成像的像移速度计算模型。通过该模型分析了地心距误差对像移速度相对误差的影响。根据地心距误差的来源,分两步修正了地心距误差:采用WGS-84(World Geodetic System)模型修正地球的偏心率引起的地心距误差;采用地球海拔高度数据源(USGS DEM)制作电子高程图,修正了地球表面海拔高度不同引起的地心距误差。推导出了地心距误差修正后的空间相机星下点成像的像移速度模型。修正后模型计算以及分析结果表明:WGS-84模型和电子高程图对地心距误差的修正消除像移速度相对误差最大分别为2.85%和1.76%。地心距误差的修正极大地减小了前向(沿TDI CCD积分方向的)匹配误差,提高了TDI CCD空间相机成像质量。
In order to correct the geocenter distance error in the TDI CCD space camera image compensation compensation and reduce its influence on the relative error of the image shift speed, the imaging velocity model of the satellite under point imaging is deduced. Through the model, the influence of the error of the geocentric distance on the relative error of the moving speed of the image is analyzed. Based on the origin of the geo-centering error, the geo-centering error was corrected in two steps: the geodetic error due to the Earth’s eccentricity using the WGS-84 (World Geodetic System) model; and the geodetic data from the Earth’s Altitude Data Source (USGS DEM) Electronic elevation map, amending the earth’s surface elevation error caused by the difference between the center. The model of imaging velocity is deduced from the satellite imaging of the space camera after the correction of the geocentric distance and error. The corrected model calculation and analysis results show that the relative errors of the WGS-84 model and the electronic elevation map for the correction of the earth center distance error are 2.85% and 1.76% respectively. The correction of the geocentric distance error greatly reduces the matching error in the forward direction (along the TDI CCD integral direction) and improves the imaging quality of the TDI CCD space camera.