星载线阵遥感器在轨几何外检校技术研究

Research of Geometric Exterior Calibration of Space-borne Linear Array Sensor

文章叙述了星载线阵遥感器的严格成像几何模型,分析了姿态角误差随时间的变化情况,发现俯仰角误差和滚动角误差随时间变化的线性规律。在此基础上,提出一种基于姿态角常差检校模型同时顾及姿态角误差随时间变化的线性量的在轨几何外检校方法,检校参数不仅由三个角元素误差组成,同时包含俯仰角误差和滚动角误差随时间变化的线性量,并给出了相应参数求解方法。利用高精度控制数据和高分辨率卫星影像验证了文章的模型和算法。试验结果表明,改进后的外检校试验结果优于常差检校模型,尤其是在线阵方向上的定位精度从17.9个像素提高到1.0个像素,这说明了俯仰角误差随时间变化的线性量影响很大;在沿轨方向的定位精度从5.3个像素提高到3.7个像素,说明滚动角上的随时间变化的线性量客观存在,但是相对于俯仰角误差随时间变化的线性量影响不大。采用文章提出的在轨几何外检校方法,影像定位精度显著提升。

This paper briefly describes imaging geometric model of space-borne linear array sensors, analyzes attitude angle variation with time and founds out a linear rule that the pitch angle and roll angle error variy with time. On this basis, a novel method of in-orbit geometric exterior calibration is proposed for geome-tric exterior calibration, which is based on the constant attitude error model and takes into account the amount of attitude errors of linear change with time. Also, a corresponding parameters solution is given. The model and algorithm of this article are verified by using high-precision ground control points and high-resolution satellite imagery. Experiment sindicate that the improved exterior calibration results are better than those of the previous algorithm. Especially, the positioning accuracy of the linear array direction is improved from 17.9 pixels to 1.0 pixel, which shows that the effect of the linear amount of pitch angle error change with time is significant. The positioning accuracy of the flight direction is improved from 5.3 pixels to 3.7 pixels, which shows that the li-near amount of roll angle error change with time is objective reality, but it has a little effect with respect to the linear amount of pitch angle error change with time. By using the proposed method, the image positioning ac-curacy was significantly improved.