资源三号02星激光测高仪在轨几何检校与试验验证

摘要

我国在资源三号02星上首次搭载了一台用于对地观测的试验性载荷——激光测高仪,开展对地观测的激光测高试验.由于卫星发射时的振动以及入轨后空间环境变化等因素影响,激光测高仪的指向、测距等系统参数相对于发射前地面测量值可能发生变化,从而引起激光的平面和高程误差.本文根据资源三号02星激光测高仪特点,提出了一种基于地面探测器的在轨几何检校方法,该方法构建了以指向、测距为系统误差的严密几何检校模型,以激光测距值残差最小为原则,利用地面探测器捕获的激光光斑位置作为参考,实现系统误差参数高精度在轨几何检校.利用卫星在轨测试期间多个试验场数据进行检校后,以有关DEM数据作为地面参考比对,地形坡度小于2°区域内的激光点高程精度由检校前的100~140m提高到2~3m.利用平坦地区激光足印内少量GPS外业控制点进行验证对比,检校后激光高程测量的绝对精度优于1m.试验结果表明了资源三号02星激光测高仪在轨几何检校方法的有效性和正确性.%ZY3-02 is the first satellite equipped with a laser altimeter for earth observation in China.This laser altimeter is an experimental payload for land elevation measurement experiment.The ranging and pointing bias of the laser altimeter would change due to the launch vibration, the space environment difference or other factors, and that could bring plane and elevation errors of laser altimeter.In this paper, we propose an on-orbit geometric calibration method using a ground-based electro-optical detection system based on the analysis of ZY3-02 laser altimeter characteristic, and this method constructs the rigorous geometric calibration model, which consider the pointing and ranging bias as unknown systematic errors, and the unknown parameters are calibrated with laser spot's location captured by laser detectors and the minimum ranging error principle.With the ALOS-DSM data as reference, the elevation accuracy of the laser altimeter can be improved from 100~150meters before calibration to 2~3meters after calibration when the terrain slope is less than 2degree.With several ground control points obtained with RTK in laser footprint for validation, the absolute elevation precision of laser altimeter in the flat area can reach about 1meter after the calibration.The test results demonstrated the effectiveness and feasibility of the proposed method.