高分七号星载激光测高仪在轨几何检校与精度评估

高分七号卫星（GaoFen-7, GF-7）搭载了我国首台正式用于对地观测的星载激光测高仪，其测高精度备受国内外关注。文中系统性介绍了基于地形匹配、单片足印影像以及地面探测器阵列的3种检校方法，并利用同一地区GF-7星载激光数据，分别进行不同检校试验与验证，对比和分析3种不同检校试验后GF-7星载激光测高仪的高程测量精度。结果表明，基于地面探测器阵列的检校方法精度最高。以高精度机载LiDAR点云作为地面验证数据，GF-7星载激光测高仪经检校后波束1精度达到0.177 m，波束2为0.157 m；受限于检校所用的参考数据精度不足，其他2种检校方法精度相对较低，测高精度达到0.8 m。

In-orbit geometric calibration and accuracy evaluation of GaoFen-7 spaceborne laser altimeter

The GaoFen-7 satellite (GF-7) is equipped with China’s first spaceborne laser altimeter, which is officially used for earth observation, then its measurement accuracy of surface elevation has attracted much attention at home and abroad. Three calibration methods for spaceborne laser altimeter: the terrain matching calibration method, the single laser footprint image calibration method, and the ground detector array calibration method were introduced systematically. The above calibration methods of spaceborne laser altimeter were also used to carry out calibration test for GF-7 spaceborne laser altimeter with the same set of data. After laser calibration, the elevation measurement accuracy of GF-7 spaceborne laser altimeter was evaluated and analyzed under the results of three calibration methods. The airborne LiDAR point cloud data was employed for accuracy verification. The results show that the spaceborne laser altimeter calibration method based on ground detector array has the highest accuracy, which spaceborne laser elevation measurement accuracy of GF-7 laser beam 1 is 0.177 m, and the laser beam 2 is 0.157 m. Limited by the elevation accuracy of the reference topography data for spaceborne laser altimeter calibration, the elevation measurement accuracy of the other two spaceborne laser calibration methods is relatively low, which can just achieve 0.8 m.