The on-Orbit Calibration Method Based on Terrain Matching with Pyramid-Search for the Spaceborne Laser Altimeter

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, which is one of the most important factors affecting the geometric accuracy of laser altimeter. This paper proposed an on -orbit calibration method based on terrain matching with pyramid-search of spaceborne laser altimeter. Firstly, we used the high-accuracy reference DEM data to match with stripes of point cloud obtained by the geometric location model of laser altimeter, and the optimal matching terrain can be determined by pyramid-search. Then the accurate pointing error of the laser altimeter was acquired. On this basis, the range error was calibrated by separating systematic and random error. After the calibration, the systematic error was effectively eliminated. Using the ALOS-DSM data with 30 meters grid size as reference, the elevation accuracy of the laser altimeter was improved from 100 meters to 2–3 meters. The proposed method provides an effective calibration means without the test site for the spaceborne laser altimeters.