Error Analysis and Preliminary Pointing Angle Calibration of Laser Altimeter on Ziyuan-3 02 Satellite

The Ziyuan-3 02 satellite (ZY-3 02), which is the second domestic stereo mapping satellite in China, was launched at May 30, 2016. Apart from optical cameras, the ZY-3 02 satellite carries the first Chinese satellite laser altimeter for Earth observation. During orbiting, the ZY-3 02 has obtained a certain amount of laser altimeter data. Based on this data, we analyze the error sources and conducts preliminary pointing angle calibration. In this paper, comprehensive analysis of the error sources is presented according to the rigorous geometric model of satellite laser altimeter, which shows that the bias of laser pointing contributes most to the height error of laser footprints. Then, a novel method for preliminary laser pointing calibration method without field surveying is proposed and its mathematical model is presented. After that the open source topographic data(AW3D30 DSM) is used to rectify the laser pointing angle. Experimental results indicate that the rectified pointing angle based on exist topographic data can improve the height accuracy from more than ten meters to less than 3 meters. Thus the error analysis is proved to be right and the preliminary laser pointing calibration method to be useful. The proposed method gives a way to eliminate the coarse errors of laser footprint location and strongly supports the ground calibration of satellite laser altimeter which will farther improves the positioning accuracy of laser footprints.