星载激光光斑影像质心自动提取方法

摘要

The centroid extraction of laser spot images is an important part of satellite laser altimetry data processing,and has significance for obtaining accurate laser pointing angle.This paper summarizes the gray centroid method,Gauss fitting and elliptical fitting method,and compares their advantages and disadvantages.Based on this,a kind of elliptical fitting method combined with the Gaussian threshold is proposed.According to the simulation data test,the accuracy of the method is considerable.Moreover,the real laser spot image-LPA (laser profile array) of GLAS (geoscience laser altimeter system) data is implemented and validated.And the result shows that periodic variation of centroid of LPA is about for 1.5 hours and up to 2～3 pixels,which means the laser pointing angle maybe change 9 arc-seconds and it is necessary to improve the measurement accuracy of laser pointing angle by on-orbit change monitoring of laser centroid position.The conclusions can provide some valuable reference for the footprint images processing of domestic satellite laser altimeter.%激光光斑影像的质心提取是卫星激光测高数据处理中的重要环节,对于获得精确的激光指向角有重要的意义.本文总结了灰度重心法、高斯拟合法以及椭圆拟合法3种常用的质心提取方法,在比较其优缺点之后结合高斯曲面拟合法和椭圆拟合法,提出了一种基于高斯阈值的椭圆拟合方法,针对仿真数据进行试验,有较好的精度结果.采用GLAS(geoscience laser altimeter system)的实际激光光斑影像LPA(laser profile array)数据进行试验,发现LPA光斑质心位置变化周期约为1.5h,幅度最大可达2～3个像素,对应激光指向角变化约9",说明在轨监视激光质心位置变化对于提高激光指向角测量精度非常必要.相关结论可为后续国产卫星激光测高仪足印影像处理提供参考.