摘要
作为我国自主研制的首颗1:10000比例尺立体卫星,高分七号(GF-7)卫星搭载的全波形激光测高仪和双线阵光学相机为全球范围内数字高程模型的建立提供了新的途径。为确定激光脚点在双线阵立体影像中的位置,进而实现两者的复合测绘功能,监视激光指向的足印相机和双线阵相机一般需要在白天同时工作,以确定激光光斑在双线阵相机图像坐标系下的位置。采用同步曝光模式时,足印相机中的光斑图像往往与地物和云层重叠,在强背景噪声条件下由足印相机图像提取的光斑中心精度较差,甚至无法提取光斑中心。基于多轨足印相机图像的分析,激光器在连续工作时,光斑中心随其工作时间的增加在X方向正向偏移并呈现一定的线性,其线性变化规律受激光器出光能量波动的影响;而在Y方向上则基本稳定,可以采用分段线性拟合、数据插值的方式来获取强背景噪声条件下光斑中心的位置,从而提升激光数据的利用效率。激光指向的变化规律也为后续激光载荷系统误差标定与计算提供了依据和参考,也为后续激光测高仪数据的分析和处理提供了新的思路。
The GaoFen-7 satellite(GF-7)is the first 1:10,000 scale stereo satellite independently developed by China.The full-waveform laser altimeter and dual-linear array camera carried by the GF-7 provide a new way of establishing worldwide digital elevation models.The active and passive composite mapping function of the laser footprint and dual-linear array stereo image can be fulfilled when the position of the laser footprint in the dual-linear array stereo image is determined.To this end,the laser footprint camera monitoring the laser pointing needs to work simultaneously with the dual-linear array camera in the daytime to determine the laser spot position in the image coordinate system of the dual-linear array camera.Due to the operating characteristics of the laser footprint camera in the synchronous exposure mode,the spot image overlaps with those of ground objects or clouds.With strong background noise,either the spot center position obtained from an image captured by the laser footprint camera is poor in accuracy,or no spot center position is obtained.According to an analysis of multi-track images captured by the laser footprint camera,when the laser works continuously,the spot center shifts in the positive X direction with the increase in working time and presents linear characteristics that are affected by fluctuation of laser output energy.In contrast,it is stable in the Y direction.Piecewise linear fitting and data interpolation can be used to obtain the spot center position under strong background noise and thus to greatly improve the utilization efficiency of laser data.The variation law of laser pointing not only serves as a reference for later calibration and calculation of systematic errors in laser pointing but also provides a new idea for the analysis and processing of laser altimeter data in the future.
作者
伍煜
龙小祥
杨坚
韩启金
李庆鹏
李松
Wu Yu;Long Xiaoxiang;Yang Jian;Han Qijin;Li Qingpeng;Li Song(Electronic Information School,Wuhan University,Wuhan,Hubei 430072,China;China Center for Resources Satellite Data and Application,Beijing 100094,China)
出处
《光学学报》
EI
CAS
CSCD
北大核心
2021年第23期228-236,共9页
Acta Optica Sinica
基金
对地高分国家科技重大专项(11-Y20A12-9001-17/18,42-Y20A11-9001-17/18)。
关键词
遥感
高分七号卫星
激光测高仪
激光指向
足印相机
强背景噪声
光斑中心
remote sensing
GaoFen-7 satellite
laser altimeter
laser pointing
laser footprint camera
strong background noise
spot center
作者简介
通信作者:李松,ls@whu.edu.cn。
