星载多相机拼接成像传感器在轨辐射定标方法

On-orbit Radiometric Calibration Method of Spaceborne Multi-camera Mosaic Imaging Sensor

星载传感器在轨辐射定标是定量遥感的核心和基础,其定标精度将直接决定定量遥感产品的质量。但是对于多相机拼接成像传感器而言,现有在轨辐射定标方法无法实现各相机绝对辐射定标与相机间相对辐射校正的一体化处理。因此,本文以高分一号(GF-1)卫星宽视场(WFV)传感器为例,提出了一种基于改进型辐射区域网平差的在轨辐射定标方法。该方法首先利用传统的交叉定标方法获取WFV传感器各相机的辐射控制点信息,然后在同轨相邻相机影像重叠区域中提取辐射连接点信息,最后在考虑相机间相对辐射校正与绝对辐射定标之间的耦合关系后,采用整体平差的方式同时获取各相机在轨绝对辐射定标系数及辐射约束条件方程参数。试验结果表明采用该方法获得的各波段在轨绝对辐射定标系数的相对误差均优于9.34%,同时利用该定标系数能够实现同轨相邻相机影像间相对辐射校正处理,其重叠区域各波段表观辐亮度差异绝对值的平均值均小于1.63 W·m^(-2)·sr^(-1)·μm^(-1)。

As the core and foundation of quantitative remote sensing,the precision of on orbit radiometric calibration of spaceborne sensor directly determines the quality of quantitative remote sensing production.However,the available radiometric calibration methods have been unable to achieve the absolute radiometric calibration of each camera and the relative radiometric correction among cameras simultaneously for multi camera mosaic imaging sensor.Therefore,taking wide field of view(WFV)multispectral sensor equipped with GF1satellite as example,this research proposes an innovative on orbit radiometric calibration method based on the modified radiometric block adjustment.First,the radiometric control points of each WFV camera are extracted using the traditional cross calibration method.Then the radiometric tie points of adjacent WFV cameras in the overlapping regions are obtained.At last,the integrate adjustment method is used to calculate the calibration coefficients of each WFV camera and the parameters of radiometric constraint equation considering the coupling relationship between the relative radiometric correction and the absolute radiometric calibration.The experimental results show the relative errors of the absolute radiometric calibration coefficients in each band are all less9.34%.Meanwhile,the absolute radiometric calibration coefficients can realize relative radiometric correction among WFV cameras.The average absolute values of top of atmosphere(TOA)radiance differences in the overlapping region of adjacent cameras in each band are all less1.63W·m-2·sr-1·μm-1.