针对GF-1遥感影像的基于影像与基于辐射传输模型的两种交叉定标方法比较

Comparison of the Cross-calibration Methods between Image-based and RTMBRDF for GF-1 Images

"高分一号"配置了4台16m分辨率多光谱宽幅(WFV)相机,组合观测幅宽达到800km。为了将其应用于定量遥感,需要对其进行精确的辐射定标。目前针对高分一号卫星有两种交叉定标方法,都在传统方法的基础上进行了改进。一种是基于影像的交叉定标方法(image-based),另一种是基于辐射传输模型和二向反射分布函数的交叉定标方法(RTM-BRDF)。本文采用这两种方法对高分一号(GF-1)的4个相机进行辐射定标,并对这两种方法进行了对比分析,发现对于WFV2和WFV3这两个近似星下点成像相机,image-based方法可以得到精度较高的辐射定标系数,而对于WFV1和WFV4这两个非星下点成像相机来说,RTM-BRDF方法得到的定标系数精度较高。因此,最终将两种方法结合给出GF-1 4个相机最终的定标系数。

Four wide-field-of-view(WFV)instruments are on board the Gaofen-1(or GF-1)satellite,providing a combined swath of^800km.Before appling to quantitative remote sensing,precision radiometric calibration is needed.Currently,there are two cross-calibration methods.One is the traditional cross-calibration method(image-based),the other is based on radiative transfer model and bidirectional reflectance distribution function(RTM-BRDF).In this study,the two methods were used to cross-calibrate the WFVs of GF-1,and the comparisons were made at the same time.The verification based on satellite data and in situ measurements have shown that,for the two approximately nadir imaging camera WFV2 and WFV3,Image-based method could get higher precision radiometric calibration coefficients,while for two non-nadir imaging cameras WFV1 and WFV4,high precision calibration coefficients would be obtained by the RTM-BRDF method.Finally,the calibration coefficients of GF-1was derived by the combination of the two methods.