Radiometric Cross-Calibration of GF-4/PMS Based on Radiometric Block Adjustment

To obtain more abundant target information, the panchromatic and multispectral sensor (PMS) of the GaoFen-4 (GF-4) satellite utilizes five different integration times. The optimal approach for carrying out the integrated processing of absolute radiometric calibration and radiometric difference minimization of PMS images over these five integration times remains an important issue. Therefore, taking the Dunhuang radiometric calibration site (DRCS) in China as the radiometric-transfer platform and treating the Moderate-resolution Imaging Spectroradiometer (MODIS) and Landsat-8 Operational Land Imager (OLI) as the reference sensors, a new radiometric cross-calibration method of the PMS based on radiometric block adjustment (RBA) is proposed. The validation results show that the proposed method can simultaneously maintain high absolute radiometric calibration consistency with the official calibration coefficients published by the China Centre for Resources Satellite Data and Application (CRESDA) and can reduce the radiometric difference between PMS images over different integration times. In addition, the influences of the distribution of the radiometric control points (RCPs), radiometric tie points (RTPs) filter, spectral band adjustment factor (SBAF) correction, and correction of the bidirectional reflectance distribution function (BRDF) on the calibration results are discussed. The total cross-calibration uncertainty is less than 5.21%.