Research On Radiometric Cross Calibration Method Of Domestic Remote Sensing Satellites Considering Imaging Geometry

With the development of remote sensing in China,remote sensing technology plays a more and more important role in national defense construction and national economic construction.The demand for remote sensing applications has also gradually evolved from qualitative to quantitative.Radiometric calibration is the basis of quantitative remote sensing.Thus,it is becoming increasingly urgent to acquire radiometric calibration coefficients of domestic remote sensing satellites.Site calibration is too complicated to restrict the calibration frequency once a year.Therefore,it is urgent to develop other vicarious calibration methods.The radiometric cross calibration which based on near synchrotron imaging is used to calibrate satellite sensor taking another satellite sensor as reference.This calibration method can avoid complex synchronization measurement data acquisition operation with less manpower and material input to obtain relatively high accuracy of radiation calibration.It can also achieve the calibration of historical data.Taking the high-resolution satellite GaoFen-1(GF-1)wide-field-of-view camera(WFV)as an example,the radiometric cross calibration of domestic remote sensing satellites is studied in this paper.The main work and innovation of this article are as follows:(1)Considering the disadvantages for large imaging angles of wide range cameras which were rarely mentioned in existing radiometric cross calibration methods,a method of sample point evenness evaluation and a method of precise matching strategy based on local matching were proposed on the basis of summarizing the current research status and research ideas of wide range camera at home and abroad.The more accurate imaging geometry angle information was obtained by recalculating the imaging geometry of the sample points.Radiometric cross calibration requires higher uniformity of sample points and higher matching accuracy of sample pairs.In this paper,the measurement index of the uniformity of sample points was formulated,and the strategy of obtaining a certain number of feature points by using the scale invariant feature transformation SIFT algorithm was used to match the sample points based on the feature point distance and the sandwich angle weighting.(2)A technical framework and the method flow of radiometric cross calibration for wide range camera was proposed.The validity of the method was verified by experiment taking Landsat 8 OLI and GF-1 WFV as an example.A radiometric cross calibration was conducted by taking the Landsat 8 OLI sensor as a reference to obtain the radiometric calibration coefficients of the GF-1 WFV1 camera based on the synchronous image pair received on October 15th,2014.The exact matching sample points and the imaging geometry angles of the pixels were obtained based on the above method.The spectral response function(SRF),the pixel elevation,the atmospheric parameters and the aerosol optical thickness(AOD)were synthesized,and the apparent radiance of the GF-1 WFV1 was simulated by the 6S radiation transmission model.Furthermore,the radiometric calibration coefficients of the GF-1 WF V1 camera were further fitted.(3)The reliability of the radiometric cross calibration coefficients was examined using the surface synchronous measurement data.It was proved that the method can be extended to the radiometric calibration of domestic satellites with high resolution.Based on the ground spectral data and the GF-1 WFV1 image covering the SongShan city of Henan Province in October 24th,2014,the equivalent surface reflectance on the imaging date was interpolated through the preprocessing of spectral data.The surface albedos of multiple sample regions with various ground types were compared with the surface reflectance after the atmospheric correction.The comparison results showed that the radiometric cross calibration coefficients obtained in this paper are more suitable for quantitative application compared with the coefficients published by the China Center for Resource Satellite Data and Application(CCRSDA),which validated the feasibility of this method.Considering the special imaging geometry of the GF-1 WFV1 camera,the technical framework and method of the radiometric cross calibration of the wide range camera are also suitable for other domestic remote sensing satellite sensors,having the generality.