Abstract
Abstract. The GaoFen-4 (GF-4) remote sensing satellite is China’s first civilian high-resolution geostationary optical satellite, which has been launched at the end of December 2015. To guarantee the geometric quality of imagery, this paper presents an on-orbit geometric calibration method for the area-array camera of GF-4. Firstly, we introduce the imaging features of area-array camera of GF-4 and construct a rigorous imaging model based on the analysis of the major error sources from three aspects: attitude measurement error, orbit measurement error and camera distortion. Secondly, we construct an on-orbit geometric calibration model by selecting and optimizing parameters of the rigorous geometric imaging model. On this basis, the calibration parameters are divided into two groups: external and internal calibration parameters. The external parameters are installation angles between the area-array camera and the star tracker, and we propose a two-dimensional direction angle model as internal parameters to describe the distortion of the areaarray camera. Thirdly, we propose a stepwise parameters estimation method that external parameters are estimated firstly, then internal parameters are estimated based on the generalized camera frame determined by external parameters. Experiments based on the real data of GF-4 shows that after on-orbit geometric calibration, the geometric accuracy of the images without ground control points is significantly improved.
Highlights
The Chinese GaoFen-4 (GF-4) remote sensing satellite is China’s first civilian high-resolution geostationary optical satellite, which has been launched at the end of December 2015
This paper develops an on-orbit geometric calibration approach for GF-4 to ensure the accuracy, in which a stepwise calibration is performed, external parameters estimated, and
By matching the GF-4’s panchromatic image with the reference digital orthophoto map (DOM) provided by LandSat 8, a number of corresponding point are automatically acquired which can be used as control points for the estimation of panchromatic sensor’s calibration parameters
Summary
The Chinese GaoFen-4 (GF-4) remote sensing satellite is China’s first civilian high-resolution geostationary optical satellite, which has been launched at the end of December 2015. For remote sensing camera of the satellites on low earth orbit (LEO), the traditional on-orbit geometric calibration methods basically use the ground control points (GCPs) generated by matching the satellite images with the reference digital orthophoto map (DOM) and corresponding digital elevation model (DEM) of the high precision calibration field (Gruen, 2007; Takeo, 2009; Leea, 2008). This paper develops an on-orbit geometric calibration approach for GF-4 to ensure the accuracy, in which a stepwise calibration is performed, external parameters estimated, and. After calibration, combined with the star-camera-estimated attitude, every pixel of sensors can obtain a high-precision inertial line of sight (LOS) determined by the external and internal calibration parameters. The proposed calibration model and estimation method have been proven to be stable and effective and could significantly improve the geometric accuracy of GF-4 satellite
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