Geometry processing and accuracy verification of dual-line array cameras of GF-7 satellite
GF-7 was successfully launched in Taiyuan in November 2019 and is the first sub-meter high-resolution stereo mapping satellite of China.The first domestic star map fusion star sensor is used on the satellite,with dynamic correction of the angle between the two star sen-sors,which can greatly improve the accuracy of satellite attitude determination.Based on the overall design of the GF-7 satellite,this paper studies the key geometric processing techniques in the processing of the GF-7 satellite to achieve high-precision positioning of the High Resolution 7 dual line array camera,and verifies the satellite's geometric level through extensive verifications.Based on attitude measure-ment data and orbit measurement data,the GF-7 satellite has greatly improved its attitude and orbit determination accuracy by using star map fusion star sensors.And the GF-7 satellite has added a unified time system and a unified attitude orbit model,constructing a rigorous geometric model with multiple platforms and cameras.To address the issue of changes in payload pointing angle during the imaging process of the GF-7 satellite,it is not only necessary to ac-curately calibrate the geometric distortion curve of the on-orbit camera,but also to obtain the precise light pointing of each CCD imaging de-tector in the payload to create a high-precision standard image,providing precise internal orientation geometric elements for the production of high-precision standard image products to ensure the internal geometric accuracy of satellite image products.The accuracy of geometric positioning and stereographic mapping products of GF-7 satellite is verified by high precision basic data and field ground measurement points.The high-precision basic data uses the DOM image with a geometric accuracy of better than 1:2000 and the DEM data with a high accuracy of grid and earth accuracy better than 5 m,and the field ground measurement points use 71 ground con-trol points evenly distributed on the image.The verification results show that the uncontrolled positioning accuracy of the camera can be con-trolled to about 6 meters.After introducing a few ground control points to carry out rigid translation,the plane geometric residual is about 1.4 m,and the elevation residual is about 0.86 meters,which meets the demand of high-precision stereoscopic mapping in China.Based on the practical experience of satellite data processing system construction,this paper mainly combines the load design features of GF-7 dual-array camera,studies the key technologies and methods of GF-7 satellite combined processing,so as to improve the research system in the field of high-resolution optical satellite image geometric processing.Finally,a large number of data are used to verify the accu-racy,and the results show that compared with the previous satellites,the geometric calibration accuracy,geometric positioning accuracy and relative geometric accuracy of the front and rear cameras of GF-7 dual-linear array camera have been significantly improved.,reaching the current foreign commercial satellite plane elevation geometric accuracy standards.This indicates that the domestic satellite high-preci-sion satellite load platform and ground processing capacity rose to a new step,which is at the international advanced level and has important practical significance for the subsequent development of related satellite work.
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