Research On Multiple Loads On Orbit Calibration And Evaluation Methods For Optical Satellites

The calibration of optical satellites is an important technology to ensure that satellite sensors obtain accurate remote sensing image data.The calibration accuracy directly determines the product quality of remote sens ing satellites.To improve the imaging quality of satellites,a variety of calibration technologies have been studied at home and abroad,including visible band cameras,infrared cameras,and hyperspectral cameras.There are also a variety of calibration m ethods,such as site calibration,radiation calibration,and cross-calibration.Aiming at the characteristics of complex and difficult multi-load calibration technology of optical satellites,this dissertation proposes a comprehensive calibration method th at meets the requirements of “synchronous calibration of three loads and complimentary verification of multiple calibration methods of the same load”.By participating in the development and construction of a satellite multi-load optical imaging calibration system,the on-orbit calibration of spaceborne infrared and hyperspectral has been successfully realized,which provides a good basis for satellite delivery and quantitative application.Firstly,this dissertation starts with the common calibration techn ology of the visible camera,and combs the structure of the whole positioning system by introducing the common satellite coordinate system;By using the image matching technique,the optical axis pointing calibration model of visible light camera is analyzed,and then the on-orbit calibration of optical axis pointing of visible light imaging satellite camera is realized by using high-precision image matching algorithm and robust solution method of calibration parameters.At the same time,the rolling iteration method is used to improve the real-time on-orbit performance and the geometric positioning accuracy of the optical satellite system.Secondly,according to the radiation sensing characteristics of the infrared camera,the basic principles and methods of site calibration and cross-calibration are studied.The absolute radiation calibration method on semi optical path satellite and the site absolute radiation calibration method based on the multi-temperature field are proposed to realize the real-time and high-precision absolute radiation calibration of the high-resolution infrared camera.By analyzing the radiation uniformity,radiation temperature difference,and noise statistical characteristics of ground objects,a noise statistical model for the comprehensive comparison of optimized structure function method and differential noise method is established,to realize the temperature resolution evaluation of spaceborne high-resolution infrared camera based on typical ground objects.Thirdly,a high-precision pupil radiance calculation method under different spectral response functions and different site conditions is proposed by analyzing the principle of space-borne hyperspectral imaging and the principle of hyperspectral radiometric calibration.It thus solves the problem of optimal design of test schemes including multiple reflectivity sites and high-precision test area indication.The on-orbit high-precision absolute radiometric calibration of spaceborne high-resolution interferometric imaging spectrometer is realized.Finally,a comprehensive calibration method meeting the requirements of“synchronous calibration of three loads and complimentary verification of multiple calibration methods of the same load” is proposed to deal with the aiming at the problem of comprehensive calibration of optical satellites equipped with different bands cameras in engineering practice.The proposed method is comprehensively applied to the whole process of calibration test of a satellite application system,satellite on-orbit test,and on-orbit calibration,Then,the on-orbit test and quality evaluation of the satellite has been carried out,and several index tests have been completed.At the same time,the comprehensive performance of the satellite is evaluated,which provides the basis for satellite delivery and technical support for satellite index determination and system optimization.The infrared calibration test has been carried out,and the optimization process of mutual supplement and verification between infrared satellite long-term calibration and site high-precision calibration has been realized.In addition,the hyperspectral calibration test has been carried out,and the multi-point test method has been used to ensure the reliability and credibility of the calibration coefficient,to provide a guarantee for the follow-up processing of the two new loads,and satellite application.This is of positive significance to further improve the product quality of the satellite.