| Absolute radiometric calibration is the premise and basis for the quantitative application of remote sensing data.The traditional site-substituting calibration has problems such as low calibration frequency,high calibration cost,site heterogeneity,and inability to achieve wide dynamic range calibration.In order to solve the above problems,this paper adopts an automatic calibration algorithm with a wide dynamic range,and based on this algorithm,a calibration software is designed and implemented,which is used to manage the calibration data and realize automatic calibration with a wide dynamic range,so as to quickly obtain the absolute radiometric calibration coefficient of the satellite remote sensor.The thesis is mainly divided into three parts,namely algorithm introduction,software design and implementation,software testing and application.In order to solve the problems existing in the alternative calibration of existing sites,this paper adopts an automatic calibration algorithm with a wide dynamic range in combination with the multi-level gray-scale targets of Songshan fixed target field and the automatic observation equipment.The algorithm includes three parts:processing of field observation data,satellite image processing and radiative transfer calculation.The paper gives a detailed introduction to the calculation process of each part,which lays a theoretical foundation for the design and realization of the calibration software.The software design and implementation part mainly introduces the development technology and process of the calibration software.The software is based on the wide dynamic range automatic calibration algorithm,and is developed by separating the front and back ends based on the B/S architecture.After the software is implemented,the user does not need to install the client,and can access and use the software through a browser.Among them,the front-end uses the Vue framework and the Element UI component library,the back-end uses the Django framework,and uses MySQL as the database.The software includes the functions of registration and login,data upload,data display,data calculation,satellite image processing and calibration coefficient calculation,etc.After the software development is completed,each functional module is tested.The test results show that the software has realized all the expected functions,and each functional module can work normally.Finally,the software was used to the inorbit radiometric calibration of the panchromatic multispectral sensor PMS2 on board the GF-2 satellite to obtain its calibration coefficients,and the calibration results were verified using the automated calibration system at the Dunhuang calibration site and the setting coefficient published by the China Resources Satellite Application Center.The verification results show that the relative deviation between the radiance of the top of the atmosphere channel calculated by the two automatic calibration systems is within 4.3%,which preliminarily verifies the feasibility of the calibration method proposed in this paper and the correctness of the software calculation. |
