Study On Spaceborne InSAR Calibration And DEM Generation Technology

Spaceborne Synthetic Aperture Radar(SAR)has a wide range applications in acquring surface information.With the rapid growing up of spaceborne SAR technology,the Synthetic Apeture Radar Interferometry(In SAR)technology has also been developing rapidly.In SAR is not affected by severe weather conditions such as clouds and rain,and it is widely used in many fields such as the changes of surface elevation,vegetation coverage and other aspects.Nowadays,the related algorithms of spaceborne In SAR technology are approaching perfection,and its engineering application has become an inevitable trend in the development of radar field.How to extract data of Digital Elevation Model(DEM)quickly and accurately has become an urgent problem to be solved in the development of spaceborne In SAR technology.The interference parameter errors,such as baseline errors,will lead to the “slope” effect in DEM products directly.The diversity of data information(ground control points,external DEM,ICESat/GLAS,etc.)will lead to different calculation methods of calibration parameters and cause in further different DEM product accuracy.At the same time,the spaceborne In SAR system has different working modes of single-base and doublebase,and different transceiver modes will lead to the different methods of target positioning equations during DEM generation.Therefore,both the multi-source data and multi-work mode restrict the acquisition of high-precision DEM products severely.Given the problems above,this paper takes the high-efficiency and high-precision interference calibration and the engineering realization of DEM generation as the core research content,and carries out the following research work:1.We introduce state-of-the-art developments of on-board In SAR technology and interference parameter calibration technology.It is pointed out that the existence of multisource information and single-double-base system working modes will restrict the acquisition of high-precision and high-volume DEM products.Based on the principle of In SAR generating DEM and the basic principle of interference calibration,we express the primary flow of the In SAR technology to obtain DEM.Then,we analyed the interference calibration error parameters that affect DEM accuracy and proposed the interference calibration error model.2.We do research on the two types of interference calibration algorithms which are used commonly of the day,and disscuss about advantages and limitations of those algorithms further.At the same time,the global ICESat/GLAS elevation databse was constructed.In the condition of lacking ground control points,it is proposed to use the high-precision ICESat/GLAS elevation database combined with the Tan DEM-X DEM to estimate the interference parameters so that we can get high-precision DEM products.3.Give the implementation process of the original DEM generation link,and analyze the two core steps of the link in detail: phase-elevation conversion and geocoding.Meanwhile,the three dimensions target positioning model is improved for the single and double base working modes of In SAR system.The improved positioning algorithm can be applied to the two different working modes.4.The software implementation of interference calibration and DEM generation has been given.The two engineering interfaces have been designed in the terms of the input interface,the output interface,and the parameter setting interface of different levels of users.Meanwhile,the robustness and accuracy of the algorithm have been analyzed by using multiple sets GF3 data.In the end,the paper realized the multi-source information interference calibration and DEM generation in engineering application,and some results of the engineering application have been showed.