Research On Methods Of Three-dimensional Displacement Resolving Based On Multi-source Insar Data

As increasingly more SAR satellites with different imaging parameters being sent up and the continual emergence of new InSAR techniques,it usually can get plenty of multi-source InSAR(multi-track and multi-sensor SAR images and multiple InSAR techniques)deformation data in the same area.Based on the observations of the multi-source InSAR deformation data,the three-dimensional displacement can be resolved providing more comprehensive information for geological hazard prediction and monitoring.The core research content of this dissertation is the resolving of three-dimensional displacement from InSAR.To circumvent the influence of the factors such as the large gradient displacement,orbit and terrain error,and gross error,the dissertation used the theory and method of modern measurement data processing to eliminate or restrain all kinds of noise caused by the above factors to improve the accuracy of resolving three-dimensional displacement on the basis the extracted effective information from multi-source InSAR deformation data.This provides a way for high-precise resolving three-dimensional displacement.The main research aspects and conclusions of this dissertation included:(1)Based on the systematic summarization of the principle of SAR imaging and InSAR interferometric phase technique,the D-InSAR technique and on the basis of its MT-InSAR technique for monitoring the LOS displacement are introduced,the main data processing principles and processes are given.Then,two methods of MAI technique and Offset-tracking technique for monitoring azimuthal displacement are introduced,and we used the methods to monitor the displacement from BAM earthquake to fully understand the methods and processes of azimuthal displacement monitoring.(2)A method to determine large-gradient three-dimensional ground displacements using an integration of multiple InSAR methods is proposed.The core of the proposed method is that the offset-tracking method is employed to solve for the displacement with the large gradient or phase decorrelation.First,the displacements in the radar line-of-sight directions are obtained from two interferometric pairs with different viewing geometries by integrating the measurements of differential InSAR and offset tracking.Then,the displacements in the azimuthal directions are obtained from two interferometric pairs with different viewing geometries by integrating the measurements of multiple aperture interferometry and offset tracking.Finally,the three-dimensional ground displacement fields are inferred from these four independent,one-dimensional displacements using the least squares method and Helmert variance component estimation.We apply this method to obtain the three-dimensional ground displacement field in the Dongtan mine region.The experimental results indicate that the proposed method can be used to estimate three-dimensional ground displacement fields in mining areas with large-gradient displacement and phase decorrelation.(3)A weight-determining method based on high-precision global positioning system(GPS)observations is proposed.Specifically,the precision of multi-LOS D-InSAR deformation observations is evaluated based on high-precision GPS deformation observations from the same period.Then,considering the influence of random errors(such as orbital errors and phase error due to decorrelation)and systematic errors(such as uncertainty of estimated topography)on the deformation of a pixel observed by multi-LOS D-InSAR,a combined fitting model associated with the positions and elevations of a pixel is built.Finally,the precision of displacement from multi-LOS D-InSAR is evaluated pixel-by-pixel by using the built model.As a result the weights of observations in the model for resolving three-dimensional displacement using multi-LOS D-InSAR can be determined.We verify the feasibility and precision of the weight-determining method through a simulation experiment and a real data experiment,respectively.The verification results show that the proposed weight-determining method based on high-precision GPS observations provides higher reliability for the resolved three-dimensional surface deformation.(4)A method of the robust estimation of the three-dimensional ground displacements based on Helmert variance component estimation is proposed.The three-dimensional displacement was calculated by using the least square method,and pre-residuals of measurements can be obtained.Then,the function between the least squares residuals and the unit weight variance was established.The weight of InSAR displacement measurements was calculated from the unit weight variance.Based on the least squares residuals,according to the equivalent weight principle of the weighted iteration method,the robust estimation of the three-dimensional ground displacements were processed by classifying the measurements into elimination district,reducing weight district and whole weight district.On the basis of summarizing and analyzing the commonly robust estimation based on weighted iteration method,we verify the feasibility and precision of the proposed method through a simulation experiment and a real data experiment,respectively.The verification results show that the proposed robust estimation of the three-dimensional ground displacements based on Helmert variance component estimation can effectively eliminate the influence of the gross error.