InSAR Data Source Selection Based On Terrain Factors And Landslide Deformation Analysis

In recent years,Synthetic Aperture Radar Interferometry(Interferometry SAR,InSAR)has been widely used in the investigation and monitoring of hidden danger points of earth disasters by virtue of its ability to accurately obtain large-scale surface deformation.However,InSAR technology currently has some problems in landslide monitoring in Southwest China.The reason is that the complex terrain undulations in the southwest cause overlap and shadow errors,and the significant atmospheric changes in the southwest reduce the coherence of InSAR data interference,which seriously affects the accuracy of landslide deformation information extraction.The existing InSAR technology is in high landslides.In-depth research is still needed in precision monitoring.This paper takes the Xinpu landslide in Chongqing as the research object,and uses the sentinel 1 data to study the landslide deformation analysis method.First,the untrustworthy area of the study area is extracted by combining the sentinel satellite parameters and the slope and aspect topographic factors;then,according to the characteristics of the atmospheric effects in Chongqing area,based on the external data GACOS(Generic Atmospheric Correction Online Service for InSAR,GACOS)atmospheric correction method Atmospheric correction is performed on the results of deformation analysis.The specific research content of this paper is as follows:(1)Research on the accuracy of terrain factor extraction under different grid scalesBased on the currently widely used SRTM DEM data,this paper uses slope and aspect as indicators to divide different terrain grid sizes for quantitative analysis,and discusses the influence of different DEM grid sizes in digital terrain on the extraction of slope and aspect.Through analysis,the most suitable grid size for the research area is found,and the terrain description and terrain information loss rate under this grid size are verified.This process can effectively assist the subsequent overlay and shadow area extraction.(2)Geometric distortion region extraction based on local incident angleIn view of the severe overlap and shadow areas of radar images in the southwest mountainous area,in order to eliminate the impact on accuracy of landslide monitoring,the data sources are optimized based on this area.This paper combines topography(slope,aspect)and InSAR data source parameters to integrate factors such as the sensor's perspective,terrain slope and aspect.Since only sentinel 1 data is acquired,the local incidence angle of the data is analyzed.For the relationship between the backscattering coefficient and the backscattering coefficient,the area with a local incidence angle of 10-70° is regarded as a credible area,and other areas are regarded as unreliable areas.And according to the subsequent InSAR data processing requirements,it can be used as a mask to remove,so as to better reduce the error caused by the terrain and improve the credibility of the effective monitoring data.(3)Research on the accuracy of atmospheric correction based on GACOSIn the process of radar data processing,based on the GACOS atmospheric correction method in the southwest mountainous areas where atmospheric changes are more obvious,the permanent scatterers InSAR technique(PS-InSAR)is used to perform atmospheric correction on the study area to obtain before and after removing atmospheric errors.The results of the landslide deformation,combined with the GNSS point measured data for comparative analysis,concluded that: in areas with large terrain undulations and severe atmospheric effects,a good correction effect is shown,which can effectively remove most of the atmospheric delay errors.