Estimation Of Micro Terrain Deformation In Transmission Corridor Area Using SAR Interferometry

The running state of the transmission corridor plays an important role in the stability and security of the entire operation of the power grid. Monitoring the topography of transmission corridor shows great reference value for maintenance. Since the transmission corridor is often located in mountainous areas, vulnerable to the influence of geographical disasters and bad weather, conventional means of monitoring are usually time-consuming and unstable. Synthetic Aperture Radar(SAR) is a remote sensing technology which works all-time in all weather, which shows great advantages in the inversion of surface information both in military and civilian fields. SAR interferometry technique is developed to monitor surface deformation by using the image phase information of SAR images. The permanent scatterers interferometry(PS-InSAR) can investigate ground deformation of urban areas, mining subsidence, earthquakes and other surface deformation with the with centimeter accuracy. However, the technology requires a large amount of images, and can not get good results in topography non-urban areas which covered with vegetation. The main content of this article is investigating the deformation of transmission corridor by using SAR images, and then verifying the results.Since the transmission corridor usually locates in topography areas covered with vegetation, the PS-InSAR technology can not extract the ground surface micro deformation information due to the lack of enough permanent scatterers. In this paper, some progresses are proposed in the selection of stable scatterers in the PS-InSAR technology, and then applied to the extraction of surface subsidence by using seven full polarization Radarset-2 images. Firstly, the paper analyses the basic theory of SAR and InSAR technique. Secondly, a new algorithm of selecting permanent scatterers by binding traditional selection methods are proposed,which can extract enough number of reliable permanent scatterers by using few full polarimetric SAR data. Meanwhile, improved selection algorithm is proposed to selected distributed scatterers(DS points),which shows great advantages in running time and solves the problem of insufficient number PS points in non-urban areas. Subsequently, two kinds of measurement points are combined and processed, the phase component of linear deformation can be extracted by unwrapping the phase of stable scatterers Then the phase of nonlinear deformation and atmosphere can be extracted by the same way. Thus the strain information of each stable scatterer is extracted. Finally, we verify the results by comparing the correction value of elevation and external high-precision elevation. The results show that the PS-InSAR technology with proposed algorithm can extract the micro deformation information of the transmission corridor area.