Research On SAR Tomographic Imaging Of DEM Assisted Deramping For Urban Building Three-dimensional Points Reconstruction

Interferometric Synthetic aperture Radar technology can obtain ground elevation information model and a wide range of long time surface deformation information,which is widely used in surface settlement monitoring,landslide monitoring and other fields.However,due to the characteristics of synthetic aperture radar side-view imaging,the phenomenon of SAR imaging layover in urban areas is serious,which greatly hinders the application of this technology in information monitoring in urban areas.The multi-baseline tomographic SAR imaging technology can break through this limitation,realize the elevation to resolution ability,effectively identify the ground targets at different heights in the same resolution unit in the layover region,Gets the city’s three-dimensional or even multidimensional information.With the continuous enrichment of high-resolution radar image data at present and in the future,Tomographic SAR imaging technology has shown great potential for application in a wide range of urban infrastructure monitoring,urban safety management and other fields.Tomographic SAR Imaging technology realizes the resolution of elevation direction by forming a synthetic aperture upward in the elevation.The basic processing process includes single sight complex image registration,deramping,phase error compensation and elevation imaging and other main steps.Among them,multi-baseline SAR data is mainly obtained by the repetitive orbit of the Spaceborne SAR system,so the inherent atmospheric phase influence and the accuracy of the preprocessing links such as the timing SAR data registration are very important to the three-dimensional imaging effect of the subsequent tomography SAR.Aiming at the preprocessing of tomography SAR three-dimensional imaging,this paper focuses on the algorithm of deramping processing,and puts forward a DEM assisted deramping processing method,which is applied to the three-dimensional point cloud reconstruction experiment of urban building tomographic SAR.Firstly,the paper introduces the basic theory of multi-baseline interferometric SAR,including the basic theory of interferometric SAR,PSInSAR basic principle and the basic theory of Tomographic SAR imaging,deduces the mathematical model of tomographic SAR imaging in detail,and briefly introduces the basic flow of tomographic SAR technology imaging processing.Then it focuses on the method of tomographic SAR deramping treatment,which mainly includes two kinds of deramping,includes distance deramping method and DEM assisted deramping method.The DEM assisted deramping method proposed in this paper studies the specific technical processing flow,and points out that the key problem is the registration of DEM and SAR images in order to establish the precise connection between elevation direction and azimuth and elevation.Finally,the above method is applied to the three-dimensional imaging experiment of single building tomographic SAR.In this experiment,28 view area TerraSAR image data and three kinds of iconic buildings were used to carry out tomographic SAR preprocessing and three-dimensional imaging processing by two kinds of deramping methods.Finally,comparing and analyzing the experimental results and the precision analysis is carried out based on the Lidar ground laser point cloud data.Experimental results show that the method is right and effective and can provide some reference for multi-baseline tomographic SARdata processing method.