Advanced Interferometric Synthetic Aperture Radar (InSAR) techniques such as, Persistent Scatterer Interferometry (PSI) and Tomographic SAR inversion (TomoSAR) including SAR tomography and differential SAR tomography have been proven to be valuable tools for three-dimensional (3D) mapping and deformation monitoring of urban areas. TomoSAR coupled with data from modern SAR sensors, such as the German TerraSAR-X (TS-X), that are characterized by accurate orbit determination and high spatial resolution, produces the most detailed multi-dimensional maps of individual buildings by distinguishing among multiple scatterers within a resolution cell. When using TS-X very high resolution spotlight images, the resulting TomoSAR point clouds have a point (scatterer) density in the order of 1 million pts/km2 which is comparable to the point density of point clouds obtained from Light Detection and Ranging (LiDAR).
One of the limitations of using InSAR techniques, including TomoSAR, for deformation monitoring is that they only measure deformation along the radar Line-of-Sight (LOS) direction. In order to enhance the understanding of deformation, a decomposition of the observed LOS displacement into the real 3D deformation vector in the local coordinate system is desired.
In this paper, we propose a method to reconstruct 3D deformation vectors of urban areas from TomoSAR point clouds available from, at least, three different viewing geometries. Initially, TomoSAR point clouds obtained from multiple viewing geometries are geodetically fused in order to produce an accurate shadow-free detailed point cloud. Then around each scatterer a spatial cube is considered within which the 3D displacement vector of the central point is estimated by L1 norm adjustment. The surrounding points in the cube are participated in the estimation based on the distance they have to the central point and also the standard deviation of the deformation estimate which is the output of TomoSAR.
The methodology is applied on four TS-X very high resolution spotlight image stacks over the city of Berlin from which two stacks are acquired from ascending geometries and two from descending geometries. The linear deformation rate and amplitude of seasonal deformation (induced from thermal dilation of buildings) are decomposed in 3D and the results from some individual buildings with interesting deformation patterns are discussed in details.
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Advanced Interferometric Synthetic Aperture Radar (InSAR) techniques such as, Persistent Scatterer Interferometry (PSI) and Tomographic SAR inversion (TomoSAR) including SAR tomography and differential SAR tomography have been proven to be valuable tools for three-dimensional (3D) mapping and deformation monitoring of urban areas. TomoSAR coupled with data from modern SAR sensors, such as the German TerraSAR-X (TS-X), that are characterized by accurate orbit determination and high spatial resolu...
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