Facade Reconstruction Using Multiview Spaceborne TomoSAR Point Clouds

Kurzfassung

Very high resolution SAR tomography (TomoSAR) using multiple data stacks from different viewing angles enables us for the first time to generate 4D point clouds of the illuminated area from space with a point density comparable to LiDAR. They can be potentially used for façade reconstruction and deformation monitoring in urban environment. In this paper, we present the first attempt to reconstruct façades from this class of data: Firstly, the façade region is extracted using the point density estimates in the ground plane; The extracted façade points are then clustered into individual façades by means of orientation analysis; Surface (flat or curved) model parameters of the segmented building façades are further estimated; The geometric primitives such as intersection points of the adjacent façades are determined to complete the reconstruction process. The proposed approach is illustrated and validated by examples using TomoSAR point clouds generated from stacks of TerraSAR-X high resolution spotlight images from two viewing angles, i.e., both ascending and descending orbits. The performance of the proposed approach is systematically analyzed. To explore the possible applications, we refine the elevation estimate of each raw TomoSAR point by using its more accurate azimuth and range coordinates, and the corresponding reconstructed building façade model. Compared to the raw TomoSAR point clouds, significantly improved elevation positioning accuracy is achieved. Finally, a first example of the reconstructed 4D city model is presented.