From TomoSAR Point Clouds to Objects: Façade Reconstruction

Very high resolution SAR tomography (TomoSAR) using multiple data stacks from different viewing angles enables us 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 propose an approach for façade detection and reconstruction from such point clouds. Firstly, the façade region is extracted from the point density projected onto the ground plane. The extracted façade points are then clustered into segments corresponding to individual façades by means of orientation analysis. Surface (flat or curved) model parameters of the segmented building façades are further estimated. Finally, the elevation estimate of each raw TomoSAR point is refined by using its more accurate azimuth and range coordinates, and the corresponding reconstructed surface model of the façade. The proposed approach is illustrated and validated by examples using TomoSAR point clouds generated from a stack of 25 TerraSAR-X high spotlight images from ascending orbit. Results using point clouds from multiple viewing angles, i.e. both ascending and descending orbits, are also presented.