Non-Local SAR Tomography for Large-Scale Urban Mapping

Multi-baseline synthetic aperture radar (SAR) interferometric techniques, such as SAR tomography, is well established for 3-D reconstruction in the urban area. These methods usually require fairly large interferometric stacks (> 20 images) for a reliable reconstruction. Hence, they are usually not directly applicable for large-scale 3-D urban mapping using TanDEM-X data where only a few acquisitions are available in average for each city. This work proposes a new SAR tomographic processing framework to those extremely small stacks. The applicability of the algorithm is demonstrated using a TanDEM-X multi-baseline stack with five bistatic interferograms over the whole city of Munich, Germany. Systematic comparison of our result with TanDEM-X raw digital elevation models (DEM) and airborne LiDAR data shows that the relative height accuracy is two meters, which outperforms the TanDEM-X raw DEM. The promising performance of the proposed algorithm paved the first step towards high quality large-scale 3-D urban mapping.