Large-scale urban mapping using small stack multi-baseline TanDEM-X interferograms

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. They are not directly applicable to SAR interferometric (InSAR) stack with only a few acquisitions, as the extremely small number of acquisitions can severely bias the estimates from the spectral estimators, such as beamforming which is often only asymptotically optimal. In addition, the number of images also causes severe ambiguity issue of the pixel with low signal-to-noise ratio. In this work, we propose a new processing framework of 3-D reconstruction with TomoSAR using extremely small stacks. Moreover, the applicability of the algorithm is demonstrated by exploiting TanDEM-X co-registered phase preserving single look slant range complex SAR images (CoSSC) over a large-scale test site of the whole Munich city, Germany. The reconstructed results have been systematically compared with global production of TanDEM-X digital elevation models (DEM) and LiDAR dataset, which show the potential of high quality large-scale 3-D urban mapping.