TomoSAR Three-Dimensional Image Restoration in Urban Area by Multipath Exploitation

SAR Tomography can provide three-dimensional (3D) image of the observed scenes, becoming an important technology for urban mapping, target detecting and many other fields. When imaging urban scenes, multipath signals are always considered as noise in the previous research on 3D SAR imaging. However, the signals experienced multiple bounces hold massive information about the target scenario. In this paper, we aim to turn "waste" into treasure by digging for the hidden information in multipath. Based on the TomoSAR mechanism, we complete the restoration of the 3D imaging result. Firstly, we introduce the TomoSAR imaging model under the low-altitude case, which is more suitable for airborne or UAV- borne platform in urban area. We analyze the multipath model and propose the multipath detection and restoration methods. The virtual targets caused by multipath can be restored to the correct positions in the image by relocating. To verify the validity of our method, we conducted a series of real-data experiments, the results show that our method makes full use of multipath signals to retrieve non-line-of-sight targets missing in traditional direct-path 3D imaging.