Radargrammetric 3-D Reconstruction of Multiple Moving Ship Targets via Multiangle Spaceborne SAR Imagery

The increasing complexity of the marine environments imposes higher demands on the surveillance of maritime ships. Radargrammetry can extract the height information of targets from the amplitude of multi-angle synthetic aperture radar (SAR) imagery, which provides a more specific and accurate description of the ship targets to efficiently enhance maritime surveillance capabilities. However, existing radargrammetric methods are limited to stationary targets, which cannot meet the demands for 3D reconstruction of multiple moving ships in maritime surveillance. To address this problem, a radargrammetric three-dimensional (3D) reconstruction principle and a detailed reconstruction procedure for multiple moving ships via multi-angle spaceborne SAR imagery are proposed in this paper. First, a radargrammetric 3D reconstruction principle for moving targets based on the multi-angle moving-target projection (MAMTP) model is proposed, and its theoretical height reconstruction accuracy is derived. Based on this principle, a multi-angle spaceborne SAR image registration algorithm for moving targets is proposed. Then, a whole radargrammetric 3D reconstruction procedure for multiple moving targets via multi-angle spaceborne SAR imagery based on the proposed principle is developed. This procedure includes the following steps: (i) division and refocusing of received signals from multiple moving targets; (ii) estimation of targets' velocities; (iii) multi-angle spaceborne SAR image registration; (iv) radargrammetric 3D reconstruction. This procedure can achieve accurate 3D reconstruction of multiple moving ships. Simulation results including both scatterer targets and electromagnetic targets verify the correctness of the proposed radargrammetric 3D reconstruction principle and the effectiveness of the proposed reconstruction procedure.