Exploiting Level-set Implicit Surface Models for 3D SAR Reconstruction

Reconstructing 3D volumes using SAR can be immensely challenging due to limited data collection time and geometry for commonly feasible flight paths. In particular, collecting SAR phase histories densely and widely in altitude is usually infeasible, so standard SAR reconstruction methods suffer from significant sidelobing and/or low resolution. In Phase 1, SSCI demonstrated the feasibility of combining tomographic SAR backprojection methods with surface estimation using level-set implicit surface models to exploit prior knowledge - specifically that X-band radar typically exhibits little surface penetration - to constrain 3D scatterer reconstruction to a narrow surface band. SSCI also demonstrated it could simultaneously estimate the surface from 3D scattering reconstructions. The resulting joint surface and scattering estimates appear may help with applications such as 3D target ID. In Phase 2, we will extend and refine the modular software prototypes from Phase 1 for potential integration with the GOTCHA Radar Exploitation Package (GREP) in Phase 3. BAE Systems will guide development to ensure 3D reconstruction supports GOTCHA needs, including 3D site modeling for accurate DEM reconstruction, 3D clutter characterization and suppression, and 3D target signature fingerprinting for feature-aided tracking. We will accelerate the software prototypes to ensure suitability for integration into GREP applications. BENEFIT: The 3D surface modeling and image reconstruction tools developed under this SBIR have extensive potential for application in a broad range of military and commercial domains beyond the obvious SAR applications. Possible image reconstruction and exploitation applications that could benefit include: sonar applications for underwater exploration and target tracking and identification; seismic methods for geosciences and hydrocarbon and mineral resource exploration; medical imaging using MR, CT, and ultrasound; site modeling using both radar and lidar; border security using EO or IR cameras; and  underground object characterization for applications such environmental remediation with GPR, EMI, and acoustic sensors.