Geometric Continuity Characterization of Urban Buildings in SAR 3D Imaging Domain and Few-tracks 3D Imaging

Synthetic Aperture Radar (SAR) is an active microwave sensing technology capable of all-weather, day-and-night operation, making it a critical source of Earth observation data. However, conventional two-dimensional SAR imagery often suffers from echo overlap, limiting its effectiveness for target recognition. Although three-Dimensional (3D) SAR imaging using multibaseline observations can mitigate target occlusion, single-pass airborne or spaceborne SAR systems are typically constrained by system complexity, resulting in sparse track sampling that is inadequate for conventional 3D imaging algorithms. To address this limitation, a novel microwave vision–based 3D imaging framework has recently been proposed, in which visual semantic information is extracted and fused to enhance imaging performance. However, the characterization and application of geometric continuity in SAR imagery remain largely unexplored. This study characterizes the geometric continuity properties of typical urban buildings in the SAR 3D imaging domain and proposes sparse-track 3D imaging methods constrained by both implicit and explicit geometric continuity. Experimental results obtained from measured airborne-array InSAR data demonstrate that incorporating geometric continuity constraints effectively enhances 3D imaging performance under sparse sampling conditions. These findings indicate that geometric continuity–based representations provide a practical and effective pathway toward realizing microwave-vision 3D SAR imaging.