Detection of Stationary Human Targets on the Ground Using UAV-Borne Fully Polarimetric SAR: Proof of Concept and Preliminary Results

Bio-radar is widely used for casualty search and rescue. However, its short-range and handheld operation mode limits the efficiency of wide-area detection. This paper applies UAV-borne fully polarimetric synthetic aperture radar (PolSAR) to the detection of stationary human targets at long ranges and experimentally validates the feasibility of this framework. To address the difficulty of detecting weakly scattering stationary human targets in strong clutter backgrounds, we propose a novel framework that integrates clutter suppression, target enhancement, and false-alarm suppression. The method introduces, for the first time, polarimetric scattering mechanism analysis into human target enhancement. This improves the SCNR of stationary human targets by approximately 13 dB on average. Then, using neighborhood density features, we reduced the number of non-zero pixels in non-human-target areas (NPINA) by 93.8% and 96.9% in the two passes, respectively. Finally, through dual-pass local binary-map correlation, we obtained the locations of the human targets. This study serves as a proof-of-concept and presents preliminary experimental results on the feasibility of UAV-borne PolSAR for long-range stationary human target detection. The experiment was conducted in a parking lot adjacent to a highway, with three subjects lying supine or prone on a gravel surface, and the scene included buildings such as garages and vegetation such as grass. The experimental results indicate that, under the tested conditions, UAV-borne fully polarimetric SAR is feasible for long-range stationary human target detection. This study expands the application scope of SAR and provides a new technical approach for rapid UAV-based human target detection.