Seabed Fingerprinting for Maritime Navigation in GNSS-Denied Environments

Abstract

Maritime navigation relies heavily on Global Navigation Satellite Systems (GNSS), yet military surface vessels must remain operational when satellite signals are unavailable, degraded, or denied. In such GNSS-denied environments, Inertial Navigation Systems (INS) accumulate unbounded drift, while existing Terrain-Aided Navigation (TAN) methods remain sensitive to terrain distinctiveness and are rarely evaluated for surface vessels. We present SAND-E, a particle-filter framework for seabed-aided maritime navigation that treats seabed fingerprinting as an image matching problem. Near real-time Multibeam Echosounder (MBES) measurements are matched against bathymetric reference maps using Normalized Cross-Correlation (NCC), SuperPoint+LightGlue (SP+LG), or a combined prior-gated method, and the resulting position fixes are fused into the particle filter for recursive state estimation. Evaluated on North Sea and Atlantic Ocean bathymetry, NCC outperforms SP+LG across all metrics, achieving an RMSE of 92.1 m, a 100% fix rate, 92.6% of runs within 500 m, and a runtime of 0.5 ms per fix. The combined method matches NCC under nominal conditions but provides additional robustness with an outdated reference map, where the prior gate rejects degraded NCC fixes and falls back to SP+LG. The framework generalizes across three geographically distinct test areas, remains viable with a three-year-old reference map, and reduces average final position error from Dead Reckoning (DR) to 115.3 m, demonstrating seabed fingerprinting as a viable infrastructure-independent navigation solution for GNSS-denied military surface vessels.