TerraSLAM: Towards GPS-Denied Localization

A long-standing concern with GPS-based location sensing is its vulnerability to satellite signal loss. This may arise from adversarial attacks or natural causes such as urban canyons. Today, there are no real alternatives to GPS for providing absolute global coordinates. We address this concern by introducing TerraSLAM, a new global positioning system that uses a 3D GIS model to bridge relative and absolute coordinate systems, thereby enhancing visual SLAM to function as a global positioning solution. TerraSLAM offers localization accuracy and efficiency comparable to GPS-RTK even in GPS-denied settings. Extensive evaluation on drone localization scenarios shows that TerraSLAM achieves an average global positioning accuracy of 0.21m and a 99th percentile within 0.67m, outperforming advanced GPS solutions by over 70% (0.72m) and 80% (3.62m). Additionally, when integrated with ORB-SLAM3, the localization latency per frame is 16.7ms, achieving a 60% reduction compared to the baseline of 41.3ms. Code is available at https://github.com/cmusatyalab/TerraSLAM.