Drone Bathymetry

Drone bathymetry uses a small uncrewed aircraft to map shallow-water depth, by green-laser lidar or by structure-from-motion photogrammetry of the through-water imagery. Photogrammetric methods recover depth to roughly 1 to 5 m in clear, calm water by triangulating the refracted seabed across overlapping frames, with a refractive correction near 1.34 applied for the air-water interface. UAV lidar reaches deeper where payload allows. The technique surveys surf zones, reefs, and harbor approaches too shallow or hazardous for a survey launch, bridging the white-ribbon zone, though turbidity, sun glint, and wave action set the working limit. Results feed nearshore charts and coastal-change monitoring.