Methodology for fine-scale seamless elevation model construction using unoccupied aerial and surface vehicles

Seamless bathymetric and topographic digital elevation models (SBT-DEM) of coastal zones are important for modeling tsunami propagation and coastal inundation, monitoring coastal erosion and deposition, and modeling hydrodynamics and sediment transport. Fine-scale SBT-DEM construction has been elusive due to the difficulty of accurately measuring shallow water depths with conventional techniques. We attempt to perform coastal bathymetric and topographic surveys using an SBES-equipped unoccupied surface vehicle (USV) and a LiDARequipped unoccupied aerial vehicle (UAV), and construct a fine-scale SBT-DEM using GIS (Geographic Information System) techniques. The results show that the proposed spatiotemporal divisional measurement method can seamlessly collect coastal topographic and bathymetric data using tidal range. The improved Blend mosaic algorithm not only seamlessly and smoothly stitches the land and seabed DEMs, but also minimizes the loss of elevation accuracy. The fine-scale SBT-DEM constructed in this paper has the advantages of high resolution (Pixel size = 1 m) and high accuracy (RMSE = 6.2 cm). Fine-scale SBT-DEM can provide integrated topographic and bathymetric data for coastal dynamic monitoring and environmental management