Through-Water Dense Image Matching for Shallow Water Bathymetry

The introduction of Dense Image Matching (DIM) has reactivated the interest in photogrammetric surface mapping, as it allows the derivation of Digital Elevation Models with a spatial resolution in the range of the ground sampling distance of the aerial images. While the primary field of application is wide-area mapping of topography and urban scenes, charting bathymetry of clear and shallow water areas is equally feasible via application of multimedia photogrammetry. The article specifically investigates the potential of through-water DIM for high resolution mapping of generally low textured shallow water areas using modern techniques like semiglobal matching and off-the-shelf software. In a case study, the DIM-derived underwater surfaces of coastal and inland water bodies are compared to concurrently acquired laser bathymetry data. With an achieved penetration depth of more than 5 m and deviations in the dm-range compared to the laser data as reference, the results confirm the general feasibility of through-water DIM. However, sufficient bottom texture and favorable environmental conditions are a precondition for achieving accurate results.