A Fast Sound Ray Tracing Method for Multibeam Bathymetry Combining Sound Velocity Profile Simplification and Template Interpolation

When performing sound ray-trace process of the multibeam echo-sounder system, high-density sound velocity profiles (SVPs) usually cause significant time consumption in the tracing process due to layer-by-layer accumulation, which is unfavorable for fast and high-precision calculations of massive multibeam bathymetric data. Therefore, this paper proposes a fast sound ray-trace algorithm combining SVP simplification and template interpolation. First, using equivalent SVPs as constraints, the idea of triangulation is introduced, and a weighted average method is flexibly used to combine angular cost and distance cost to remove redundant points in the SVP and reduce the number of SVP layers, ensuring the accuracy of sound ray tracing while preserving key acoustic features. Then, the simplified SVP is used to construct a virtual beam sound ray-trace template. According to the actual beam incident angle and propagation time, the inverse distance weighted interpolation method is adopted to calculate the depth and horizontal distance of the beam to be tracked, replacing the conventional calculation process of massive layered accumulation and improving the efficiency of sound ray tracing for massive beams. The results show that compared with the traditional constant gradient sound ray tracing method, this method has a water depth deviation of approximately 0.34‰ in the shallow water area with an average water depth of 32 m, and the calculation efficiency is increased by 2.9 times. In the deep water area with an average water depth of 4100 m, the water depth deviation is approximately 0.1‰, and the calculation efficiency is increased by 16.7 times, significantly improving the calculation efficiency while ensuring the accuracy of sound ray tracing. The research method can provide a reference for real-time and fast multibeam data processing on platforms such as unmanned surface vessels and autonomous underwater vehicles.