Abstract: [Purposes]Large-scale underwater topographic surveys using unmanned surface vehicles (USVs)often suffer from sparse and unevenly distributed survey lines.The underwater digital elevation model constructed by conventional spatial interpolation methods often has severe terrain expression distortion.Optimizing the underwater terrain modeling method is very important for engineering construction.[Methods]This paper proposes a modeling approach that integrates the fitting of valley-bottom feature lines with the simulation of terrain skeleton structures.Valley-bottom topographic features are extracted through profile projection analysis,followed by the use of rubber-sheeting-based spatial elastic deformation to fit valley-bottom characteristic lines.Contour-based equidistant interpolation is applied to simulate the terrain skeleton,and bathymetric data are used for 3D elevation adsorption.Finally,a progressive interpolation strategy is adopted for modeling.[Findings]Experimental results demonstrate that the proposed model accurately reflects underwater terrain trends and improve the quality of local feature representation.The local fitting accuracy of the model is better than 0.5 m,and the elevation mean square error is less than 5 m.[Conclusions]This method meets the accuracy requirements for national-level 3D real-scene topographic modeling,has been well applied and verified in water resources survey work.

Key words: sparse bathymetric data, underwater topographic modeling, feature fitting, progressive comprehensive interpolation, 3D elevation adsorption, progressive modeling