A novel dual-stage BCPO+FRO optimization algorithm for high-quality contour line generation in terrain visualization

Bathymetric contour mapping in inland waterway systems presents significant challenges in balancing data simplification, feature preservation, and visual quality. Traditional single-stage methods address individual aspects but fail to meet comprehensive hydrographic surveying requirements. This study proposes a dual-stage BCPO+FRO algorithm framework that combines Boundary Control Point Optimization and Fluctuation Reduction Optimization. The BCPO stage performs global shape optimization through control point calculation, polygon construction, and iterative smoothing. This process reduces line complexity while preserving bathymetric accuracy. The FRO stage identifies and suppresses local fluctuation features using terrain-weighted indicators and dynamic parameter adjustment mechanisms. This approach improves visual quality without compromising critical underwater terrain characteristics. Experimental validation was conducted on diverse terrain types in the Yangtze River inland waterway navigation channel. Results demonstrate superior performance with substantial turning point reductions, minimal horizontal deviations, and high terrain feature preservation rates. This research provides practical applications for inland waterway management, navigation safety, and hydraulic engineering, and provides technical reference for research on China’s smart water conservancy construction.