Application of SLAM laser scanner in combination with unmanned surface vessel for river surveying

Abstract

Large-scale river ecological restoration requires integrated above-water and underwater topographic data. Existing survey technologies including UAV photogrammetry, separate backpack SLAM and independent USV bathymetry suffer vegetation occlusion, UAV no-fly limits, asynchronous land-water data and qualitative accuracy evaluation, forming clear research gaps: few studies construct synchronous SLAM-USV acquisition framework, lack standardized coordinate/time synchronization and multi-source fusion workflow, and rarely adopt dual independent benchmarks for quantitative precision verification. This paper proposes an integrated survey system combining handheld Lingguang Lixel L2 SLAM scanner and Huace Apache3 Pro single-beam USV. Full reproducible procedures are elaborated, including seven-parameter geotransformation, IMU time synchronization, two-stage point cloud filtering, land-water boundary matching and hybrid Kriging-IDW interpolation. A 2 km river reach in Fujian is tested, with complete environmental parameters recorded for generalization analysis. Terrestrial planar RMSE=0.016 m, elevation RMSE=0.025 m; underwater elevation RMSE=±0.019 m, fully complying with JTS 131-2012 standard. Compared with traditional RTK-sounding survey, labor input drops by 75% and total working time shortens by 81.8%. This integrated method shows unique advantages in narrow silty channels, dense woodland and GNSS weak zones, providing a replicable solution for river regulation mapping.