Research On Establishing River Channel DEM Based On Airborne LiDAR And Single-Beam Bathymetry Data

This paper uses airborne Light Detection and Ranging(LiDAR)point cloud data to generate land-based Digital Elevation Model(DEM)in order to provide DEM and support of 3D model data for a water research institution.Digital Depth Model(DDM)is generated by using without tide correction Real-time Kinematic(RTK)single-beam bathymetry data,and DEM is integrated together with DDM to generate water and underwater integrated DEM as well as 3D terrain models.The main conclusions of the paper are as follows:(1)The triangulation iterative encryption filtering algorithm is used to filter the point cloud data in this paper on the research of the construction of the airborne LiDAR point cloud data filtering and measurement area DEM.The ground points are constructed into Triangulated Irregular Network(TIN)by Delaunay triangulation.Linear interpolation method is used to generate the measuring area DEM.The test results show that the method has good universality,less parameter setting and high time efficiency.It is suitable for small scale mapping with large area.(2)The height fitting of bathymetric data is carried out based on EGM2008 "removal-recovery" method,and the accuracy of constructing DDM by four spatial interpolation methods of Spline,Inverse Distance Weighted(IDW),Kriging,Natural Neighbor Interpolation(NNI)is analyzed in this paper.The test results show that spline has better interpolation effect comparing with other three interpolation methods by using shallow water discrete single beam bathymetry data to construct DDM.(3)This paper proposes a method of DEM integration based on optimized grid method in view of the shortcomings of the traditional grid method in integrating DEM data,there is a "pixel gap" in the splicing area.The results show that the method has good smoothing effect in integrated expression of land and water DEM data,as well as applicability and superiority.(4)The error and statistical analysis of DEM is carried out by using the quality evaluation indexes such as root mean square error,fitting superiority and gross error rate in this paper.3D visual analysis are carried out with usage of DEM combining with remote sensing images and contour lines.The results ascertain the limitations of error statistical analysis and necessity of 3D visual analysis.(5)The 3D terrain model of the OBJ format is generated by using the DEM gray scale map.This method has the advantages of high modeling resolution,low computational cost,high efficiency,high data compatibility and low data redundancy.