Research On Construction Method Of 3D Multi-resolution Model Of Complex Terrain

Complex three-dimensional terrain can intuitively describe various terrain features of the surface,which is widely used in Forestry GIS and digital earth to assist spatial analysis and data simulation.The traditional multi-resolution model building method does not consider the data distribution characteristics of complex terrain,which has the problems of low efficiency and difficult management.The goal of this paper is to study the construction and management method of multi-resolution model of complex 3D terrain data,explore the whole process of terrain data generation to application,and propose a more efficient method of terrain model construction to facilitate client management and scheduling.Aiming at the construction and management methods of 3D multi-resolution model of complex terrain,this paper studies the terrain triangulation generation,multi-resolution model construction and data cache management technology.Firstly,this paper takes the contour map as the data source and improves the traditional point by point insertion method.In this algorithm,the discrete elevation points are presorted to make the insertion order conform to the spatial autocorrelation criterion.Combined with area coordinates and memory search,the number of triangle retrieval in the process of terrain network construction is greatly reduced.The experimental results show that the time-consuming of this algorithm is less than the traditional algorithm,and the efficiency of terrain generation is improved.Secondly,in the process of multi-resolution terrain model construction,this paper uses the improved triangle folding method to simplify the models at all levels,and the folding cost is determined by the volume error and terrain relief,which improves the efficiency of terrain model simplification.The quadtree structure considering the data density is used to divide the terrain space and establish the spatial index to get the terrain block with more balanced data.At the same time,the stitching information of the block boundary is encoded to effectively eliminate the cracks between blocks.Thirdly,for the cache management of terrain data,this paper proposes a prediction region algorithm for terrain block cache replacement,which fully combines the spatial characteristics of data access,greatly improves the cache hit rate and reduces the waiting time of users.The prototype system is based on C + + and the 3D scene rendering is based on Open GL.The efficiency of the algorithm and the usability of the scheme are verified by experiments.