An Improved Quadtree of DEM for Terrain Visualization
用于地面可视化的DEM四叉树改进

Quadtree representation of DEM is of importance in DEM compression and terrain visualization. An improved quadtree is proposed.which has the advantages of both an ordinary quadtree and a pyramidal structure. Each node of the improved quadtree is added with a maximum height value and a minimum height value,and the whole quadtree is threaded,thereby making raytracing efficient in terrain visu alization.