基于数据分层分块的海量三维地形四叉树简化模型

A Model for Massive 3D Terrain Simplification Based on Data Block Partition and Quad-tree

在对比几种典型的地形简化算法的基础上,探索建立一种基于数据分块且适合海量三维地形的局部自适应最优化简化模型(LSOSTM模型)。该简化模型以四叉数模型为基础,针对海量地形进行分层分块组织,构造地形四叉树;根据视点以及局部地形粗糙程度动态地改变地形四叉树节点的分裂或合并状态,实时调整不同地形四叉树节点的显示层次;利用"包围盒"法来判断地形四叉树节点是否需要被绘制;使用广度优先遍历方法解决不同分辨率地形四叉树节点拼接造成的裂缝问题。基于LSOSTM模型构建一个演示系统,实现海量地形数据流畅漫游。

A Local Self-adaptive and Optimized Terrain Simplification Model（LSOTSM）is proposed in this paper by comparing several typical algorithms on terrain simplification.It can be used to organize massive 3 dimensional terrain data with multiple terrain quad trees and display them in real time and multiple resolutions.And,the proposed LSOTSM Model can dynamically split or merge data blocks with quad tree structures according to viewpoints as well as the roughness in local terrain,so that the different level terrains could be displayed in real time by adjusting the different quad-tree nodes in data blocks.In addition,LSOTSM can solve a lot of other problems,such as,the crack problem caused by different resolution grid mosaic of terrain could be resolved by breadth-first search algorithm,and the real time drawing problem could be settled by ＂bounding box＂ algorithm that determines which quad-tree nodes should be drawn,and so on.Testing of a prototype system constructed by the LSOTSM model shows that the proposed model achieved good results and offered a useful reference for further research.