基于四叉树的全球地形实时绘制方法

摘要

For the demand of the real-time global terrain visualization,a real-time rendering method of global terrain based on quad-tree is proposed.Firstly,an intersection area of scene culling cone and ideal sphere is computed.Secondly,the visible area is subdivided based on the projection area,and a visible set of multi-resolution terrain is obtained.Finally,the resampling of the normalized grids is implemented to eliminate the cranny,as well as to reduce the redundancy of the data.The results show that the algorithm can filter the mass data quickly,and get a multi-resolution terrain visible node set as small as possible,so as to maintain the amount of graphics data during drawing in each frame at a relatively constant degree,and it is basic for real-time display of the global terrain.%针对全球地形实时可视化的需求,提出一种基于四叉树的全球地形实时绘制算法.该算法采用球模型与相机锥面求交的方法,快速得到可见区域,并以可见区域的投影面积为评价准则进行节点细分,得到一个多分辨率地形可见节点集.最后通过对规整网格重采样来实现裂缝消除并大大减少数据冗余量.实验表明:在保证图形显示质量的前提下,该算法可以快速过滤数据,保持每一帧绘制地形数据量相对恒定,是实现全球地形实时显示的基础.