大区域地形可视化技术的研究

近年来，地形场景的实时绘制已受到人们越来越广泛的关注，目前已经提出的一系列场景加速绘制算法,虽然在不同的应用场合也取得了一定的效果，但都存在着局限性，尚不能满足大区域地形环境的实时高速绘制的要求，而与其密切相关的技术主要涉及到地形多分辨率表示、海量地形数据和纹理数据的分页管理、地形和纹理数据的LOD控制、地形和纹理数据的快速存取和更新等．为了能够对地形场景进行实时绘制，在对大区域地形数据管理和实时绘制技术进行研究和试验的基础上，对构建视相关动态多分辨率模型的方法进行了改进，实现了地形模型多分辨率表示与视相关的有机结合，并提出了一种高效的场景数据存取方法，进而实现了一个整合自适应三角网剖分、地形场景数据分页管理和动态更新等相关技术于一体的地形三维可视化系统，试验结果表明，该算法能够实时绘制地形场景，且质量较好．

The Research of Large Scale Terrain Visualization

Real-time rendering of landscape has attracted growing interesting in recent years. The existent accelerating methods of 3D terrain rendering have made their contributions to terrain visualization, but, they have themselves drawback, especially for large scale terrain visualization at interactive rate. Large scale terrain visualization contains the following contents: terrain multi-resolution representation, terrain and texture paging, terrain and texture LOD control and efficient data store and retrieve. Based on the research about management and real-time rendering of large scale terrain data, one method of generating multi-resolution terrain model is improved, which combines the representation of terrain multi-resolution model with view-dependent control. A new method of storing and retrieving terrain data by quadtree is proposed. Furthermore, an all-in-one terrain visualization system which integrates adaptive triangulation, dynamic scene paging and data updating is realized. At last, some experiments have been presented to verify the work done in this paper.