【作者】 姚华；

【导师】 王玉琨；

【作者基本信息】 河南理工大学 ， 计算机应用技术， 2010， 硕士

【摘要】 地形三维可视化技术一直以来是地理信息系统(GIS)、虚拟现实(VR)、计算机图形学等领域研究的热点。本文针对当前地形三维建模及可视化技术的研究现状,围绕着地形数字模型的建立、地形模型简化以及地形多分辨率模型构建等关键技术内容展开讨论与研究,目标是由离散数据构建地形数字化模型并且实现三维地形的可视化模拟。主要完成了如下研究工作:(1)在离散数据构建地形数字模型方面,研究了地形数字高程数据的获取方法与DEM的地形表面建模方法。(2)在分析了常用三角剖分算法的基础上,针对大规模离散数据生成三角网速度较慢的问题,提出了一个改进的三角网生成算法,先将离散点集进行自适应分块,然后对每一块进行三角剖分,最后对所有的子三角网的进行归并,以生成覆盖全区域的三角网模型。(3)针对用计算机处理复杂的地形模型时,在显示、渲染、存储等方面存在着很多困难,为了解决这些问题,提出了一个改进的基于渐进网格的模型简化算法。算法是根据实际的地形的特征,给出了边优先级和点重要度的计算方法,通过确定地形三角网中每条边的优先级,删除的一些重要度小的点,以实现地形模型的简化。(4)根据视点的位置,构造了基于TIN的地形多分辨率模型。最后,本文根据上述研究的基础上,结合视区裁剪算法与任意方向的漫游方法,实现了基于离散数据的三维地形模型建立与地形实时模拟显示。更多还原

【Abstract】 Three-dimensional (3D) terrain visualization is always a hot topic in Geographic Information System (GIS), Virtual Reality (VR), Computer Graphics and other related fields. According to the current research situation of 3D terrain modeling and visualization technology, this thesis focuses on discussion and research of the key modeling technology , digital terrain modeling, terrain model simplification and construction of multi-resolution modeling. The thesis aimed to construct digital terrain modeling by discrete data, and to realize the simulation of 3D terrain surface. The main research results are summarized as follows.(1) DEM data acquisition method and terrain surface modeling method are researched in the construction of digital terrain model by discrete data.(2) On the basis of common Delaunay triangulation algorithm analysis, to solve the existing problems of low speed that triangle network building with large scale discrete data, an improved algorithm is presented in this thesis. First, discrete points are adaptively divided into many sub-blocks, then the discrete points in each sub-block are triangulated, fnally all of the sub- triangulation network are incorporated into together, in order to construct triangulation model that covers the whole area.(3)When these complex models are dealt with by computer, there are many difficulties such as display, rendering, storage and so on. In order to solve these problems, this thesis presented an algorithm of simplification for terrain model based on progressive meshes. The calculation methods of priority of edge and importance degree of point are provided in the improvement algorithm by real terrain feature, the algorithm determines the priority level on each edge and delete some less important degree point in the terrain triangular mesh, to realize the simplified terrain model.(4) According to the position of viewpoint,the terrain multi-resolution model based on the TIN is constructed in this thesis. Finally, based on research above, combining with Clipping Algorithm of visual areas and arbitrary direction roaming method, this thesis realized the 3D terrain modeling and real-time simulation of terrain based on discrete data.更多还原