高精度高速度曲面建模的3维地表模拟和漫游算法

三维真实感地形场景是生态系统模拟、虚拟地理环境和三维GIS不可或缺的要素，而高精度高速度曲面建模方法可以动态实时构建高精度曲面模型。论文引入高精度高速度曲面建模方法，提出了一种可以动态生成地表模型并实时绘制和漫游三维真实感地表的方法。该方法实时动态建立高精度DEM，结合改进的视点依赖多分辨率绘制方法，随视点改变动态重建并绘制当前DEM。首先建立当前可见场景的DEM，然后通过依赖于视点的简化等处理建立层次细节模型，进行实时场景绘制和漫游，随视点改变，在当前场景基础上动态加点和减点更新DEM及层次细节模型，生成当前可见场景，以次循环。实例测试表明，算法可产生真实感较强的场景，实时漫游效率较高，模拟精确。

3D Simulation and Walk-through Algorithm of terrain based on HASSM

Real-time generation of realistic 3d-terrain is essential in ecosystem modeling ,virtual geographical environment and 3d GIS. Based on HASSM, that is , high accuracy and speed surface modeling(HASSM),which can be used to construct surface model dynamically, a new real-time simulation and walk-through method is proposed for constructing terrain model and rendering in real time. Firstly, the current visible terrain model is constructed accurately and rapidly. Then, multi-resolution model for rendering is built using a modified view-dependent LOD method. Thirdly, while walking through the terrain model, the changing model is generated in real-time by adding the new visible point and deleting the invisible points locally, and also the corresponding LOD model. The procedure is iterated unless walk-through is stopped. Test of data shows the method could make nearly the real scene and gets high efficiency and accuracy of walk-through.