一种渐进格网模型的改进算法

多分辨率的动态简化是一种提高地形三维显示速度的重要方法．研究了适用于道路与地形集成模型的多分辨率动态简化方法，分析了渐进格网模型应用于地形集成模型的简化时所存在的一些问题，并根据集成模型的特点。提出了一种改进的算法，与其他方法不同的是：1）此模型采用一种“回”结构的分辨率划分方法，与模型的几何形状无关，较好地实现了道路与地形集成模型的动态简化；2）通过控制顶点树的深度，解决了模型简化后难以恢复的问题，同时避免了在模型简化过程中出现交叉、重叠和细长的三角形．结果表明：该算法能更好地适用于道路与地形集成模型的多分辨率动态简化，并具有较高的速度．

A Improved Progressive Mesh Algorithm

Dynamic simplification with multi-resolution is an important method to improve the speed of terrain rendering.A dynamic multi-resolution simplification model fitting to terrain model integrating road network was discussed.We analyzed the progressive mesh(PM) firstly,and pointed out some limitations when PM is used for to terrain model integrating with road network.Based on the feature of integrated model,a new level of detail model was proposed.Compared with the previous approaches,using the algorithm the integrated terrain can be divided into multiple levels resolutions in the shape of 'dip' regardless of the geometrical shape of meshes,and is capable of dynamically simplifying terrain models with road network embedded.Moreover,the algorithm can efficiently solve the difficulty of mesh recovery and overcome triangles with a thin and long shape during the model simplification by constraining the depth of vertex.The results show that the proposed method can perform simplification better and faster than the previous methods for terrain models with road network embedded.