介绍了多分辨率分形地景生成方法,以及地景的不同区域具有不同细节层次特点的研究成果.其基本思想是以视点在水平面的投影为参考起点,来生成一个很小的原始数据集,进一步构成多分辨率三角形网格,用以确定地形基座的形状.并用分形技术中的中点位移法及三角形边线细分方案对地形进行递归细分,从而生成自然的地形景观.其多分辨率基座的构造方法在不需要额外开销的情况下,解决了不同细节层次区域间的空间连续性和时间连续性的问题,从而避免了空洞、缝隙的出现.此外,基座可以根据具体情况扩展成所需要的形状,因而具有较强的可扩展性.实验结果说明,该方法是一种简单快速、适于实时显示的地形景观生成方法.

The real-time terrain generation techniques based on Digital Terrain Model (DTM) have a high requirement to hardware. And in many practical applications there is no need to simulate the terrain of certain area. Also people want to generate various terrain with different shape characters in order to meet different requirements flexibly. At this time it is obviously uneconomical to still use the method based on DTM. For this reason, the paper studies the modeling approach to 3D fractal terrain using data as little as possible for the PC. The terrain belongs to the multiresolution model that has several levels of detail coexisting. The projection of viewpoint is regarded as reference point from which a small primitive data set is generated, and forms multiresolution triangle meshes which define the shape of terrain base. Then, iteration is done by midpoint displacement and triangle edge sub-division method. It can produce natural terrains with different shapes. The construction method of multiresolution base has solved“spatial continuity”and“temporal continuity”between areas with different level of detail and avoids holes and seams, at the same time it dose not need extra computing works. Additionally, the base has a expansibility and can be expanded to needed shapes. The experimental results show that the method is simple, rapid and suitable for real-time display.