中文摘要：

针对大规模地形难以一次性导入内存建模，提出了适用于内外存调度的上层四叉树下层二又树的双层结构。通过对三角形二叉树剖分算法的改进，避免了双层地形之间的裂缝问题；对上层四又树，通过构建饱和四又树包围球判断可见性，减少了三角形冗余；使用循环二维数组结构存储数据缓冲区和视点关注区数据，实现对预加载数据的实时调度，提高了地形绘制的速度。实验表明该方法在大规模地形中，实现了视点漫游场景时平滑无缝地过渡。

英文摘要：

In order to resolve the problem that the large scale terrain is difficult to transport to main memory modeling in a lump, a double-layers frame with up-quadtree sub-binary tree was brought forward. Data was dispatched between the main memory and the bulk memory compatibly. With improving the decomposition algorithm of the triangle binary tree, the crack problem between the double-layer terrains was avoided, To judge the visibility, saturated quadtree ball was applied to reduce the triangle redundancy. The circular planar array was designed to store the buffer data and the data in view-frustum center. The real-time paging of preload data was realized, and the rendering was speeded up. The experimental results show that, when viewpoint roaming about on the large scale terrain, scene is transited smoothly without cracks.