中文摘要：

为了进一步研究层次细节技术在实时绘制大规模地形场景中的有效应用，提高海量数据三维地形的重建速度，基于DEM数据及视觉相关地形简化的特点，提出了一种基于网格划分的实时简化算法．该方法首先将DEM栅格数据分成以视点为中心的数据块，利用视觉相关的误差简化算法实现了DEM数据的快速动态分层与地形平滑，其次利用三角剖分方法最终消除了裂缝，对实际数据的实验结果验证了本算法的有效性．该算法能有效地对地形数据进行多分辨率简化，简化后的地形不仅保留了地形表面特征，还能满足实时漫游的需求，可以高效地消除场景漫游过程中图像的跳跃。

英文摘要：

To study the effective application of level of detail （LOD） in terrain rendering at real-time frame rates and to optimize the reconstruction speed of the mass data three-dimensional terrain, a real-time LOD method based on the characteristic of the DEM data and view dependent terrain simplification is introduced in this paper. Firstly, the method divided the terrain into a set of nested regular grids centered on viewers, and realized the dynamic delimitation and terrain smoothing of DEM data using the view dependent terrain simplified algorithm. Secondly, the crack was eliminated by the triangle division method and the effectiveness of the algorithm was demonstrated by the results of experiment on practical data. This algorithm can carry out multi-resolution simplification on terrain data effectively, the terrain simplified can not only retain the surface character of the terrain, but also satisfy the demand of real-time roaming, and eliminate image caper during the scene roaming process.