Multi-resolution visualized model of the global terrain based on DQG

摘要

Real-time and realistic visualization of the Earth terrain based on Global Discrete Grids is a subject of considerable attention at present. In this paper a multi-resolution visualized model of the global terrain based on DQG (Degenerate Quadtree Grid) is approached. Our approach starts with a partition method, called Degenerate Quadtree Grid (DQG) and an encoding scheme of the corresponding grids is introduced briefly. Next, a multiple level of detailed model related to viewpoint is presented. In this model, a criterion of terrain model simplification based on viewpoint and roughness of the degenerate quadtree node is developed. Then, the quick display strategy based on DQG is discussed. It includes two parts: one is frustum culling while the other is dynamic invocation of the data. In the end, the experiment and analysis are made with the global terrain data, GTOPO30. The results illustrate that: (1) the global DEM based on the DQG is seamless, hierarchical, and regular over the whole Earth; (2) the quantity of global DEM data can be reduced significantly; (3) the visual effect of global terrain is not lost by the model simplification. The results are smooth and receivable.