Terrain Simplification And Roaming Based On The Tree Structure

3D terrain visualization is always a hot topic in Geographic Information System (GIS), Virtual Reality (VR), simulation of battlefield environment and other associated fields. The method of terrain simplification becomes one of the best important contents in 3D terrain visualization. Although the performance of computer hardware has a rapid development now, data capacity is also increasing fleetly and continuously with the improvement of collection precision of height and texture data. Therefore, it is necessary and important to do a research on the storage, real-time loading, simplification and roaming technology.For the embedded research of the technology of terrain data simplification, this paper is divided into three parts. At first, as the data structure of DEM is discussed, a method of terrain storage, forecast load and real-time load is given based on wavelet transform which has a multi-scale feature. Secondly, two kinds of multiresolution LOD structure, which are binary tree and quad tree, are deeply discussed. For ROAM algorithm based on binary tree, a new formula about node error, which also considers the direction of line of sight, is proposed; and a promoted drawing mode based on triangle strips is presented, which improves frame velocity during drawing time. For the quad tree model, a new function of node complex measure called local energy is presented, which is computed simply and expresses terrain veritably; then, a simple and novel roaming algorithm based on triangle quad tree is given. At last, this paper does a primary research on OpenGL rendering technology, and finally a real-time roaming system of terrain based on improved simplification model of binary tree and quad tree is realized in Visual C++ platform by using OpenGL technology.