An Improved Simplification Algorithm of 3d Terrain Visualization Model

Digital Elevation Model (DEM) is a kind of method and means describing three-dimension terrain visualization in computer graphics and visualization. However, there are plenty of redundant data in DEM that is described by grid or TIN (triangulated Irregular Network). The main content of this paper is the study about 3D surface simplification in terrain visualization model based on triangulated network (both irregular and regular). There are many algorithms and methods in 3D model simplification. Our algorithm adopts the method of iterative edge contraction. Firstly, every edge in DEM is assigned a cost, namely the error resulting from its contraction, and the error is accumulated error, not isolated error. When a edge is contracted, its cost (i.e. the error) will be transferred to the neighborhood. According to this idea we can control the whole error resulting from the model simplification in DEM freely and conveniently. Secondly, track the lowest-cost edge and contract it. The result of this contraction is reducing one point, three edges and two faces. Thirdly, reorganize the cost of correlated edge affected by contraction. Finally, iterate this contraction till some criteria is achieved.