A HYBRID LOD ALGORITHM BASED ON TIN MODELLING

摘要

Triangulated Irregular Network (TIN) is a high-effect means expressing the terrain surface in the computer, compared with GRID model, TIN model can use less sampling to approach the terrain surface precisely, this is why we study Visualization of TIN model. The data structure of TIN model is complex, therefore to realize View-dependence LOD representation of TIN is difficult. General method is to partition the TIN, every tile adopt the different resolution according to the distance from viewpoint.Quadtree domain decomposition is adopted on TIN in this paper, and this is no longer simple rectangular partition to realize View-dependence LOD representation of TIN, but Through building a quadtree structure for tiling of TIN, and combining quadtree based LOD methods to realize controlling over the tiling of TIN effectively, this method can combines adjoining tile sometimes, the high limit cuts down the triangle quantity in the LOD mesh. This algorithm has combined TIN and quadtree structure, and combines quadtree based LOD methods and TIN based triangle mesh simplification methods to realize the view-dependence lever-of-detail controlling over the TIN model. Research indicates that this algorithm cuts down the triangle quantity in the LOD mesh and doesn't lose visual effect, a lever-of-detail mesh, similar with Grid and the TIN hybrid structure, has been acquired.