Research Of Multilevel Dynamic Complex Terrain Rendering Key Algorithm

Virtual reality technology is a very popular frontier subject and research direction in the world at present.It is widely used in many related fields.Such as games,medical,military and other aspects.Virtual reality technology includes environment simulation,perception,natural skills and sensing equipment.This paper studies the environment simulation in virtual reality.The environment simulation mainly studies the 3D image rendered by computer,especially the large-scale complex terrain rendering,which involves a rendering efficiency problem.At present LOD(Level Of Detail)model is a kind of graphics technology which is often used to speed up the efficiency of graphics rendering in 3D rendering of large scale terrain.The main idea is to divide the terrain data into diffenrent levels,and to speed up the rendering speed under the premise of keeping the whole landform characteristic.Especially,the simulation of complex scene is more effective.But in the rendering of different precision of the drawing area,there will be points which aren't belong to both sides in the same time between the two blocks,that will cause into cracks,which will affect the rendering results.The main works are as follow:Firstly,study the existing large-scale complex terrain rendering methods,including the hierarchical division of the terrain,the judgment of visibility,the calculation of error metrics.Discuss the advantages and disadvantages of the existing technology.Secondly,in the LOD algorithm data storage mode,crack repair and other aspects of research,put forward the improved method:1)In the data storage mode,according to several models of LOD algorithm,aiming at quadtree and the binarytree model and other mainstream construction technology,research the implementation of tree structure.Based on the research of the traditional LOD quadtree terrain generation algorithm,the improved construction method of the quadtree is proposed in this paper.The improved method optimizes the storage structure of the node,and simplifies the storage information of each node.2)In the production and repair of cracks,this paper studied the causes and some existing methods to eliminate cracks.Combined with the optimized node storage structure,this paper proposes to find the adjacent nodes by addressing parent nodes to effectively eliminate the cracks.3)In the judgment of hierarchy division,a method of constructing four points bounding sphere is proposed to determine the range of a terrain block,and a LOD optimization algorithm based on normal vector and visual angle is proposed.The algorithm displays the hierarchy by control the threshold,and constructs the bounding ball by four points of the terrain block data structure,and then the terrain block in the visual region is drawn with the clipping of the window to improve the rendering efficiency.Finally,this paper use the complex terrain rendering as an example,make the quadtree hierarchical processing of the original grid data,through the error evaluation factor,to achieve LOD terrain rendering.And use C# and SharpGL to achieve the algorithm,through the elevation map of the three-dimensional layered rendering to verify the advantages of this algorithm in terrain rendering.