Research And Implementation Of Accelerated Rendering Technology For Large-scale Spherical Terrain

With the "Global Information Grid" and "Digital Earth" concept proposed,to builda global multi-resolution large-scale terrain scene has become a pressing needs in theapplication areas such as virtual reality,the battlefield environment simulation,nationalsecurity, urban planning and information. However, with the rapid development ofremote sensing technology and information technology, the amount of the geographicdata has an exponential growth, and how to achieve a continuous seamless global scalemulti-resolution3D terrain model which can accommodate massive data has becomethe further research subject which must be resolved.Based on the data source of high-resolution satellite imagery and global digitalelevation model, we design and achieve a large-scale spherical terrain real-timeRoaming System. The Study bases on the acceleration of spherical terrain renderingtechnology.When it is applied to the rendering system,it can significantly improve thesystem’s real-time rendering speed. In this paper,we discusse the research status oflarge-scale spherical terrain visualization and key technology,and introduce theacceleration of terrain related drawing technology,and identify with visibility toeliminate algorithm, the global multi-resolution terrain LOD model simplificationalgorithms and spherical3d visualization of terrain as the research direction.This paper studies the global multi-resolution real-time terrain renderingalgorithm,and introduces the generating method which is based on regular hexahedronglobal discrete grid model in detail.Based on tile pieces of quadtree algorithm and thecharacteristics of the spherical terrain,we improve the quadtree algorithm, and putforward a way which is based on spherical terrain grid coding,and design a globaldiscrete grid LOD model which is based on GPU,and achieve the key technologies of aglobal multi-resolution terrain LOD model such as crack treatment, error control, andjump phenomena.This paper studies the visibility culling algorithm which is based on sphericalterrain, and improves the visibility culling algorithm which is based on flat terrain,andachieves not only the improved cone cutting algorithm and the terrain block elimination algorithm based on GPU.When it is applied to the terrain visualization system，it cansignificantly reduce the number of triangles drawn per frame and improve the efficiencyof the system to draw.This paper designes and implementes a large-scale spherical terrain visualizationsystem. Study of real-time rendering algorithms and visibility accelerated algorithm areapplied to the whole system.This article also introduces the relationship between thealgorithm’s main flow and module,and expounds the data scheduling module indetail.Based on the expand cone preloading strategy, a secondary preloading strategybased on extended cones is putted forward. In this paper,we introduce the main processof GPU rendering module and implementation details based on GPU Rendering. Alongwith the whole system function and performance test,this article finally achieves a goodinteractive and realistic large-scale spherical terrain real-time roaming system.