The Research To Massive Spherical Terrain Visualizing Methods Based On GPU

Global multi-resolution digital earth model that based on massive terrain data has become one of the most popular current research topic, which has been widely applied in many fields, such as GIS, aviation simulation, location detection, virtual battlefield situation, medical images, 3D online games and other fields. The key to be achieved by the visualization system in this thesis is the design and implement of reasonable and efficient scheduling terrain data organization, as well as real-time rendering of terrain.In the process of implementation of visualization system, the main research work includes:(1) Implementation of the terrain data organization scheduling: organizing the terrain data blocks hierarchically based on the construction technology using latitude and longitude with equal intervals and LOD technology; Scheduling the terrain elevation and texture data by multi-thread parallel mechanism.(2) Implementation of large-scale spherical terrain using real-time rendering techniques: adopting the real-time rendering algorithm based on quad-tree tile to construct the terrain quad-tree grid, and updating the terrain mesh node according to the viewing frustum, the texture projection area of a terrain block and the elevation projection error of a terrain block.(3) Improving the rendering efficiency by LOD technology based on quad-tree and culling techniques;(4) Implementation of the sky, light, ocean and terrain’s shading effects.In this thesis, Blue Marble Next Generation is selected as raw data of the visualization system. Then these terrain elevation data and texture data are separated hierarchically to generate terrain data blocks with different resolutions and unique LodID, and the data scheduling module will create two sub-threads to schedule the data.The terrain is modeled by quad-tree tiled block real-time rendering algorithm in this thesis, then it generates 50 quad-trees and each quad-tree node represents a different terrain block which is identified by an unique LodID. This thesis also proposes the solutions of terrain crack and jumping problems caused by the changing of controllable camera viewpoint. In order to enhance realism of the visualization system, this thesis implements the sky, ocean, light and other simulation results; and at last, this thesis usesthe GPU to realize the terrain in order to improve rendering efficiency.