A Research On The Technology Of Global Multi-resolution Terrain Environment Simulation

The Real-time Visualization Technology of Large Terrain is playing a key role in many applications such as 3DGIS, simulation system, visual reality and 3D games, etc. With the rapid development of the remote sense, satellite technology and computer technology, people expect to investigate or view global multi-resolution three dimension terrain regions with finer precision, which inevitably makes the real-time rendering of huge terrain become more difficult. By using the Global Digital Elevation Model and high resolution satellite image as data resources, this paper focuses on the technology of global multi-resolution terrain environment simulation, and improves the rendering speed of massive terrain data by the new rending algorithm. The main contents and contributions in this thesis can be summarized as follows:1. A efficiency model for organization and management of global massive terrain data is constructed. On the base of this model we make delamination and tiling. The paper expounds the method and structure of transverse block and analyse the feasibility of this scheme by experiment, also tells us the creation mechanism and key technology on the conversion and pretreatment of global multi-resolution dem and texture, and realizes a data engine which supports the file system.2. We modify the Geometry Clipmap algorithm to render massive terrain environment, which eliminates the border cracks successfully. Four accelerated methods are proved by experimental data, which include using triangle strip, frustum culling, making display list and gradually renewing data. These methods are used to improve the rending efficiency. Using how many Lod levels is made contrasted test, at last a rational idea is put forward which makes a great balance between rending speed and effect.3. A algorithm on how to compute sphere-based view field is put forward, which promotes the global multi-resolution block algorithm. We find a solution to this problem, demonstrating its feasibility experimentally. Linearity interpolation algorithm is used to make automatically moving in the global three dimension terrain environment.4. By intergrating the terrain data engine and rendering engine, we design and implement "the Global Multi-resolution Terrain Simulation System" with the help of modularization, which can realize the 3D real-time rendering via multi- resolution terrain data of the global area. The system is used widely in the field of digital earth, 3D GIS and the visualization of battlefield environment. In the end, frame system, structure designing, hardware environment and experimental data about the system are introduced; we show some picture about the system.