Research On Large Scale Terrain Generation Technology Based On OSG

With the development of the society, the application demands based on 3D terrain visualization technology emerge in endlessly. Geographic information system, games entertainment, flight environment simulation, and many other areas, are in need of realistic 3D terrain scene. In recent years, with the rapid development of satellite and remote sensing technology, the resolution of terrain data is higher and higher, and the amount of data is far beyond the processing capacity of the current computer hardware device. How to render large scale 3D terrain scene in real-time becomes a hotspot in the related fields.Reducing the amount of real-time rendering is an effective way to achieve the real-time rendering of large-scale terrain scene in the limited processing capacity of computer graphics device. In order to achieve this goal, the key is to simplify the rendering terrain model and realizes the dynamic scheduling of terrain data. On the basis of open-source 3D rendering engine(OpenSceneGraph, OSG), this paper finds some ways to realize the generation of large-scale terrain, by means of the organization and management mechanism of terrain data, the simplification of terrain model and the dynamic scheduling algorithm. Besides, on the basis of the existing algorithm, this thesis explores some new methods and techniques to achieve the goal. The main research contents are as follows:1. The research of block processing. Based on the research and analysis of the existing partition processing method, this paper adopts a regular block model with the same size and divides the original terrain data into equal pieces, stored in the local disk.2. The design of organization and management mechanism of terrain data. This paper adopts the pyramid model to manage the generated multiresolution LOD(Levels of Detail) model and use the quad-tree structure to organize these multiresolution model, so that these models can be quickly find in the process of dynamic scheduling.3. The research of dynamic scheduling algorithm. This paper studies the dynamic scheduling algorithm of three-dimensional scene, including visibility calculation, terrain model simplification, fracture removing. Based on the study of these technologies, this paper put forward the improved ideas of quad-tree segmentation algorithm and terrain forecasting algorithm.4. The design and implementation of prototype system. Based on the key techniques researched above, the overall framework and function module design are given. After that, this thesis implements the entire function module, including terrain database generation module, 3D terrain scene shows module and roaming module.After the testing, all the function modules of the prototype system are achieved the desired goal and meet the function demand of large scale terrain generation. At the same time, in terms of performance testing, the algorithm adopted in this paper can achieve high frame rate in the generated results. So it can smoothly display the three-dimensional scene and realize real-time interaction. The key technology in this thesis has certain advantage.