Design And Implementation Of The Terrain And Vector Data Rendering System In3DGIS Based On OSG

At present, it is an important characteristic of3D GIS that terrain data volume isenormous. And, when roaming local high resolution terrain, the number of polygonsvertex can be as large as one million, which can’t be all rendered by ordinarycomputer hardware. The traditional2D vector data model is a kind of important datamodel and data sources of GIS. With the development of information technology,people require it perfect match geographical spatial vector data and the terrain, andplay advantages of the terrain and the GIS vector data. To achieve this goal, the firstissue to be solved is how to organize, manage and real-time render spatial data.Thispaper overcome it by using OSG as scene management tools, the emphases of theresearch as followings:(1) The study of the important data sources of digital terrain construction: DigitalTerrain Model. This thesis explore the concept, data structure and characteristics ofthe recent three main types of DEM, and select regular grid DEM as one source ofdata for this study according the purposes of the study at last. Then, the paperdiscusses OSG’s related project of3D terrain in the way of organization: the level ofdetails model, the file storage method of pyramid model and the multi-level mappingtechnology of remote sensing image texture. In the end, the paper discusses OSG’sdynamic scheduling mechanism of model data.(2) This thesis studies the2D GIS vector data fileformat, which for seeking theentry point of OSG scene model conversion deeply. This thesis analyzes the technicalline of the rendering combined vector data with terrain, and then decompose theprocess of converting Vector data to OSG scene model with detailing each link of the task.(3) In order to research the ability of real-time rendering of the terrain and vectordata, the paper developed a small3DGIS rendering system on the basis of OSG.Firstly, this thesis designs the architecture of this system, analyze the function moduleand give the software framework. Secondly, This thesis analyzes theimplementmethod of different function modules. Finally, this thesis studies themultithreading mechanisms on the vector data processing and operation scene in thissystem.(4) At last, the paper made a comparative analysis on combined renderingperformance of the terrain and vector data. The result shows it can realize thereal-time rendering of large amount of terrain data and vector on the basis of thesolution of that is based on OSG.