Research On Management Of 3DGIS Data And Presentation Of 3D Symbol

As the inevitable result of the 2D GIS that develops to a certain technical stage, the 3D GIS can directly reflect many kinds of relative information of geographical area, such as terrain, relief, ground feature and so on. At present, many scholars bring forward some methods and technical means to the data model, visual representation and applications in a single field of 3D GIS. But the research and implementation of 3D GIS are still in the primary stage. Some parts of 3D GIS functions implemented only in experimental prototype systems. The research in this dissertation mainly includes following several aspects:(1)It describes the basic concept of 3D GIS and brings forward the essence of 3D GIS, namely, the space coordinate of 3D object is represented by (X, Y, Z). It discusses the aim and significance of the research on 3D GIS, and describes the relations among the 3D GIS, VR and simulation. This dissertation also introduces the mainstream 3D visualization software home and abroad, and analyzes the research status quo and basic requirements of 3D GIS. Issues in the present research and implementation are summarized and the thought to the development of 3D GIS is brought forward.(2) The research result on 3D data model of 3D entity representation is introduced, and The concept of the organization form of 3D entity if brought forward, namely 3D Shape Entity (SE). It considers that the basic selection foundation of 3D GIS spatial entity data model is the data organization mode base on surface. The data structure of 3D SE is mainly Surface Representation method and the data of SE is embedded into the GIS vector structure. Base on the characteristics and classification of spatial data model, the data contents and database management mode of 3D GIS is summarized, and the classification of 3D spatial object, which is the basis element of 3D GIS is brought forward and described.(3)It brings forward the 3D spatial vector data model based on Surface Representation (SR3D). This kind of 3D vector data model develops from the object-oriented 2D GIS and accords with the custom of processing the GIS element. So it is easy to implement the transition from 2D to 3D. In the practice of 3D GIS prototype system, the 3D vector data structure and 3D SE data structure are designed and realized. The data structures not only can guarantee the correlation between the ground feature data and terrain data but also can be applied alone to support the mass data roam of large region on PC.(4)It introduces the organization mode of mass data and describes the multi-task subsequent process technique based on thread and the data management technique based on dynamic load of data page. It also presents the time index of data management in the mass data demonstration. The organization principle and way of the 3D spatial object data and is studied, and the management assumption to organize the 3D vector data in the form of different layer with different LoD Grades is brought forward.