| The 3D GIS has gradually entered into people's production and life with the rapid development of computer technology,virtual reality technology,GIS technology and the urgent need of human for geographic information service.The most representative are the visualization technology and spatial query technology of 3D GIS,it is also very important in geosciences research,pipeline network visualization,highway system and so on.However,the function of GIS can not only stay in 3D visualization stage.To develop a complete GIS system should include the following features,such as spatial information visualization,spatial query and spatial analysis.On the other hand,the real 3D operating system in some fields can only be run on a local stand-alone machine and can not realize the distributed data sharing and interaction based on the network environment.The paper establishes a real 3D spatial database based on the spatial location information and attribute information of the spatial entities.Realize the spatial query and attribute query based on the true 3D data under the network environment.In this paper,the offices of School of Geodesy and Geomatics are the smallest spatial research objects.Using JavaScript technology,spatial database technology and VRML technology,a real three-dimensional entity publishing platform is established under the distributed structure.And the establishment of the entity model and the realization of the spatial and attribute query functions are accomplished through the following steps.1.Collect two-dimensional coordinates from the electronic map of AUST,combine the coordinates with the storey height as the spatial coordinates data,and then pre-process the data.2.To establish a spatial database,including the spatial coordinates data,the topological relation data and the attribute information.Through the JavaScript language and EAI interface to complete the spatial data to the VRML scene transfer.3.Through the JavaScript technology and EAI interface accomplish the realization on VRML browser embedded in HTML pages.The last but not least,through the programmed algorithm achieve the interaction with the model.Draw and display 3D models through VRML browser embedded in HTML pages.Finally,spatial query and attribute query based on true 3D spatial data are realized based on the algorithm of minimum bounding box,SQL combined with JavaScript technology,VRML technology and ASP.net technology.This article provides a way to establish a dynamic model in the network environment and realize spatial query and attribute query of three-dimensional entities.And it provides a technical path for the realization of the functions of spatial analysis and decision-making of 3D GIS.It also laid a good foundation for the future research of Web 3DGIS technology. |
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