The Research Of The Design Of VR-GIS Based On X3D

VR-GIS have become a hot research in geographic information science domain. As the lack of unified 3D graphics standards, traditional VR-GIS have significant limitations in three aspects followed: difficult to achieve distributed data storage, sharing and inter-operating; due to self-sealing software architecture, difficult to integrate with other relative system; and because of lacking of opening, difficult to add new function. The chief purpose of this research is developing an open VR-GIS prototype system. The prototype is based on X3D the next generation of 3D graphic ISO standard, combine with other relative technologies such as data organization & inter-changing using XML, Web Services, data transmission under the network, and Xj3D.Analysis of several main VR-GIS' technical designing schemes, then pay attention to the anatomy of X3D and other relative technologies. Discuss 3D geospatial data sharing and inter-operating by using X3D standard, put forward DEM and DOM data storing-managing method adopting by pyramid classification and data split in block mode, present 3D scene modeling means based on X3D. By integrating X3D, XML, Java3D, Nonblocking Socket and HTTP-Tunnel, a four-tier distributed VR-GIS prototype has been designed. The prototype system consists of VR-GIS distributed heterogeneity data sources, universal spatial data engine, VR-GIS server layer and X3D browser layer, and it support both B/S and C/S structures. Last implement some key function.Studies show that, VR-GIS based on X3D have a great advantage than the traditional system based on other techniques such as VRML. The prototype system based on X3D can make full use of existing data resources, can be in accord with OGC data inter-operating norms, and implement data sharing and inter-operating under the environment of distributed platform and heterogeneity spatial data, and integrate with other legacy GIS systems and applications. Therefore, the prototype system based on X3D have excellent prospects in application.