Research On Samantic Query And Sharing Of3D City Model Based On CityGML

In the process of social development, Geographic Information System (GIS),playing an increasingly important role, is widely employed in fields of urbanplanning, disaster prediction, traffic management, etc. Although the2D GIS has arelatively mature development, it always cannot be used to accurately reappeargeographical objects in the real world. Therefore, people turn their study eyes to the3D GIS which has more direct-viewing visual effects and much richer performancecontents. One of the most popular research directions is3D city models. Largecommercial companies have established the3D city models under their respectiveplatforms. At the very first, the models only pursue the accurate reappearance ofgeometrical shapes rather than the expression of inherent semantic properties andtopological structure of the models. Due to the lack of a unified modeling standard,the versatility and sharing of3D city models all around the world are greatlyaffected. In response to these issues, Open Geospatial Consortium (OGC) releasesthe standard of3D city modeling—CityGML (City Geography Markup Language).CityGML, based on GML (Geography Markup Language) and using XML(Extensible Markup Language) as the data storage format, provides a unified codingstandard for3D city modeling. Compared with other modeling languages, CityGML,paying closer attention to model expressions in the level of semantic properties,meets the people’s demands of understanding and applying the internal structure andintrinsic properties of geographic objects. Based on common modeling standards,CityGML also provides a guarantee for the realization of the sharing of3D modelsall around the world.Since the release of the CityGML in August2008, research at home and abroadbased on CityGML has relatively concentrated on the large-scale3D city modelingwith the common standard of CityGML, as well as the transformation of the originalmodels into CityGML models. Problems such as the application of model sharingmechanism as well as inquiry and analysis of properties of the3D models which have been built up are research emphases of CityGML. However, the number of thedomestic researches aiming at the above problems is little, let alone relative data.The main work of the paper is as follow:○1in order to query the semanticproperties of CityGML models, this paper arranges the mapping methods of thecorresponding data sheets of different classes—the core module, the appearancemodule, geometrical patterns of models—in CityGML space database, analyzessemantic representation of the3D buildings based on CityGML, discusses thetechnical problems which are needed to be solved to set up3D spatial databasebased on CityGML;○2Setting up the CityGML spacial database with a graphicaluser interface by using the3D CityDB Importer/Exporter tool, and convenientlycarries out the import and outport of the CityGML file;○3Querying the semanticproperties of the building data in CityGML spacial database and providing a fast andeffective method to visualize the query results;○4Outputting the CityGML modeldata in KML data format, this database, combining with the visualization technologyof Google Earth, proposes a method of sharing CityGML in the environment ofInternet, and puts it into practice to make a validation.