Study On Building City Models Using CityGML

’:In recent years, as the proposal of digital earth, digital city, simple2D GIS technology could not meet the demand for large-scale three-dimensional continuous spatial data processing. But with the development of technology, pace of urbanization in the whole world is faster and faster. Duplication of data, as well as the fact that traditional GIS does not care much about semantics and topology, makes it difficult to realize digital city and to build a large scale3D city application. Considering it, OGC proposed3D City Common Information Model——City Geography Markup Language CityGML. Common Information Model enabled sharing of data between different companies and organizations, and solved the problem of excessive data redundancy caused by inconsistent data formats. CityGML classified most of the city objects, considering their geometry features, as well as the topological relations between each other.Considering CityGML developing situation in our country, it is difficult to build3D city model totally with CityGML in a short time, but it is definitely an important studying direction. Bridge plays a really important role in modern transportation. As the industrility speed getting faster, transportation tasks become more and more, so that bridge gets more and more pressure. It is a really important issue to monitor the bridge health situation so as to reduce happening of accidents. According to this, this article will focus on making CityGML model for single bridge, through modeling a bridge model in CityGML prove the possibility of using CityGML in3D city modeling, to reduce data redandency and inprove topo relation description. It could provide some reference for large scale CityGML modeling for3D city.In this article, firstly the development background and the current reseach status of both here and abroad are introduced briefly. Secondly the CityGML basic technology XML and GML are in detailed introduction, including the XML syntax rules, the main component of GML, how to build GML application schemas and so on. Then CityGML related technologies, including CityGML core technology five level of detail, CityGML module, closure surface, etc. are listed. Thirdly, a bridge model is taken as an example, showing how to obtain data for building the CityGML model, to make dwg file with AutoCAD, to transform dwg into CityGML file, trying to visualize it and use it for special field including bridge health monitoring, Last part is the summary and outlook of CityGML...