Three-dimensional Building Model Sharing Technology Research Based On CityGML

With the continuous development and progress of science technology,geographical information systems(GIS)are both applied in theoretical and practical.GIS is widely used in urban modeling,decision support and decision support for emergency disasters.After the concept of "Digital Earth" was put forward,GIS played an important role in the development of 3D GIS and theoretical advancement.Given that 3D GIS can fully and accurately simulate the real world,it can be more intuitive.The three-dimensional representation of our real earth has attracted scholars' extensive attention.It is noted that computer network technology and spatial geography technical data are different because of the technical means used and the different uses of the model.There are differences in the massive,multi-source,heterogeneous and complex data exchange,storage,and visualization expressions between various 3D geometric models and topological models.The difficulty in sharing between models has inevitably led to the problem of "information isolated islands.Moreover,most of the three-dimensional models can only be used for simple visual expressions,ignoring the semantic and topological aspects of the model itself,and lacking in querying,analysis,and spatial data mining.This is not only to meet the visual sensation of people's expectations of 3D GIS.There is also a gap in the ability to analyze and query.In summary,a more general model that can meet the information needs of different application area needs to be established.In order to solve the problems of data sharing,exchange,and semantic expression between models,the Open Geospatial Consortium(OGC)proposed a modeling standard for sharing between city models: CityGML(City Geography Markup Language).,Urban Geographic Markup Language).From the point of real application of CityGML,it is necessary to solve problems of CityGML model acquisition,storage and sharing.This paper focuses on these three aspects of system research,and has a certain degree of certainty realistic guidance significance for establishing a digital,systematic,and information-sharing in three-dimensional urban information management system.This article focuses on the work of CityGML in next following areas:(1)Firstly,introduce the relationship between XML,GML,and CityGML standards.Combining the model file structure and model analysis method to study its core technology,provideing a basis for CityGML shared use and storage management.(2)Secondly,Given the short development time of the City GML standard,lacking data sources and the intricacies of building standard model data,the acquisition methods of the data model summarise the methods for obtaining 3D models,aiming at the semantics of the transformed model.Attributes,geometry,and other aspects of substandard conditions are optimized.(3)Thirdly,Based on the PostSQL/PostGIS spatial database,using the CityGML 3D model database,realizing the CityGML 3D model database construction.For the lack of standard database to expand the building model can not achieve storage management,this article based on citygml4 j open source library,development and implementation of the CityGML 3D architectural model and its extension model to import and export management tool design.(4)Compared to the traditional file format and Google Earth sharing method,the 3D geographic information network service W3 DS sharing is studied,and the GeoServer is used to publish the CityGML 3D architectural model which is stored in the spatial database,realizing the Internet-based data sharing by WFS/W3 DS standard service..