CityGML - City Geography Markup Language
The City Geography Markup Language (CityGML) is a new and innovative concept for the modelling and exchange of 3D city and landscape models that is quickly being adopted on an international level. CityGML is a common information model for the representation of 3D urban objects. It defines the classes and relations for the most relevant topographic objects in cities and regional models with respect to their geometrical, topological, semantical and appearance properties. Included are generalization hierarchies between thematic classes, aggregations, relations between objects, and spatial properties. In contrast to other 3D vector formats, CityGML is based on a rich, general purpose information model in addition to geometry and graphics content that allows to employ virtual 3D city models for sophisticated analysis tasks in different application domains like simulations, urban data mining, facility management, and thematic inquiries. Targeted application areas explicitly include urban and landscape planning; architectural design; tourist and leisure activities; 3D cadastres; environmental simulations; mobile telecommunications; disaster management; homeland security; vehicle and pedestrian navigation; training simulators; and mobile robotics.
CityGML is realised as an open data model and XML-based format for the storage and exchange of virtual 3D city models. It is implemented as an application schema for the Geography Markup Language version 3.1.1 (GML3), the extendible international standard for spatial data exchange issued by the Open Geospatial Consortium (OGC) and the ISO TC211. CityGML is intended to become an open standard and therefore can be used free of charge.
The CityGMLWiki is an open portal to publish and share information about CityGML. However, it is not the offical website of the CityGML. Please find the official website of CityGML at http://www.citygml.org.
The OGC Technical Committee has approved the CityGML Specification version 0.4.0 as an OGC Best Practices Paper at its meeting in Paris. Therefore, CityGML is an official position of the OGC membership on 3D city modelling. The Specification document (OGC Document No. 07-062, PDF 9.8MB) can be freely downloaded from the Best Practices Paper section of the Open Geospatial Consortium website. Within OGC, CityGML is discussed and further developed within the 3D Information Management (3DIM) Working Group (formerly CAD/GIS Interoperability Working Group).
A Change Document tracking the changes from the previous CityGML version 0.3.0 (OGC Document No. 06-057r1, PDF 3.1MB) to CityGML version 0.4.0 can be obtained here (PDF 4MB). Please note, that this document is not an official part of the CityGML Specification. It is only intended to give an informative and informal overview of the significant changes and to reflect the discussions on received change proposals and comments.
- CityGML Homepage: http://www.citygml.org (includes test datasets and software tools)
- Open Geospatial Consortium (OGC): http://www.opengeospatial.org
- OGC 3DIM Working Group: http://www.opengeospatial.org/projects/groups/3dimwg
- SIG 3D - NRW Homepage (in German only): http://www.ikg.uni-bonn.de/sig3d
IFC - Industry Foundation Classes
The IFC (Industry Foundation Classes) specification is a neutral data model to describe, exchange and share information typically used within the building and facility management industry sector. More Information can be found in the IFC Wiki.