Public comment requested: OGC City Geography Markup Language (CityGML) Part 2: GML Encoding Standard

Please note:  This Request is scheduled to close on 11 November 2022.
Open Date: 
Wednesday, 2022-09-28
Closing Date: 
Friday, 2022-11-11

The Open Geospatial Consortium (OGC) seeks public comment on the OGC City Geography Markup Language (CityGML) Part 2: GML Encoding Standard. 

The CityGML 3.0 GML Encoding Standard presents the GML encoding of the concepts defined by the CityGML 3.0 Part 1: Conceptual Model (CM) Standard, which was approved as an OGC Standard in 2021. The GML encoding is compliant to GML versions 3.2 and 3.3, which is defined by ISO 19136. This encoding can be used to store and exchange 3D city models in the GML format as data sets or via web services.

Since its first publication by OGC in 2008, CityGML has been an open standard used for the storage and exchange of virtual 3D city models. CityGML allows the integration of urban geodata for use across a variety of applications, including urban and landscape planning; Urban Digital Twins for Smart Cities; the Metaverse; Building Information Modeling (BIM); mobile telecommunication; disaster management; 3D cadastre; tourism; vehicle & pedestrian navigation; autonomous driving and driving assistance; facility management; and energy, traffic, and environmental simulations.

CityGML defines a “City” in a broad fashion to comprise not just built structures, but also elevation, vegetation, water bodies, city furniture, and more. Despite its name, CityGML is useful for large areas and small regions, not just cities, and can represent the terrain and 3D objects in different Levels Of Detail simultaneously. CityGML enables the consistent representation of 3D urban objects across different Geographic Information Systems and users.

CityGML 3.0 is an evolution of the previous versions 1.0 and 2.0 of CityGML that further enables the cost-effective sustainable maintenance of 3D city models. While previous versions standardized a GML exchange format, CityGML 3.0 standardizes the underlying information model and can thus be implemented in a variety of technologies beyond GML. As a result, governments and companies can increase the Return On Investment (ROI) of their 3D city models by being able to put the same models into play across different technology platforms and application fields. 

Additional benefits of CityGML 3.0 compared to previous versions include much better integration with BIM, the ability to represent indoor spaces in different Levels of Detail (LOD), support for dynamic sensor data, and the capability to extend the information model into Application Domain Extensions using Model Driven Architecture tools.

This Part 2 of the Standard defines how the concepts developed in Part 1 are realized using XML and GML technologies. The CityGML 3.0 GML encoding represents a full mapping of the Conceptual Model and is derived fully automatically from the UML model following the UML-to-GML encoding rules as defined by ISO 19136.

A collection of example data sets for the CityGML 3.0 GML Encoding is available from the OGC CityGML-3.0 Encodings Public GitHub Repository.


Comments can be submitted to a dedicated email reflector for a thirty day period ending on the "Close request date" listed above, Comments received will be consolidated and reviewed by OGC members for incorporation into the document. Please submit your comments using the following link: requests [at] (Click here to submit comments) The link provided above should include a standard template in the message body. If the preloaded message body does not work properly using your mail client, please refer to the following template for the message body: Comments Template


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