The Open Geospatial Consortium (OGC®) seeks public comment on Version 1.1 of the OGC City Geography Markup Language (CityGML) Encoding Standard (http://www.opengeospatial.org/standards/citygml).

CityGML is an open information model and XML-based encoding for the representation, storage, and exchange of virtual 3D city models. It provides a way to describe objects with respect to their geometry, topology, semantics and appearance, and it defines five different levels of detail. CityGML allows users to employ virtual 3D city models for sophisticated analysis and display tasks in different application domains such as pedestrian navigation, environmental simulations, urban data mining, facilities management, real estate appraisal, and location based marketing.

CityGML has been implemented in many software solutions and is in use in many projects around the world. Developed for Urban Information Modeling applications, CityGML plays an important role in bridging Urban Information Models with Building Information Models (BIM) to improve interoperability among the information systems used in the many areas of activity that involve design, construction, ownership and operation of buildings and capital projects.

CityGML is implemented as an application schema of the OGC Geography Markup Language 3 (GML3) Encoding Standard (http://www.opengeospatial.org/standards/gml), an international standard for spatial data exchange and encoding approved by the OGC and the International Organization for Standardization (ISO).

The current version 1.0 of CityGML was adopted as an official OGC Standard in August 2008 and has come to wide use since then. The OGC Technical Committee's CityGML Working Group has received input from the wider community in the form of change requests, proposed additions and suggestions. With this guidance, the Working Group developed the draft CityGML Version 1.1, a minor revision of the current CityGML version 1.0 that maintains backwards compatibility with version 1.0.

Version 1.1 includes new thematic modules for tunnels and bridges, the ability to model footprint and roof edge representations for buildings in the coarsest level of detail, and generic attribute sets, as well as a number of additional properties and other enhancements.

The candidate CityGML Version 1.1 standard documents are available for review and comment at http://www.opengeospatial.org/standards/requests/82. Comments are due by 14 September 2011.

The OGC is an international consortium of more than 415 companies, government agencies, research organizations, and universities participating in a consensus process to develop publicly available geospatial standards. OGC Standards support interoperable solutions that "geo-enable" the Web, wireless and location-based services, and mainstream IT. OGC Standards empower technology developers to make geospatial information and services accessible and useful with any application that needs to be geospatially enabled. Visit the OGC website at http://www.opengeospatial.org.