CityGML is an open standardised

data model A data model is an abstract model that organizes elements of data and standardizes how they relate to one another and to the properties of real-world entities. For instance, a data model may specify that the data element representing a car be co ...

and exchange format to store digital 3D models of cities and

landscapes A landscape is the visible features of an area of Terrestrial ecoregion, land, its landforms, and how they integrate with Nature, natural or man-made features, often considered in terms of their aesthetic appeal.''New Oxford American Dictionar ...

. It defines ways to describe most of the common 3D features and objects found in cities (such as buildings, roads, rivers, bridges, vegetation and city furniture) and the relationships between them. It also defines different standard levels of detail (LoDs) for the 3D objects, which allows the representation of objects for different applications and purposes, such as simulations, urban data mining, facility management, and thematic inquiries. CityGML is implemented as a GML application schema for the

Geography Markup Language The Geography Markup Language (GML) is the XML grammar defined by the Open Geospatial Consortium (OGC) to express geographical features. GML serves as a modeling language for geographic systems as well as an open interchange format for geographic ...

3 (GML3), the extendible international standard for spatial data exchange issued by the

Open Geospatial Consortium The Open Geospatial Consortium (OGC), an international voluntary consensus standards organization for geospatial content and location-based services, sensor web and Internet of Things, GIS data processing and data sharing. It originated in 1994 ...

(OGC) and the ISO TC211.

Implementations

In its most common implementation, which is the one generally used to disseminate and exchange data, CityGML datasets consist of a set of

XML Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing arbitrary data. It defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. T ...

files and possibly some accompanying image files that are used as textures. Each text file can represent a part of the dataset, such as a specific region, a specific type of object (such as a set of roads), or a predefined LoD. The structure of a CityGML file is a hierarchy that ultimately reaches down to individual objects and their attributes. These objects have a geometry that is described using GML. Another important implementation of CityGML is the one of 3D City DB, which stores CityGML in a database.

Version history

The OGC Members adopted version 1.0.0 of CityGML as an official OGC Standard in August 2008. In late 2011, the OGC Members approved version CityGML 2.0.0. CityGML 3.0 ''GML Encoding Specification'' is supposed to be published early 2019, while CityGML 3.0 ''Conceptual Model'' draft is already publicly available at th
official Github repository

References

{{reflist

External links

CityGML standard page from the Open Geospatial Consortium

Official CityGML site

CityGML Wiki
* Free Viewers/Tools for CityGML: *
azul
*
Aristoteles
*
FZKViewer
* Commercial Viewers/Tools for CityGML: *
CityEditor (SketchUp Plugin)
GIS vector file formats XML-based standards Vector graphics markup languages

Implementations

Version history

See also

References

External links