ISO 19136

ISO 19136. It is an international standard from the International Organization for Standardization (ISO) that defines the Geography Markup Language (GML), an Extensible Markup Language (XML) grammar for expressing geographical features. This standard provides a framework for modeling, transporting, and storing geospatial information, enabling interoperability between diverse geographic information system (GIS) applications. Developed and maintained by ISO/TC 211, it is a foundational component within the broader suite of ISO 19100 series standards for geographic information.

Overview

The standard specifies the syntax and mechanisms for defining geographic features, coverages, observations, topology, and value objects using the Extensible Markup Language (XML) schema language. It enables the encoding of complex spatial data, such as points, lines, and polygons, as well as their non-spatial attributes, for use in web services and data exchange. By providing a common modeling language, it supports the creation of interoperable geospatial data across different systems and organizations, such as those used by the Open Geospatial Consortium (OGC) in its Web Feature Service (WFS). The core conceptual model is aligned with the general feature model defined in ISO 19109.

History and development

The development of GML began within the Open Geospatial Consortium in the late 1990s, with version 1.0 released in 2000. Recognizing its potential for standardization, the work was brought under the purview of ISO/TC 211, the technical committee responsible for geographic information standards. The first edition of the standard was published in 2007, formally establishing GML as an International Organization for Standardization (ISO) standard. Subsequent amendments and a second edition (ISO 19136:2007/Amd 1:2011) have been released to extend its capabilities, incorporating developments from the broader geospatial community and evolving web technology practices.

Technical specifications

The technical foundation is an XML Schema (XSD) application profile, defining a set of XML encoding rules for concepts established in other ISO 19100 series standards. It includes core schemas for basic geometry types (aligned with ISO 19107), temporal objects, units of measure, and coordinate reference systems (as defined in ISO 19111). A key feature is its extensibility, allowing users to create application schemas for specialized domains, such as cadastre, transportation, or hydrography. The standard also specifies support for GMLJP2, enabling the embedding of GML data within JPEG 2000 imagery files.

Relationship to other standards

It is deeply integrated within the ecosystem of ISO/TC 211 standards. It directly implements the spatial schema from ISO 19107 and the rules for application schemas from ISO 19109. Its encoding of coordinate reference systems relies on definitions from ISO 19111. Furthermore, it is a critical dependency for other implementation standards, such as ISO 19142 (Web Feature Service) and ISO 19143 (Filter Encoding). Within the Open Geospatial Consortium, it underpins key standards like KML and the Sensor Web Enablement (SWE) suite, facilitating broad interoperability in web mapping and sensor networks.

Applications and implementations

The standard is widely implemented across government, commercial, and research sectors for spatial data infrastructure. National mapping agencies, like Ordnance Survey and the United States Geological Survey (USGS), use it for data exchange and publishing. It is the default encoding for data delivered via OGC Web Feature Service (WFS) interfaces and is fundamental to the INSPIRE Directive in the European Union for environmental data sharing. Software libraries such as GDAL and frameworks like GeoTools provide extensive support for reading and writing data, enabling its use in diverse platforms from Esri ArcGIS to open-source projects like QGIS.

Category:ISO standards Category:Geographic information systems standards Category:XML-based standards