Geospatial metadata

Geospatial metadata (also geographic metadata, or simply metadata when used in a geographic context) is a type of metadata that is applicable to objects that have an explicit or implicit geographic extent, in other words, are associated with some position on the surface of the Globe. Such objects may be stored in a geographic information system (GIS) or may simply be documents, datasets, images or other objects, services, or related items that exist in some other native environment but whose features may be appropriate to describe in a (geographic) metadata catalogue (may also be known as a data directory, data inventory, etc.).

Definition

ISO 19115 "Geographic Information - Metadata" [ISO 19115 Geographic Information - Metadata. International Organization for Standardization (ISO), Geneva, 2003] from ISO/TC 211, the current "best practice" standard for geospatial metadata, does not in fact provide a definition of geospatial (or geographic) metadata; however, uses the following wording in its "scope" section:

"This International Standard provides information about the identification, the extent, the quality, the spatial and temporal schema, spatial reference, and distribution of digital geographic data."

A little further, it is stated: "Though this International Standard is applicable to digital data, its principles can be extended to many other forms of geographic data such as maps, charts, and textual documents as well as non-geographic data."

The U.S. FGDC (Federal Geographic Data Committee) describes (geospatial) metadata as follows:

"A metadata record is a file of information, usually presented as an XML document, which captures the basic characteristics of a data or information resource. It represents the who, what, when, where, why and how of the resource. Geospatial metadata are used to document geographic digital resources such as Geographic Information System (GIS) files, geospatial databases, and earth imagery. A geospatial metadata record includes core library catalog elements such as Title, Abstract, and Publication Data; geographic elements such as Geographic Extent and Projection Information; and database elements such as Attribute Label Definitions and Attribute Domain Values." [ [http://www.fgdc.gov/metadata "Geospatial Metadata" on FGDC website, visited 16 October 2006] ]

History

The growing appreciation of the value of geospatial metadata through the 1980s and 1990s led to the development of a number of initiatives to collect metadata according to a variety of formats either within agencies, communities of practice, or countries/groups of countries. For example, NASA's "DIF" metadata format was developed during an Earth Science and Applications Data Systems Workshop in 1987 [ [http://gcmd.nasa.gov/User/difguide/whatisadif.html Gene Major and Lola Olsen: "A short history of the DIF". On GCMD website, visited 16 October 2006] ] , and formally approved for adoption in 1988. Similarly, the U.S. FGDC developed its geospatial metadata standard over the period 1992-1994 [ [http://libraries.mit.edu/guides/subjects/metadata/standards/fgdc.html MIT Libraries Guide: "Federal Geographic Data Committee (FGDC) Metadata". On MIT Libraries website, visited 16 October 2006] ] . ANZLIC, a combined body representing spatial data interests in Australia and New Zealand, released version 1 of its "metadata guidelines" in 1996 [ [http://www.anzlic.org.au/get/2358011755 ANZLIC Metadata Guidelines: Core metadata elements for geographic data in Australia and New Zealand, Version 2 (February 2001)] ] . The task of harmonizing the range of formal and "de facto" standards was undertaken by ISO/TC 211 over the approximate period 1999-2002, resulting in the release of ISO 19115 "Geographic Information - Metadata" in 2003. Individual countries, communities of practice, agencies, etc. are currently in the process of re-casting their previously-used metadata standards as "profiles" or recommended subsets of ISO 19115, optionally with the inclusion of additional metadata elements as formal extensions to the ISO standard. The growth in popularity of Internet Technologies and data formats, such as Extensible Markup Language (XML), during the 1990s led to the development of mechanisms for exchanging geographic metadata on the Web. In 2004, the Open Geospatial Consortium released the current version (3.1) of Geography Markup Language (GML) which is an XML grammar for expressing geospatial features and corresponding metadata. With the growth of the Semantic Web in the 2000s, the geospatial community has begun to develop ontologies for representing semantic geospatial metadata. Some examples include the [http://www.ordnancesurvey.co.uk/oswebsite/ontology/ Hydrology and Administrative ontologies] developed by the Ordnance Survey in the United Kingdom.

ISO 19115: international metadata standard for geographic information

(need description of ISO 19115 here)

Metadata directories (metadata catalogues, data directories)

(need discussion of, and subsections on GCMD, FGDC metadata gateway, ASDD, European and Canadian initiatives, etc. etc.)
* [http://gcmd.nasa.gov GCMD] - Global Change Master Directory's goal is to enable users to locate and obtain access to Earth science data sets and services relevant to global change and Earth science research. The GCMD database holds more than 20,000 descriptions of Earth science data sets and services covering all aspects of Earth and environmental sciences.

Geospatial metadata tools

There are many commercial GIS or geospatial products that support metadata viewing and editing on GIS resources. For example, ESRI's ArcGIS Desktop and Autodesk's AutoCAD Map 3D 2008 support geospatial metadata extensively.

[http://geonetwork-opensource.org GeoNetwork opensource] is a comprehensive Free and Open Source Software solution to manage and publish geospatial metadata and services based on international metadata and catalog standards. The software is part of the Open Source Geospatial Foundation's software stack.

References

[http://www.anzlic.org.au/get/2440920572.PDF ANZLIC Metadata Profile Version 1.0 (viewed 17 Sept. 2007)]

ee also

*Metadata
*Geographic information system
*ISO/TC 211

External links

* [http://www.fgdc.gov/metadata FGDC metadata page]
* [http://gcmd.nasa.gov/ Global Change Master Directory(GCMD)]