Geospatial metadata

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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.).

1 Definition
2 History
3 ISO 19115: international metadata standard for geographic information
4 Metadata directories (metadata catalogues, data directories)
5 Geospatial metadata tools
6 References
7 See also
8 External links

[edit] Definition

ISO 19115 "Geographic Information - Metadata"^[1] 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."^[2]

[edit] 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^[3], and formally approved for adoption in 1988. Similarly, the U.S. FGDC developed its geospatial metadata standard over the period 1992-1994^[4]. ANZLIC, a combined body representing spatial data interests in Australia and New Zealand, released version 1 of its "metadata guidelines" in 1996^[5]. 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.