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OpenGIS Specifications and National System for Geospatial-Intelligence (NSG)

NGA Standards Document Features OGC Specifications

Wayland, MA, USA. February 20, 2007.

The U.S. Department of Defense National Geospatial-Intelligence Agency (NGA) has issued a document, "Enabling A Common Vision", which outlines the overall National System for Geospatial-Intelligence (NSG) standards baseline. Open Geospatial Consortium (OGC) Specifications figure prominently in this U.S. Federal and national baseline.

Shortly after September 11, 2001, the National Center for Geospatial Intelligence Standards (NCGIS) was formed by the NGA to develop and coordinate geospatial standards with other Department of Defense (DoD) agencies, other intelligence agencies, standards organizations, civil agencies, private industry, and foreign partners. These groups have worked with NCGIS to develop and mature a set of standards that enable data and service interoperability in the context of a service-oriented architecture (SOA).

As the document states, "The domestic civil community and the international community are implementing largely the same suite of common geospatial standards as the NSG. This architecture is particularly valuable to the Homeland Security community within the NSG, allowing it to share investments in geospatial data and knowledge related to critical infrastructure and natural environments with U.S. cities, counties and other organizations to support the prevention and mitigation of national disaster and security situations."

In "Enabling A Common Vision," the NSG has endorsed a set of key specifications known collectively as the OGC Spatial Data Infrastructure (SDI) 1.0 baseline. These OGC standards include the OpenGIS Specifications for Web Feature Service (WFS), Geography Markup Language (GML), Web Map Service (WMS), Styled Layer Descriptor (SLD), Catalogue Services (CS-Web), and Filter Encoding Specification (FE). Other standards included are ISO 19115 Geographic Information — Metadata, and ISO 19119 Geographics Information — Services.

NGA's position on standards stated in the document parallels a growing policy direction developing across the defense and intelligence community, and across many other communities of interest around the world, toward a greater mandate for open standards based, interoperable technology solutions.

The OGC is an international industry consortium of more than 335 companies, government agencies, research organizations, and universities participating in a consensus process to develop publicly available interface specifications. OpenGIS. Specifications support interoperable solutions that "geo-enable" the Web, wireless and location-based services, and mainstream IT. The specifications empower technology developers to make complex spatial information and services accessible and useful with all kinds of applications. Visit the OGC website at


Sam Bacharach
Executive Director, Outreach and Community Adoption
Open Geospatial Consortium, Inc.
35 Main Street, Suite 5, Wayland, MA 01778 USA
Tel: +1-703-352-3938

From the Report: GEOINT Standards Baseline


The NSG community is moving towards the formal adoption of the following key standards into the GEOINT standards baseline:

Web Features Service: The WFS implementation specification allows clients to retrieve and update geospatial data encoded in Geography Markup Language (GML) from multiple WFSs. It defines interfaces for data access and manipulation of geographic features, and through these interfaces, a web user or service can combine, use, and manage geodata.

Web Map Service (WMS): The WMS implementation specification supports the creation and display of registered and super-imposed maplike views (graphical images, such as GIF, JPEG, TIFF, and NITFS).

Web Map Context (WMC): The WMC implementation specification is a companion to WMS. It describes how to save a map view comprised of many different layers from different Web Map Services.

Web Coverage Service (WCS): The WCS specification allows access to geospatial 'coverages' (raster data sets) that represent values or properties of geographic locations rather than WMS-generated maps (pictures).

Geography Markup Language (GML): GML is eXtensible Markup Language (XML) encoding for the transport and storage of geographic information, including both the spatial and non-spatial properties of geographic features.

Styled Layer Descriptor (SLD): The SLD standard defines the structure of an XML file that applies rendering or symbolization rules to features. An SLD requests a WMS to present a map according to submitted style rules.

Catalog Services (CS-W): The CS-W provides abstract model and protocol-specific solutions for the discovery of geospatial resources. Through catalog metadata and query interfaces, metadata properties are returned to the requestor, often embedded with links to actual data or services that allow the catalog to act as a referral service to other information resources.

Filter Encoding Specification (FE): FE is used to express a query or filter using a predicate language, or terms and operators, stored in XML elements. FE is used in requests to WFS and queries to CS-W.

Additional standards included in the NSG baseline are:

  • ISO 19115 Geographic Information — Metadata: critical to making data discoverable and retrievable
  • ISO 19119 Geographic Information — Services: critical to defining where web services are deployed and used within an SOA
  • NSG Feature Data Dictionary and NSG Feature Catalog: critical to enabling the development of logical and physical data models.

Prepared by Robin Cover for The XML Cover Pages archive. See also: (1) the announcement "GEOINT Standards: Enabling a Common Vision"; (2) "Geography Markup Language (GML)."

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