A spatial data infrastructure (SDI) is a framework of spatial data, metadata

Metadata

The term metadata is an ambiguous term which is used for two fundamentally different concepts . Although the expression "data about data" is often used, it does not apply to both in the same way. Structural metadata, the design and specification of data structures, cannot be about data, because at...

, users and tools that are interactively connected in order to use spatial data in an efficient and flexible way. Another definition is the technology, policies, standards, human resources, and related activities necessary to acquire, process, distribute, use, maintain, and preserve spatial data.

A further definition is given in Kuhn (2005):

An SDI is a coordinated series of agreements on technology standards, institutional arrangements, and policies that enable the discovery and use of geospatial information by users and for purposes other than those it was created for.

General

Some of the main principles are that data and metadata should not be managed centrally, but by the data originator and/or owner, and that tools and services connect via computer network

Computer network

A computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communication channels that allow sharing of resources and information....

s to the various sources. A GIS is often the platform for deploying an individual node within an SDI. To achieve these objectives, good coordination between all the actors is necessary and the definition of standards is very important.

Due to its nature (size, cost, number of interactors) an SDI is usually government-related. An example of an existing SDI is the National Spatial Data Infrastructure (NSDI) in the United States. At the European side, INSPIRE

Infrastructure for Spatial Information in the European Community

INSPIRE is "an EU initiative to establish an infrastructure for spatial information in Europe that will help to make spatial or geographical information more accessible and interoperable for a wide range of purposes supporting sustainable development"....

 is a European Commission

European Commission

The European Commission is the executive body of the European Union. The body is responsible for proposing legislation, implementing decisions, upholding the Union's treaties and the general day-to-day running of the Union....

 initiative to build a European SDI beyond national boundaries and ultimately the United Nations Spatial Data Infrastructure UNSDI

UNSDI

is an initiative of the .UNSDI is an institutional and technical mechanism for establishing system coherence for the exchange and applications of geospatial data and information for UN activities and supporting SDI development activities in Member Countries....

 will do the same for over 30 UN Funds, Programmes, Specialized Agencies and member countries.

Software components

A SDI should enable the discovery and delivery of spatial data from a data repository, via a spatial service provider, to a user. As mentioned earlier it is often wished that the data provider is able to update spatial data stored in a repository. Hence, the basic software components of an SDI are:

1. a software client - to display, query, and analyse spatial data (this could be a browser or a Desktop GIS),
2. a catalogue service - for the discovery, browsing, and querying of metadata or spatial services, spatial datasets and other resources,
3. a spatial data service - allowing the delivery of the data via the Internet,
4. processing services - such as datum and projection transformations,
5. a (spatial) data repository - to store data, e.g. a Spatial database
   Spatial Database
   A spatial database is a database that is optimized to store and query data that is related to objects in space, including points, lines and polygons. While typical databases can understand various numeric and character types of data, additional functionality needs to be added for databases to...
   
   ,
6. GIS software (client or desktop) - to create and update spatial data

Besides these software components, a range of (international) technical standards are necessary that allow interaction between the different software components. Among those are geospatial standards defined by the Open Geospatial Consortium

Open Geospatial Consortium

The Open Geospatial Consortium , an international voluntary consensus standards organization, originated in 1994. In the OGC, more than 400 commercial, governmental, nonprofit and research organizations worldwide collaborate in a consensus process encouraging development and implementation of open...

 (e.g. OGC WMS, WFS, GML etc.) and ISO (e.g. ISO 19115) for the delivery of maps, vector and raster data, but also data format and internet transfer standards by W3c consortium.

See also

• GEOSS
• GMES
  GMES
  Global Monitoring for Environment and Security is a joint initiative of the European Commission and European Space Agency, which aims at achieving an autonomous and operational Earth observation capacity....
  
  
• Global Spatial Data Infrastructure
• INSPIRE
• UNSDI
  UNSDI
  is an initiative of the .UNSDI is an institutional and technical mechanism for establishing system coherence for the exchange and applications of geospatial data and information for UN activities and supporting SDI development activities in Member Countries....
  
  
• GIS software
  GIS software
  The umbrella term GIS software refers to a geographic information system application, which is software used to create, manage, analyze and display geospatial data on digital maps...
  
  

External links

• Blog Chilean Spatial Data Infrastructure
• GSDI 11 World Conference: The Geo-Spatial event of 2009, Rotterdam The Netherlands
• Global Spatial Data Infrastructure (GSDI) Association
• Links to SDI initiatives from the GSDI Association website
• The United Nations Spatial Data Infrastructure (UNSDI)
• The Netherlands Coordination Office of UNSDI (UNSDI-NCO)
• The GeoNetwork portal of UNSDI-NCO (with over 17.800 metadata sets)
• US National Spatial Data Infrastructure
• Australian Spatial Data Infrastructure
• The Centre for Spatial Data Infrastructures & Land Administration
• Canadian Geospatial Data Infrastructure
• Chilean Spatial Data Infrastructure
• The European INSPIRE initiative
• Spatial Data Infrastructures Unit at the EU Joint Research Centre
• Finnish National Spatial Data Infrastructure
• German National Spatial Data Infrastructure
• Dutch Geo register
• Laboratory of Geo-Information Science and Remote Sensing
• Spanish National Spatial Data Infrastructure (IDEE)
• Catalonia Spatial Data Infrastructure
• Gipuzkoa Spatial Data Infrastructure
• Andalusian Spatial Data Infrastructure
• SNIG - Portuguese National System for Geographic Information
• Canary Islands Spatial Data Infrastructure (IDECanarias)
• Andorran Spatial Data Infrastructure (IDEAnd)

SDI related journals

• International Journal of Spatial Data Infrastructure Research

SDI related books

• The SDI Cookbook from the Global Spatial Data Infrastructur Organisation (GSDI)
• Research and Theory in Advancing Spatial Data Infrastructure Concepts
• GIS Worlds: Creating Spatial Data Infrastructures
• Building European Spatial Data Infrastructures