Ordnance Survey of Northern Ireland

It was an Executive Agency within the Department of Culture, Arts and Leisure in the Northern Ireland Executive.

The Ordnance Surveys of Northern Ireland, Great Britain and the Republic of Ireland share a common heritage: the British Ordnance Survey (OS) ceased to map Ireland just before the creation of the Irish Free State in 1922 (the Partition of Ireland having already taken place in May 1921 with the creation of Northern Ireland).{{Citation needed|date=June 2025}} The new Ordnance Survey of Northern Ireland (OSNI) officially came into existence on 1 January 1922,{{Cite web |title=Ordnance Survey of Northern Ireland |url=https://discovery.nationalarchives.gov.uk/details/r/fddd961f-f5dc-45e2-a99d-e378ceb1be8e |access-date=30 June 2025 |website=The National Archives |quote=The official mapping organisation of the province of Northern Ireland, founded in January 1922.}} while the new Ordnance Survey of Ireland (OSI) came into being slightly later, on 1 April 1922.{{Citation needed|date=June 2025}}

The vast majority of OSNI's income came from the licensing of its digital mapping data, which, because of the long history of mapping in Ireland (see Ordnance Survey) is amongst the most detailed and comprehensive in the world.

Digital products range from the Large Scale (1:1250 urban and 1:2500 rural) vector database, 1:10,000 raster mapping derived automatically from the L/S vector, 1:50,000 and 1:250,00 vectors, 1;10,000 orthophotography, 1:25,000 leisure maps, the 1:50,000 raster series, 1:250,000 Ireland North raster, street maps of the main conurbations, as well as paper derivatives of all the raster products.{{Citation needed|date=June 2025}}

In 2005 OSNI began, with the Public Records Office of Northern Ireland (PRONI), to digitise the complete set of historical maps dating back to the 1830s. (The earliest comprehensive and accurately surveyed large scale mapping in the world). These are being georectified to match modern mapping projections and are being annotated with points of interest from PRONI's archives.{{Citation needed|date=June 2025}}

OSNI also maintained the UK's only common address database, Pointer, which cross matches and validates the address data from the Royal Mail, Valuation and Lands Agency, OSNI and local authorities, and georeferences each address, as well as giving it a unique identifier.{{Cite report |url=https://ggim.un.org/knowledgebase/Attachment233.aspx?AttachmentType=1 |title=Spatial Data Infrastructures in The United Kingdom: State of play 2011 |last=Vandenbroucke |first=Danny |last2=Biliouris |first2=Dimitrios |date=1 September 2010 |publisher=KU Leuven |page=7 |id=rcr11UKv122 |quote=LPS via OSNI also maintains the UK's only common address database, Pointer, which cross matches and validates the address data from the Royal Mail, Valuation and Lands Agency, OSNI and local authorities, and georeferences each address, as well as giving it a unique identifier.}} This allows spatial interrogation by customers of the >800,000 addresses in NI using computerised Geographic Information Systems (GIS) combined with digital mapping and the customer's own data.{{Citation needed|date=June 2025}}

Supporting the interconnectivity of Geographical Information (GI) for the benefit of the Northern Ireland economy, society and administration was OSNI's primary purpose. In support of this, OSNI also provides the secretariat for Mosaic, the GI strategy for Northern Ireland, which is the first such strategy to be implemented in the UK. In support of Mosaic, OSNI is currently (2006) building a GeoHub for the region, which will be able to host and connect to spatial data from multiple sources, permit a metadata (data about the data) search and, using thin client browser applications, via the Internet, permit multiple data layers to be interrogated, connected, analysed, licensed, downloaded, uploaded and updated.{{Citation needed|date=June 2025}}

Starting in Spring 2006, OSNI's own full product range became available via a map-enabled e-commerce website. OSNI's surveying technology is based on both photogrammetry and ground survey using total station electronic theodolites in combination with pen (tablet) computers, so that the data is updated directly into the digital format. The photogrammetry (using flight-derived stereo imagery at high resolution) is also used to maintain height models of the topography (Digital Terrain Model or DTM). Computer software permits the draping of aerial photography and/or mapping over such models for the purposes of fly-through or drive-through 3D visualisations.

OSNI's Geodesy section maintains the positional reference system to millimetre precision and OSNI's ground stations allow high accuracy use of GPS.{{Citation needed|date=June 2025}}

==See also==

• Irish grid reference system, the old coordinate system for Ireland.
• Irish Transverse Mercator, the new coordinate system.
• Ordnance Survey
• Ordnance Survey Ireland
• List of Government departments and agencies in Northern Ireland

• [http://www.osni.gov.uk/ Official website]

Category:Geography of Northern Ireland

Category:Northern Ireland Executive

Category:National mapping agencies

Category:Ordnance Survey