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'Ordnance Survey' (OS) is an executive agency of the United Kingdom government. It is the national mapping agency for Great Britain,^[1] and one of the world's largest producers of maps.

Contents

Origins

The 20th century

UK map range

Cartography

Ordnance Survey of Scotland

OS MasterMap

Geographical information science research at Ordnance Survey

Criticisms of Ordnance Survey

See also

References

Footnotes

External links

Origins

The roots of Great Britain's 'Ordnance Survey' (OS) go back to 1747, when King George II commissioned a military survey of the Scottish highlands following the Jacobite revolt of 1745. William Roy was the engineer responsible for this pioneering work; one of the staff involved was noted artist Paul Sandby. It was not until 1790 that the Board of Ordnance (the predecessor of the Ministry of Defence) began a national military survey starting with the south coast of England in anticipation of a French invasion.
By 1791, the Board had purchased the new Ramsden theodolite, and work began on mapping southern Great Britain using a baseline that Roy himself had previously measured and that crosses the present Heathrow Airport. A set of postage stamps, featuring maps of the Kentish village of Hamstreet, was issued in 1991 to mark the bicentenary.
In 1801 the first one-inch-to-the-mile (1:63,360) map was published, detailing the county of Kent, with Essex following shortly after.
During the next twenty years roughly a third of England and Wales was mapped at the same scale. (see Principal Triangulation of Great Britain.) It was gruelling work: Major Thomas Colby, later the longest serving Director General of the Ordnance Survey, walked 586 miles in 22 days on a reconnaissance in 1819. In 1824, Colby and most of his staff moved to Ireland to work on a six-inches-to-the-mile (1:10,560) valuation survey.
Colby was not only involved in the design of specialist measuring equipment. He also established a systematic collection of place names, and reorganised the map-making process to produce clear, accurate plans. He believed in leading from the front, travelling with his men, helping to build camps and, as each survey session drew to a close, arranging mountain-top parties with enormous plum puddings.
After the first Irish maps came out in the mid-1830s, the Tithe Commutation Act 1836 led to calls for similar six-inch surveys in England and Wales. After official prevarication, the development of the railways added to pressure that resulted in the 1841 Ordnance Survey Act. This granted a right to enter property for the purpose of the survey. Following a fire at its headquarters at the Tower of London in 1841, the OS was in disarray for several years with arguments about which scales to use. Major-General Sir Henry James was by then Director General, and he saw how photography could be used to make maps of various scales cheaply and easily. He developed and exploited photozincography not only to reduce the costs of map production but also to publish 'facsimiles' of National Manuscripts. Between 1861 and 1864 a 'facsimile' of the medieval Domesday Book was issued, county by county.
After the fire, the OS relocated to a site in Southampton, and the twenty-five inch to the mile survey was completed by 1895.

The 20th century

During the First World War the OS was involved in preparing maps of France and Belgium for its own use, and many more maps were created during World War II, including :

★ 1:40,000 map of Antwerp, Belgium

★ 1:100,000 map of Brussels, Belgium

★ 1:5,000,000 map of South Africa

★ 1:250,000 map of Italy

★ 1:50,000 map of Northeast France

★ 1:30,000 map of the Netherlands with manuscript outline of German Army occupation districts
After the war Colonel Charles Close, then Director General, developed a marketing strategy using covers designed by Ellis Martin to increase sales in the leisure market. In 1920 O. G. S. Crawford was appointed Archaeology Officer and played a prominent role in developing the use of aerial photography to deepen understanding of archaeology.
In 1935 the Davidson Committee was established to review the Ordnance Survey's future. The new Director General, Major-General Malcolm MacLeod, started the retriangulation of Great Britain, an immense task involving erecting concrete ''triangulation pillars'' (trig points) on prominent (often inaccessible) hilltops throughout Great Britain. These were intended to be infallibly constant positions for the theodolites during the many angle measurements, which were each repeated no less than 32 times.
The Davidson Committee's final report set the OS on course for the twentieth century. The national grid reference system was launched, with the metre as its unit of measurement. An experimental 1:25,000 scale map was introduced. The one-inch maps remained for almost forty years before being superseded by the 1:50,000 scale series, as proposed by William Roy more than two centuries earlier.
The OS had outgrown its site in the centre of Southampton (made worse by the bomb damage of the Second World War), and in 1969 moved to the suburb of Maybush, towards the edge of the city, where it remains today. Some of the remaining buildings of the original city-centre site are now used as part of the court complex.
In 1995 the Ordnance Survey digitised the last of about 230,000 maps, making the United Kingdom the first country in the world to complete a programme of large-scale electronic mapping. The OS is now a civilian organisation with executive agency status.

UK map range

Ordnance Survey maps are available in most bookshops, in a variety of scales:

★ ''Route'' (1:625,000) - Designed for long-distance road users. One double-sided map (dark blue cover) covers the whole of Great Britain.

★ ''Road'' (1:250,000) - Designed for road users. They have green covers; 8 sheets cover the whole of Great Britain.

★ ''Landranger'' (1:50,000) - The "general purpose" map. They have pink covers; 204 sheets cover the whole of Great Britain and the Isle of Man.

★ ''Explorer'' (1:25,000) - Specifically designed for walkers and cyclists. They have orange covers; 403 sheets cover the whole of Great Britain (the Isle of Man is excluded from this series). Explorer maps have replaced two older series of 1:25,000 map:

★
★ ''Outdoor Leisure'' - Also for walkers and cyclists. These 33 maps specifically covered tourist destinations. Identified by their yellow covers and often double-sided, they predated the Explorer maps. They covered a larger area than Pathfinders. Those Explorer maps that have replaced OL maps still retain the OLnn map numbers.

★
★ ''Pathfinder'' - Pathfinders, with their green covers, were the predecessors to the Explorer series. These maps were smaller than the new ones and generally had no overlap between adjacent sheets. There were over 1,300 maps in the series. Some Pathfinders were phased out by the arrival of Outdoor Leisure maps, the remainder being later replaced by the new Explorer series.

★ ''Explorer Active'' (1:25,000) - the Explorer maps are also available in a plastic-laminated waterproof version.
Also produced are various historical and archaeological maps, and road maps of certain popular "tourist" areas, all at a variety of scales. The Ordnance Survey produces a free mapping index, showing which parts of the country are covered by which maps.
One series of historic maps is a reprint of the OS first series from the mid 19th century, but re-scaled to 1:50000, re-projected to the Landranger projection, and given 1 km gridlines. This means the that features from over 150 years ago fit exactly over their modern equivalents, and modern grid references can be given to old features.
The Ordnance Survey also produces more detailed mapping at 1:10,000 and 1:1,250 scales, which is available from some of the more specialist outlets. This is produced to order from digital data, so the customer can choose exactly which area the map should cover.
The digitisation of the data has allowed the OS to experiment with selling maps electronically. Several companies are now licensed to produce the popular scales (1:50000 and 1:25000) of map on CD/DVD or to make them available online for download. The buyer typically has the right to view the maps on a PC, a Laptop and a pocket PC/smartphone, and to print off any number of copies. The accompanying software is GPS-aware, and the maps are ready-calibrated. Thus, the user can quickly transfer a desired area from their PC to their laptop or smartphone, and go for a drive or walk with their postion continually pinpointed on the screen. The price for an individual map is much dearer than the equivalent paper version, but the price per square km falls rapidly with the size of coverage bought. For instance, it is possible to buy a CD of 1:50000 (Landranger) mapping for all the national parks for less than £20, or a DVD of the whole of Britain (ie excluding Northern Ireland) for a little above £100. Explorer-scale maps are much more expensive.

Cartography

Main articles: British national grid reference system

The original maps were made by triangulation. For the second survey, in 1934, this process was used again, and resulted in the building of many triangulation pillars (trig points): short (approx 4 feet/1.2 m high), usually square, concrete or stone pillars at prominent locations such as hill tops. Their precise locations were determined by triangulation, and the details in between were then filled in with less precise methods. Modern Ordnance Survey maps are based on aerial photographs, but large numbers of the pillars remain.
The OS still maintains a set of master geodetic reference points to tie the OS geographic datums to modern measurement systems including GPS. The Ordnance Survey maps of Great Britain do not use latitude and longitude to indicate position but a special grid. The grid is technically known as 'OSGB36'™ (Ordnance Survey Great Britain 1936), and was introduced after the retriangulation of 1936–53.

Ordnance Survey of Scotland

Initially the Ordnance Survey of Scotland was a separate series of Maps with some sheet numbers in the 1945 series overlapping the OS of England and Wales. The 1926 Scotland series did not publish the English sheets on the back of the dust cover, later sheets based on this survey gained the National Grid in 1936 previously sheets were split into large squares with Letters going West -> East and Numbers North -> South.
From the 1964 Aerial Photography based series onwards the OS of Scotland and England and Wales were combined.

OS MasterMap

The Ordnance Survey's flagship digital product, launched in November 2001, is OS MasterMap. This is a database that records every fixed feature of Great Britain larger than a few metres in one continuous digital map. Every feature is given a unique TOID (topographical identifier), a simple identifier that includes no semantic information. Typically each TOID is associated with a polygon that represents the area on the ground that the feature covers, in National Grid coordinates. MasterMap is offered in themed "layers", for example, a road layer and a building layer, each linked to a number of TOIDs. Pricing of licenses to MasterMap data depends on the total area requested, the layers licensed, the number of TOIDs in the layers, and the period in years of the data usage.
MasterMap can be used to generate maps for a vast array of purposes, and maps can be printed from MasterMap data with detail equivalent to a traditional 1:1250 paper map.
The OS claims that MasterMap data is never more than 6 months out of date, thanks to continuous review(how to review). The scale and detail of this mapping project is unique. Around 440 million TOIDs have so far been assigned, and the database stands at 600 gigabytes in size. MasterMap is currently (August 2005) at version 6.
The OS is encouraging users of its old OS Landline data to migrate to MasterMap and in June 2007 announced a notice of withdrawal for this product as of 30th September 2008 http://www.ordnancesurvey.co.uk/oswebsite/products/landline/.

Geographical information science research at Ordnance Survey

Since about 2001 Ordnance Survey has had a Research & Innovation department (renamed Ordnance Survey Research Labs in 2007) that is very active in several areas of geographical information science, including:

★ Spatial cognition

★ Map Generalisation

★ Spatial Data Modelling

★ Remote sensing and analysis of remotely sensed data

★ Semantics and ontologies
Ordnance Survey actively supports the academic research community through its External Research and University Liaison team. The R&I department actively supports MSc and PhD students as well as engaging in colloborative research. Most Ordnance Survey products are available to UK Universities that have signed up to the Digimap agreement and data is also made available for research purposes that advances Ordnance Survey's own research agenda.
More information can be found at Ordnance Survey Research Labs

Criticisms of Ordnance Survey

In recent years there have been a number of criticisms of Ordnance Survey. Most of these centre on the argument that OS possesses a virtual government monopoly on geographic data in the UK.^[2] Although OS is a government agency it is required to act as a "trading fund" or commercial entity. This means that it is totally self funding from the commercial sale of its data whilst at the same time being the public supplier of geographical information.
The Guardian newspaper has a long-running "Free Our Data" campaign, calling for the raw data gathered by - and for, often by local authorities, at public expense - the OS to be made freely available for reuse by individuals and companies, as happens, for example, with such data in the USA. ^[3] although this argument frequently omits to make any comparison between the quality of the data available from these sources.
On the 7 April 2006 the Office of Public Sector Information (OPSI) received a complaint from the data management company Intelligent Addressing^[4]. Many, although not all, complaints were upheld by the OPSI, one of the conclusions being that OS "is offering licence terms which unnecessarily restrict competition". Negotiations between OS and interested parties are ongoing with regard to the issues raised by the OPSI report, the OS being under no obligation to comply with the report's recommendations.

See also

★ Equivalent agencies here

★
★ Nationaal Geografisch Instituut - Institut Géographique National - Belgium (see articles on and )

★
★ Natural Resources Canada

★
★ Institut géographique national (France) France

★
★ Ordnance Survey Ireland

★
★ Ordnance Survey of Northern Ireland

★
★ Istituto Geografico Militare Italy ()

★
★ INEGI (Mexico)

★
★ Topografische Dienst Kadaster the Netherlands ()

★
★ Statens kartverk Norway ()

★
★ Wojskowy Instytut Geograficzny in Poland (1819-1939)

★
★ Lantmäteriverket in Sweden ().

★
★ Swisstopo – Switzerland

★
★ United States Geological Survey

★ Grid reference

★
★ British national grid reference system

★
★ Irish national grid reference system

★ Cartography (map making)

★ Hydrography

★
★ Hydrographic survey

★
★ United Kingdom Hydrographic Office

★ Romer

★ Sea level

★ UK topics

★ Maps of the UK and Ireland

References

★ Old Series Ordnance Survey Maps of England and Wales, Margary, Harry, , , Unknown, 1992, ISBN 0-903541-01-7

★ Official Homepage

★ History of Cartography

Footnotes

1. Note that the Ordnance Survey currently deals only with maps of Great Britain (and to an extent, the Isle of Man). Northern Ireland, although part of the United Kingdom, is mapped by a separate government agency, the Ordnance Survey of Northern Ireland.
2. Guardian
3. Free Our Data website
4. OPSI

External links

★ Ordnance Survey

★ old-maps.co.uk 19th century Ordnance Survey maps of the whole of Great Britain

★ 19th century Ordnance Survey maps of Lancashire

★ National GPS network information: A guide to coordinate systems in Great Britain

★ OS MasterMap official site

★ Ordnance Survey Platinum Partner: Source for OS digital mapping

★ The Guardian: Devil is in the detail as OS maps out the future by Paul Brown, March 8, 2004

★ Royal Engineers Museum - Survey -origins of the Ordnance Survey

★ Royal Engineers Museum - General Roy -Biography

★ [1] History of Ordnance Survey

★ Scans of the OS Popular Edition - England and Wales (1920-30s)

★ Scans of the OS New Popular Edition - England and Wales (1940-50s)