OS MasterMap

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The OS MasterMap is the premier digital product of the Ordnance Survey. It was launched in November 2001. It is a database that records every fixed feature of Great Britain larger than a few meters 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. OS 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 for OS MasterMap data depends on: the total area requested, the layers licensed, the number of TOIDs in the layers, the period in years of the data usage.

Contents

OS MasterMap can be used to generate maps for a vast array of purposes. Although the scale on a digital map is much more flexible than a paper map, one can print out maps from OS MasterMap data with detail equivalent to a traditional 1:1250 paper map.

Ordnance Survey claims that OS MasterMap data is never more than six months out of date, thanks to continuous review. The scale and detail of this mapping project is so far unique. Around 440 million TOIDs have so far been assigned, and the database stands at 600 terabytes in size. [1]

Layers

Topography Layer

The OS MasterMap Topography Layer represents topography at a scale of 1:1250. It is further subdivided into a number of themes: land area classifications' buildings, roads, tracks and paths, rail, water, terrain and height, heritage and antiquities, structures; and administrative boundaries. [2]

Integrated Transport Network Layer

OS MasterMap® Integrated Transport Network™ (ITN) Layer maps Great Britain’s road network – from motorways, pedestrian streets, parks, reserves to museums. It contains attributes to enable the routing of vehicles, taking into account the limitations of the road network in general. [3]

OS MasterMap Address Layer 2

OS MasterMap Address Layer 2 is a dataset that describes the location of addresses. It is designed to be used as a means of geo-referencing addresses and attempts to improve on Address Point. Address Layer is a part of the National Spatial Address Infrastructure and contains National Land and Property Gazetteer attributes that classify properties. It is currently at the center of a dispute between Ordnance Survey and Intelligent Addressing, the custodian of the National Land and Property Gazetteer dataset. [4] [5]

Imagery Layer

The Imagery layer is a national collection of 25cm resolution aerial photos. [6]


Delivery Of The Geographical Data

OS MasterMap's data is in GML format. It is usually delivered as files compressed with gzip (providing them an extension ".gz"). [7]

Recently, Ordnance Survey has been trialing delivery of OS MasterMap data using WFS and WMS, in accordance with the Open Geospatial Consortium. This trial may even end up with automatic updates using WFS-T.

Custodianship Of The Data

Although branded like a commercial product, OS MasterMap, is in fact the UK’s most complete, accurate and up-to-date geographic record. By moving to purely digital media for mapping, Ordnance Survey brings upon itself the responsibility of being the sole mandatory custodian of Great Britain's official maps. Previously, by virtue of being a publication on paper, a copy of every edition of every paper map published by Ordnance Survey would have been deposited, by law, with each of the six legal deposit libraries in the UK. Although there is no such law in place for digital maps, the Ordnance Survey makes annual 'snapshots' of the data and voluntarily deposits with the legal deposit libraries:

If you are not a licensee and wish to view and undertake limited copying of historic versions of OS MasterMap data, then you may do so at one of the six Legal Deposit Libraries that hold annual 'snapshots' of large-scale Ordnance Survey data, which Ordnance Survey voluntarily deposits by Agreement with these Libraries. The data may only be accessed within the premises of one of these Libraries, and views and prints made from the data may only be used for purposes included within the exceptions to the Copyright Designs and Patents Act 1988.

Ordnance Survey website (Feb 2009)

The data, like any other, is susceptible to all the problems of computer data storage and digital preservation, for example: data corruption; the question of how often to take snapshots of the data (i.e. should every edit be recorded?); access to old versions of the data; practicable access to old versions of the data (after format changes, will new software be able to read old data?).

Related Research Articles

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<span class="mw-page-title-main">Topographic map</span> Medium to large scale map that shows a precise map of the terrain

In modern mapping, a topographic map or topographic sheet is a type of map characterized by large-scale detail and quantitative representation of relief features, usually using contour lines, but historically using a variety of methods. Traditional definitions require a topographic map to show both natural and artificial features. A topographic survey is typically based upon a systematic observation and published as a map series, made up of two or more map sheets that combine to form the whole map. A topographic map series uses a common specification that includes the range of cartographic symbols employed, as well as a standard geodetic framework that defines the map projection, coordinate system, ellipsoid and geodetic datum. Official topographic maps also adopt a national grid referencing system.

<span class="mw-page-title-main">Topography</span> Study of the forms of land surfaces

Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the land forms and features themselves, or a description or depiction in maps.

<span class="mw-page-title-main">Geography Markup Language</span> XML grammar for geographical features

The Geography Markup Language (GML) is the XML grammar defined by the Open Geospatial Consortium (OGC) to express geographical features. GML serves as a modeling language for geographic systems as well as an open interchange format for geographic transactions on the Internet. Key to GML's utility is its ability to integrate all forms of geographic information, including not only conventional "vector" or discrete objects, but coverages and sensor data.

<span class="mw-page-title-main">Ordnance Survey National Grid</span> System of geographic grid references used in Great Britain

The Ordnance Survey National Grid reference system (OSGB), also known as British National Grid (BNG), is a system of geographic grid references used in Great Britain, distinct from latitude and longitude.

In computing, the Open Geospatial Consortium Web Feature Service (WFS) Interface Standard provides an interface allowing requests for geographical features across the web using platform-independent calls. One can think of geographical features as the "source code" behind a map, whereas the WMS interface or online tiled mapping portals like Google Maps return only an image, which end-users cannot edit or spatially analyze. The XML-based GML furnishes the default payload-encoding for transporting geographic features, but other formats like shapefiles can also serve for transport. In early 2006 the OGC members approved the OpenGIS GML Simple Features Profile. This profile is designed both to increase interoperability between WFS servers and to improve the ease of implementation of the WFS standard.

A GIS file format is a standard for encoding geographical information into a computer file, as a specialized type of file format for use in geographic information systems (GIS) and other geospatial applications. Since the 1970s, dozens of formats have been created based on various data models for various purposes. They have been created by government mapping agencies, GIS software vendors, standards bodies such as the Open Geospatial Consortium, informal user communities, and even individual developers.

In computing, GeoServer is an open-source server written in Java that allows users to share, process and edit geospatial data. Designed for interoperability, it publishes data from any major spatial data source using open standards. GeoServer has evolved to become an easy method of connecting existing information to virtual globes such as Google Earth and NASA World Wind as well as to web-based maps such as OpenLayers, Leaflet, Google Maps and Bing Maps. GeoServer functions as the reference implementation of the Open Geospatial Consortium Web Feature Service standard, and also implements the Web Map Service, Web Coverage Service and Web Processing Service specifications.

<span class="mw-page-title-main">NaPTAN</span> Dataset of public transport acccess poiints in the UK

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A TOID is a unique reference identifier assigned by the Ordnance Survey to identify every topographical feature in Great Britain.

Address Point is a mapping/GIS data product supplied by Great Britain's national mapping agency, Ordnance Survey. It is based on the UK’s postal mail organisation, the Royal Mail, list of postal addresses, Postcode Address File (PAF). The most significant difference between Royal Mail list and Address Point is that Address Point includes the geographic coordinates of each postal address. This enables users to map the individual addresses.

The Integrated Transport Network (ITN) is a dataset containing details of Great Britain's transport network. Produced by Ordnance Survey – the national mapping agency of Great Britain – it forms part of the OS MasterMap suite of products.

gvSIG Desktop application for working with geographic data

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<span class="mw-page-title-main">Ordnance Survey</span> National mapping agency for Great Britain

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A national mapping agency (NMA) is an organisation, usually publicly owned, that produces topographic maps and geographic information of a country. Some national mapping agencies also deal with cadastral matters.

<span class="mw-page-title-main">Digimap</span>

Digimap is a web mapping and online data delivery service developed by the EDINA national data centre for UK academia. It offers a range of on-line mapping and data download facilities which provide maps and spatial data from Ordnance Survey, British Geological Survey, Landmark Information Group and OceanWise Ltd Ltd.,, Getmapping Ltd, the Environment Agency, OpenStreetMap, CollinsBartholomew Ltd, and various other sources.

Crown Copyright has been a long-standing copyright protection applied to official works, and at times artistic works, produced under royal or official supervision. In 2006, The Guardian newspaper's Technology section began a "Free Our Data" campaign, calling for data gathered by authorities at public expense to be made freely available for reuse by individuals. In 2010 with the creation of the Open Government Licence and the Data.gov.uk site it appeared that the campaign had been mostly successful, and since 2013 the UK has been consistently named one of the leaders in the open data space.

<span class="mw-page-title-main">Unique Street Reference Number</span>

The Unique Street Reference Number (USRN) is an eight-digit unique identifier for every street across Great Britain. 

References

  1. "All about OS MasterMap". MapServe.
  2. OS MasterMap Topography Layer
  3. OS MasterMap Integrated Transport Network Layer Archived 2011-11-21 at the Wayback Machine
  4. Article about AddressPoint in theguardian.com
  5. OS MasterMap Address Layer 2
  6. OS MasterMap Imagery Layer
  7. "OGC GML compressed (Export Format)". help.cadcorp.com. Retrieved 2024-02-04.