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From OS OpenData developer wiki
About Boundaries
Introduction to Ordnance Survey data derived from the Boundary-Line™ product
Ordnance Survey data derived from the Boundary-Line™ product are administrative and electoral boundaries for England, Scotland and Wales. These include counties, unitary authorities, Westminster constituencies, wards and many more. They have been derived from Boundary-Line to ensure compatibility and good performance with web applications built using OS OpenSpace API. The geometry information is represented as vector digital data, supplied in GeoJSON format.
With Ordnance Survey data derived from the Boundary-Line™ product you can:
- Customise and style boundaries for your web site.
- Design thematic maps using your own or third party data.
- Inspire and amaze people with environmental, political and other social statistics.
- Experiment and innovate.
What is a boundary feature?
Ordnance Survey data derived from the Boundary-Line™ product are made up of boundaries are made up of 11,777 individual boundary areas known as features. Each feature has a unique ADMIN_UNIT_ID is made up of the following attributes:
- Boundary Line Name (NAME)
- Administrative boundary area (AREA_CODE)
- Census code (CENSUS_CODE)
- Geometry as XMIN YMIN XMAX YMAX (BOUNDING_BOX) This geometry information attribute is optional.
- Centroid of the feature as easting and northing as x,y (CENTROID)
- Resolution of data (RESOLUTION)
- Description of the boundary type (DESCRIPTION)
- Administrative Unit ID (ADMIN_UNIT_ID)
- Area of the feature in Hectares (HECTARES)
- Type Code (TYPE_CODE)
- Type Definition (TYPE DESCRIPTION)
Which Ordnance Survey data derived from the Boundary-Line™ product is available?
The following list shows:
OS OpenSpace boundary DESCRIPTION, (AREA_CODE) and feature count (number of boundary areas of this type)
- County, (CTY) 27
- County Electoral Division, (CED) 1739
- District, (DIS) 201
- District Ward, (DIW) 4585
- European Region, (EUR) 11
- Greater London Authority, (GLA) 1
- Greater London Authority Assembly Constituency, (LAC) 14
- London Borough, (LBO) 33
- London Borough Ward, (LBW) 649
- Metropolitan District, (MTD) 36
- Metropolitan District Ward, (MTW) 815
- Scottish Parliament Electoral Region, (SPE) 8
- Scottish Parliament Constituency, (SPC) 73
- Unitary Authority, (UTA) 110
- Unitary Authority Electoral Division, (UTE) 1334
- Unitary Authority Ward, (UTW) 1464
- Welsh Assembly Electoral Region, (WAE) 5
- Welsh Assembly Constituency, (WAC) 40
- Westminster Constituency, (WMC) 632
Are there high level administration relationships in Ordnance Survey data derived from the Boundary-Line™ product?
In England;
A County (CTY) is divided into Districts (DIS) which is divided into District Wards (DIW). For voting purposes a County is divided into Electoral Divisions (CED)
Unitary Authorities (UTA) are, for voting purposes, divided into Unitary Authority Wards (UTW) - except in the Isle of Wight, Cornwall, County Durham, Northumberland, Shropshire and Wiltshire where it is the Unitary Authority Electoral Division (UTE)
England also has Metropolitan Districts (MTD); these have no County administration. These Districts are divided for voting purposes into Metropolitan District Wards (MTW).
With the introduction of the regional government for London, in this document called the Greater London Authority (GLA); the proportional representation voting area for this new administration is the Greater London Authority Assembly Constituency (LAC). The existing London Borough (LBO) structure also has a relationship with the new Greater London Authority and each London Borough is divided for voting purposes into London Borough Wards (LBW).
In Scotland;
Unitary Authorities (UTA) are, for voting purposes, divided into Unitary Authority Wards (UTW).
The Scottish Parliamentary Electoral Region (SPE) is divided into Scottish Parliamentary Constituencies (SPC). Scotland is divided into Parliamentary Constituencies for voting purposes; to elect Members of the Scottish Parliament.
In Wales;
Unitary Authorities (UTA) are, for voting purposes, divided into Unitary Authority Electoral Divisions (UTE).
The Welsh Assembly Electoral Region (WAE) is divided into Welsh Assembly Constituencies (WAC). Wales is divided into Welsh Assembly Constituencies for voting purposes; to elect Assembly Members to the Welsh Assembly.
In Great Britain;
Great Britain is divided into European Regions (EUR) (Scotland, Wales and nine English regions) for voting purposes to elect members to the European Parliament.
England, Scotland, and Wales are divided into Westminster Constituencies (WMC) for voting purposes to elect members to the Westminster Parliament. Westminster Constituencies are made up of combinations of Wards (or Unitary Authority Electoral Divisions (UTE) in Wales), but they don't have consistent common boundaries.
Is there a lookup table of all the boundary features?
A lookup table (csv) is available to download from the forum with the following attributes:
NAME | CENSUS_CODE | ADMIN_UNIT_ID | AREA_CODE | DESCRIPTION | CENTROID
The NAME is the distinctive name of the boundary area.
The CENSUS_CODE data is created by the Office of National Statistics allows you to link Ordnance Survey data derived from the Boundary-Line™ product with census statistics. It can be used to identify a logical structure between certain boundary areas. For example District Wards nests into Districts which nests into Counties:
- County (CTY) - Hampshire, 24
- District (DIS) - Basingstoke and Deane District, 24UB
- District Ward (DIW) - Basing Ward, 24UBJX
The census codes are present as attributes for the following AREA_CODEs:
- CTY, DIS, DIW, LBO, LBW, MTD, MTW, UTA, UTE, UTW,
- The ADMIN_UNIT_ID is a unique identifier created by Ordnance Survey.
- The AREA_CODE is the name of the feature area type e.g. CTY
- The DESCRIPTION is the type description of the AREA_CODE e.g. County.
- The CENTROID is an x,y nominal centre coordinate of the feature
What is the meaning of Ordnance Survey data derived from the Boundary-Line™ product RESOLUTION?
Ordnance Survey data derived from the Boundary-Line™ product has been generalised at six different resolutions (RESOLUTION) to ensure that the vector data is appropriately scaled and maintains performance at different zoom levels.
The following data resolution by zoom level is detailed in a table (csv) in the forum and shows the resolutions available for all boundary areas by AREA_CODE.
| Zoom Level | Raster data shown boundaries | Resolution |
|---|---|---|
| 10 & 9 | Streetview | 5m |
| 8 & 7 | 1:50 000 | 20m |
| 6 & 5 | 1:250 000 | 200m |
| 4 & 3 | MiniScale (1:1M) | 500m |
| 2 | Overview | 1000m |
| 1 | Overview | 2000m |
| 0 | Overview | 5000m |
Are there any special characteristics of Ordnance Survey data derived from the Boundary-Line™ product?
Ordnance Survey data derived from the Boundary-Line™ product is derived from Ordnance Survey's dataset Boundary-Line and will still show the following characteristics:
Extent of the Realm (EOR)
This is where a boundary area is digitised on the alignment of the mean low water for the seaward extent. This is prevalent particularly around the estuaries of Great Britain. All Ordnance Survey data derived from the Boundary-Line™ product that extends into the sea include the EOR extent.
Area Values
The area values attribute (HECTARES) quoted is retained from the source data. Area values of each ADMIN_UNIT_ID in Ordnance Survey data derived from the Boundary-Line™ product include the Extent of the Realm (EOR).
Treatment of boundaries in estuaries
The extent of the realm (EOR) follows mean low water and crosses the estuaries at the level of the sea at low water. In this example showing Westminster Constituencies, an adjoining boundary also extends into the estuary.
Seaward extensions
These are artificial extensions to the realm. They extend the local government and parliamentary areas seaward.
Structures in the sea
Breakwaters are structures of wood, stone, metal or other material built to break the force of waves. They can be separate from, or joined to, the mainland. If joined, they are generally included in the local government and parliamentary areas. If separate, they are not part of the local government and parliamentary area unless they are placed therein by legislation of some kind, for example, Plymouth breakwater is included in the local government area whilst the centre portion of the Portland Harbour breakwater is not.
Permanent or solid structures in the sea, such as the forts in the Solent off Portsmouth Harbour and Brighton Marina, are usually included in local government and parliamentary areas.
Islands and rocks in the sea
The following rules govern the representation in Boundary-Line of offshore islands and rocks in the sea:
- If an offshore island or rock is shown, it will be contained within all the relevant administrative unit collections.
In this example, the Islands of Flat Holm and Steep Holm in the Mouth of the river Severn are contained within the Bristol North West Westminster Constituency.
Features with multi-part polygons
Where multiple polygons occur as part of the same feature then the CENTROID will be located at the nominal centre of the largest polygon in that feature.
OpenSpace Pro
What additional products are available for Openspace Pro?
- Zoom Map Stack - 10 layers of consistently styled mapping over a range of scales including OS VectorMap™ Local
- 1:25 000 Scale Colour Raster
- 1:50 000 Scale Colour Raster
Configuring OS OpenSpace Pro dataset requests
We have provided a method to request products using Product Codes. If you have an OpenSpace Pro licence, your application can request additional datasets including 1:25k. Each mapping product had a unique product code (see below).
In your OpenSpace code you will need to replace or comment out this piece of code that provides the default products:
//osMap = new OpenSpace.Map('map');
Replace it with code that requests products by Product Code. Its important to insert a correct sequence of product codes i.e Insert small scale products first (most zoomed out). To use product codes correctly they need to be ordered according to resolution, so the resolution order (as represented by the product codes) must be in high to low order.
In the following example, Vector Map District had been included:
var options = {products: ["OV0", "OV1", "OV2", "MSR", "MS", "250KR", "250K", "50KR", "50K", "VMDR", "VMD", "SVR", "SV"]};
osMap = new OpenSpace.Map('map',options);
In the following example, 50k, Vector Map District and StreetView are shown:
var options = {products: ["50KR", "50K", "VMDR", "VMD", "SVR", "SV"]};
osMap = new OpenSpace.Map('map',options);
How do I add 1:25k scale mapping (OpenSpace Pro/OS OnDemand WMTS only)?
If you have an OpenSpace Pro contract to licence 1:25k mapping, use the following product codes.
var options = {products: ["OV0", "OV1", "OV2", "MSR", "MS", "250KR", "250K", "50KR", "50K", "25KR", "25K", "SVR", "SV"]};
osMap = new OpenSpace.Map('map',options);
What are OpenSpace Pro Product Codes?
In order to achieve a friendly zoomed in/out effect, each product type has a suitable resolution measured in meters per pixel at which it should be viewed in a web application.
Each product type (except Overview maps) has been provided at two zoom levels or resolutions. When a product is Resampled it is twice the original resolution. 'R' denotes a resampled product.
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Open source Installation
Is the technology used to build OS OpenSpace available for me to host my own application?
Yes, the OS OpenSpace API created by Ordnance Survey is built using freely available third party open source software including the Ordnance Survey API, all of which are detailed in the Open Source Software and Licences page.
The Ordnance Survey API proprietary code, supporting documentation and build instructions has been released as OSGB Web Map Tools and is free to download from SourceForge.net
The project page on Sourceforge: http://sourceforge.net/projects/osgbwebmaptools/
Main documentation website: http://osgbwebmaptools.sourceforge.net
Although the OSGB Web Map Tools project does not provide free access to Ordnance Survey data sets, it has been designed specifically to work with Ordnance Survey data. To use Ordnance Survey data you will need a data licence. Ordnance Survey has a wide range of data licences available for businesses and other commercial requirements.
For more information see: http://ordnancesurvey.co.uk/oswebsite/business/
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Are there any restrictions using OSGB Web Map Tools?
The OSGB Web map tools project is released under a permissive free licence, specifically a BSD-style licence.
