OS NGD Boundaries
A Lightning Talk
What are the layers in OS NGD Boundaries?
All of the layers in Boundary-Line, and all of the geometry, are present in the OS NGD Boundaries. How those layers are grouped is slightly different to those in the existing Boundary-Line product available from Ordnance Survey.
The main differences are:
Rationalising of different layers that have the same features but have previously appeared in different layers in Boundary-Line. These include Electoral Divisions and Regions
Creation of a complete Layer for Upper Tier Local Authorities so that customers do not need to take 2 layers and merge the relevant parts to create a single Upper Tier layer.
The Greater London Authority has been separated out from the old County layer into a new Regional Authority layer. This could later include geometry for some of the combined authorities such as WECA, WMCA, etc.
| OS NGD Layer | Boundary-Line Layer |
|---|---|
Boundary High Watermark | High Water |
Ceremonial County | Ceremonial_Counties |
Country | Country_Region |
Devolved Parliamentary Constituency | Scotland_Wales_Const |
Electoral Division | County_Electoral_Division Unitary_Electoral_Division |
GLA Assembly Constituency | Greater_London_Const |
Historic County | Historic_Counties |
Historic European Region | Historic_European_Region |
Lower Tier Local Authority | District_Borough_Unitary |
Parish or Community | Parish |
Region | English_Region Scotland_and_Wales_Region |
Regional Authority | County |
Upper Tier Authority | County District_Borough_Unitary |
Ward | Community_Ward District_Borough_Unitary_Ward |
Westminster Constituency | Westminster_Const |
Considerations with OS NGD Boundaries
Community Wards, which are unique to Welsh Communities have currently been added in with District Borough Unitary Wards to create the ‘Ward’ feature type.
These wards are not equivalent to each other and the two will likely be separated out in a later release of the data.
The equivalent Welsh boundaries to Wards can be found in the Electoral Divisions feature type
The Unitary Authorities and Metropolitan Boroughs that were previously only present in the District Borough Unitary layer in Boundary-Line have now been added to the old County Layer to create a complete Upper Tier Local Authorities layer
What formats does the OS NGD data come in?
The OS NGD Boundaries data comes in two formats, CSV and GeoPackage (GPKG)
The GeoPackage format comes ready to load into the GIS package of the users choice with different gpkg files for each layer.
The CSV format is more suited for loading into a database. It has all of the same layers in csv format and all the same attribution as the Geopackage, however instead of storing the geometry in a GIS ready format, it is stored as a MULTIPOLYGON attribute with all of the vertices stored as co-ordinate pairs in the text file
What is the attribution?
The attribution has changed from the Boundary-Line product:
All OS NGD data has an OSID
The features have a TOID, version, version date and changetype similar to the OS MasterMap family of products
There is a GSS Code for the ONS reference
Where boundaries are nested within larger boundaries (Wards within Districts within Counties) there is a set of ‘boundary parent reference’ attribution detailing the family tree of that boundary. These particular attributes only appear on layers where there is a nesting of features like this and go up to 4 levels of information depending on the layer
Attribute Comparison
Alongside the comparable attributes between OS NGD data and Boundary-Line (see below), there is also new attribution that covers:
Versioning
Parent relationships (similar concept to AddressBase),
Alternative languages
New IDs (OSID, TOID)
‘Has Detached Part’ and ‘Is Borough’ are also new Boolean attributes on certain layers
There are also some comparable attributes that have changed, so:
The Name field in Boundary-Line has values like ‘Salford District (B)’ in OS NGD the Name1 Text field has ‘Salford’, similarly ‘Brent London Boro’ is now ‘Brent’. These are now a closer match to the naming used by ONS, but not identical in such cases as ‘City of Southampton’
Are OS NGD Boundaries still OpenData?
The content of the OS NGD Boundaries Collection is OpenData under OGL Licence, however the OS NGD data is only accessible to PSGA members and OS Partners as these are the only customers with access to OS Select+Build
If a PSGA user downloads the OS NGD Boundaries collection from OS Select+Build they are able to share that data more widely as it is OpenData under OGL Licence
Boundary-Line and the OS NGD Boundaries Collection will continue to have identical geometry (but different attribution). However, until further notice Boundary-Line will be the only way non-PSGA members or OS Partners can access this data directly from the OS Data Hub
Links that may be useful:
This content has been developed from what was originally a Lightning Talk PowerPoint slide set. These slides are available to PSGA members to view and download from the PSGA members area of the OS website
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