Introduction
This information note has been created to inform users on the geographic extents, resolution, release frequency, and formats for several types of NRS spatial datasets.
Geographic Extent
There are two types of extent that spatial data is provided in.
NRS Geography work on Total Extent boundaries, and provide the majority of spatial data 'Clipped to the coastline' which are to the Mean High-Water Mark, using the relevant Ordnance Survey Boundary-Line High Water Polyline and remove inland water as listed in the Standard Area Measurements produced by the Office for National Statistics
Clipped to the Coastline (Mean High Water with inland removed)
These are to the mean high water shown to the normal tidal limit (the point at which the level of a river or stream ceases to be affected by the tidal flow). Clipped to the coastline boundaries closely represent map users’ expectations of how a coastal boundary should look.
Further information on the coastlines used can be obtained in the Ordnance Survey Boundary-Line User Guide.
Information on standard area measurements is available in the Geography Policy section of the National Records of Scotland website.
Examples of differing coverage
The coastline of Aberdeen City extends out to the statutory seaward extension in the Total Extent, compared with the Clipped to the coastline. The inland water for the River Don and the River Dee, as well as Aberdeen Harbour have been removed in the Clipped to the coastline.
In the next example, the inland water of Loch Lomond is included in the Total Extent, compared with the inland water removed as depicted in Clipped to the coastline where you can see the individual islands within Loch Lomond.
Resolution
NRS Geography boundary products are produced to full resolution which is the most detailed representation of actual boundaries.
NRS Geography are aware that users will have different requirements for levels of generalisation which is why we do not supply generalised boundaries. If you have access to ArcGIS, you can use the 'simplify' tool. If you have QGIS you can use the 'simplify geometries' tool. There are also free online tools that can be used to generalise a boundary.
Product Release Type Frequency
Scottish Postcode Directory
Scottish Postcode Directory boundaries and grid references (postcode unit, sector, and district) are subject to continuous change and are released bi-annually.
Settlement and Locality
Settlement and Locality datasets are only created at specific time points based on a set of published SPD postcode boundaries.
Island
The Island boundary dataset is subject to periodic change (e.g., when an island that has never been inhabited is now inhabited) and will be created at the time of change.
Civil Parish
The Civil Parish boundary dataset is an archived geography and there are no plans for updates to it. If NRS Geography are advised of errors on this map, it will be investigated and fixed, as necessary.
Census (Output Area, Census Island Groups)
Census boundary and grid reference datasets are based on postcode boundaries frozen at a point in time every ten years.
Formats
Our spatial data is available on the NRS website in Esri shapefile format within a Zipped file. NRS spatial data is also available as WFS via the Scottish Spatial Data website SpatialData.gov.scot
