Building Part and Building Line Feature Types

A Lightning Talk

What are the layers in OS NGD Buildings?

There are four feature types in the OS NGD Buildings theme. The first two have the same geometry as their equivalent features in OS MasterMap Topography Layer but all with new OS NGD attribution and are covered on this page. The third, added in September 2023, is comprised of merged Building Part features. The fourth, added in March 2025, is newly captured data about access points to certain key public buildings and are covered in the Building Feature Type section.

Building

Building

Polygon features representing either a complete separate building or a larger building where internal divisions have been dissolved to leave single feature. such as with a hospital or school.

Building Part

Building Part

Polygon features representing either a complete separate building or part of a larger building where internal divisions exist from ground to roof level and can be identified externally. Examples include a multi-storey car park, castle or a residential property.

Building Line

Building Line

A feature which has a line geometry a represents a wall between two buildings, internal building division or an overhanging building edge.

Building Access Point

Building Access Point

Access point to an entrance to a major public building (shopping centre, sports stadium, etc.), including attribution as to the type of access.

What formats does the OS NGD Building data come in?

The OS NGD Buildings 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 LINESTRING (Building Line), or POLYGON (Building Part/ Building) attribute with all of the vertices stored as co-ordinate pairs in the text file.

What is the attribution?

The OS NGD Buildings attribution varies between the Feature Types. However:

• All OS NGD data has an OSID, version, version date and changetype

• Where the data has an ancestry from OS MasterMap there is a TOID

• The data now has source, evidence and update dates so users can see where the information has come from and when it was updated

• There is also extra data around if the feature is obscured and the specification it was captured to

Example attribution for a building part feature

Building Heights

Where data was present in the Building Heights Attribution that data has been included against Building Part polygons

• Absolute Height Roof Base. The height, above datum, of the base of the roof, that is, where the roof intersects the building walls

• Relative Height Roof Base. The difference in height between the intersection of the external building walls and the underlying ground surface and the base of the roof of the building

• Absolute Height Maximum. The height, above datum, of the highest point of the building, this could include a chimney or other structure on a building

• Relative Height Maximum. The difference in height between the intersection of the external building walls and the underlying ground surface and the highest point on the building

• Absolute Height Minimum. The height, above datum, of the underlying ground surface

• Height Confidence Level. The confidence in the quality of the height attributes for the building or structure expressed in qualitative terms

Building Height explained digramatically

Land Use and Land Cover

There is a series of newly released attribution, and attributes to support the new data

• OS Land Cover Tier A: A high-level description of the land cover; more detail is provided in the OS Land Cover Tier B attribute​

• OS Land Cover Tier B: A detailed description of the land cover type. Up to five distinct land cover types can be applied​

• OS Land Use Tier A: A high-level description of the main activity that takes place at the location or that the feature supports​

• OS Land Use Tier B : A detailed description of the main activity that takes place at the location or that the feature supports​

Buildings styled by Land Use

Where has the new attribution come from?

Ordnance Survey surveyors and remote sensing teams have been capturing and maintaining information on land cover, land use and a more detailed level of description for over 10 years.​

• This data has then been transformed to match attribution for existing products, such as OS MasterMap Topography Layer​

• However, in the OS NGD data it is being published at the original, more granular level

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Links that may be useful:

OS NGD Documentation | OS National Geographic Databaseosngd.gitbook.io

OS Data HubOrdnanceSurvey

https://www.ordnancesurvey.co.uk/business-government/products/os-select-buildwww.ordnancesurvey.co.uk

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