OS NGD Land Use
A Lightning Talk
What are the layers in OS NGD Land Use?
The OS NGD Land Use Theme contains features that represent the geographical areas that have been identified as having a specific purpose, for example hospitals, universities, industrial parks, railway stations. It is a marked step change from OS MasterMap Sites Layer in the data that it contains. There are three feature types:
Site: This is a polygon feature that represents a recognisable extent of a particular function or activity, a few of them are mentioned above.
Site Access Location: This is a point feature that represents the geographical locations where pedestrians or vehicles can enter or leave a site.
Site Routing Point: This is another point feature that represents a location on the road network which provides entry or exit into a site for vehicles and/or pedestrians.
What formats does the OS NGD Land Use data come in?
The OS NGD Land Use 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. All of the same feature types are accessible in csv format and all the same attribution as the Geopackage, however instead of storing the geometry in a GIS ready format, ‘Site’ for example is stored as a MULTIPOLYGON attribute all of the vertices stored as co-ordinate pairs in the text file. ‘Site Access’ and ‘Site Routing’ are stored as a POINT attribute with a co-ordinate pair for each point.
What is the new attribution?
The attribution has changed from the OS MasterMap Sites product:
OS NGD data has an OSID
The features have a TOID, version date and changetype similar to the OS MasterMap family of products, although the TOID is an optional field
There is a Primary UPRN of the address record most likely to represent the same site where this can be identified unambiguously
The land use categories have been increased. The OS Land Use Tier A gives a high-level description of the main activity the site is used for. OS Land Use Tier B gives a more detailed description of the main activity, while the description gives a much more granular descriptive value intended for quickly understanding what the feature represents.
The OSID in the Site layer and the Site ID in the Site Access Location layer are the same value
The OSID the Site Routing Point layer and the Routing Point ID in the Site Access Location Layer are the same value
Source of the new attribution
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.
In the case of Land Use several classifications of Land Use have been captured but had not made it into the existing products.
This data has then been transformed and filtered to match attribution and content for existing products, such as OS MasterMap Sites Layer, however in the OS NGD data it is being published at the original, more granular level.
Currently anything in product from OSMM Greenspace and OSMM Sites is included in OS NGD Land Use. The TOID is present where there is definite match with OSMM Sites, if no match is found then the TOID will not be present.
In addition to these, Residential polygons have now been included which have been generated from an algorithm rather than from surveyor or remote sensing capture.
Coverage comparison
The OS NGD Land Use data has all the polygons that were previously in OS MasterMap Sites Layer and OS Open Greenspace – but has significantly more new polygons that have been added in.
At the time of launch of the OS NGD there are:
46,124 polygons in OS MasterMap Sites Layer
149,588 polygons in Open Greenspace
24,352,168 polygons in OS NGD Land Use
It is worth noting, as with OS MasterMap Sites Layer, these polygons do not represent a legal extent, more the extent of how the land is used. This is particularly relevant to the new Residential polygons.
Classification comparison
Alongside the increase in number of polygons is the increase in the classifications in the data.
OS MasterMap Sites Layer has 7 groups broken into 40 functions
OS Open Greenspace has 10 functions
OS NGD Land Use has 360 descriptions
For example:
OS Open Greenspace has Golf Course
OS NGD Land Use has: Golf Centre, Golf Clubhouse, Golf Course and Golf Driving Range
Why do sites appear ‘stacked’ in OS NGD Land Use?
It is possible to have multiple entries for a site for OS Land User Tier B.
An Education site in OS Land Use Tier A may have multiple Tier B land uses, for example Secondary Education and Further Education.
However, it is not possible to have stacked entries for OS Land Use Tier A for a site. So, if an Education site also contains a sports facility two polygons will exist for the same site; one for the Education site and another for Sport Attraction Or Facility.
Complete Land Use coverage
The Land Use theme does not give a complete coverage of Land Use. It has a coverage of sites by their function (health, education, residential and so on), but does not currently cover things like roads, rail and fields..
To achieve a complete coverage of features with Land Use attribution requires combining elements from: Land Use, Buildings, Land, Structures, Transport Features and Water Features
It is also of note that some of the newly added sites (such as residential) are not fully complete at launch and that work is continuing on them.
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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