This document contains additional theoretical information related to OS VectorMap District. All users will find the Product Information document useful and informative.
OS VectorMap District is a free mapping dataset designed for providing contextual mapping output on paper, PCs, hand-held devices, or the Internet. Available as pre-styled static images (Raster data) and points, lines, and polygons (Vector data). The vector format of the product consists of layers to enable you to customise and style output to suit your needs.
OS VectorMap District has been improved to offer enhanced functionality as well as offering greater consistency with other OS products, including OS Open Map – Local.
The product now offers significantly improved generalisation, resulting in a more attractive map that compliments the more detailed street-level OS VectorMap® Local product.
The key features of OS VectorMap District product are:
Provides a clear visual backdrop map that can be easily styled to meet specific needs.
Please refer to the Product Cartographic Stylesheets webpage for styling options: os.uk/resources/carto-design/cartographic-stylesheets.html
Offers flexibility to user through ease of use to control content display.
Suitable for varying scenarios around the mid-range scale of 1:25 000
Analyse data in relation to important public buildings, roads, railways, lines and more
Compatible with other open datasets available from data.gov.uk and many other sources.
The purpose of OS VectorMap District data is to support a wide range of customer applications that utilise geographic information. These may include:
Backdrop mapping on your website
For your area, you may wish to take advantage of free data on the Government’s data.gov.uk website, for example, air pollution data. The layered structure of OS VectorMap District enables you to display the map to show only the features you want to show – for example, roads, place names and buildings.
You may want to style the data as a faded map backdrop to ensure your own or third-party overlaid data are clearly portrayed. For example, backdrop mapping can be used by public sector organisations to share information with the public. Such applications include providing the location of GP surgeries or dentists to the public, or the performance of schools based on exam results in a district.
Develop an interactive web application
OS VectorMap District has been designed for on-screen use, with generalised detail and an appropriate level of content that gives an uncluttered appearance. Subscribers to the OS OpenSpace® application programming interface (API) can build location-based services using the map to guide smartphone users and provide location-specific information.
Display your business location
Do you want to tell your customers how to get to your business? The district view of OS VectorMap District is ideal for creating a map of a suburban area or part of a city, complete with locality names for context.
Your customers can then zoom in to your business at a street level using the OS VectorMap District product.
OS VectorMap District topographic features are generalised representations of real-world objects, including buildings, roads, railways, and rivers. The data also includes non-topographic features such as administrative and electoral boundaries (GML and Shapefile format only), cartographic text and symbols.
The detail within OS VectorMap District has been generalised from Ordnance Survey large-scale data. Map generalisation is the process of reducing the scale and complexity of map detail whilst maintaining the important elements and characteristics of the location.
Map generalisation comprises of the following processes:
Selection/omission: some features that appear at larger scales are not selected at the smaller scales. For example, in the public amenities layer individual features in close proximity can be grouped to a single point.
Simplification: simplification can take a number of forms in OS VectorMap District. It can be line simplification, for example, in a vector product; a very winding stream could have the number of data points that represent it reduced.
Exaggeration: features that are small but are too important to a particular landscape to be omitted are enlarged. For example, some isolated rural buildings are often enlarged to a minimum size rather than being omitted.
Aggregation: aggregation is the combining of a number of small features to make a larger one, such as buildings.
Symbolisation: features that are shown in detail in other OS products, such as OS VectorMap Local may be shown by standard symbolisation in OS VectorMap District. For example, railway stations are depicted as point symbols.
Displacement: the movement of the representation of a feature away from its ground position in order to maintain its prominence. There is very little displacement in OS VectorMap District, but in certain circumstances, some features may be moved away from adjacent detail if their representation would otherwise be lost; for example, some buildings are moved away from road edges to ensure they remain prominent.
The following is a description of the features that are available in the product. A full list of feature classes and their associated attributes is given in the .
Not all features available in the product are included in the raster format. For a full list of features and their styling in the raster format please refer to the legends in the .
The GML naming of attributes is used in the main text of this guide; the naming of the attributes in shape files will be different due to the limitations of the shape file format.
A built entity that includes a roof. This is a generalised building and could be made up of an amalgamation of other buildings and structures.
Shapefile: Building.shp
A building constructed largely of glass for the purposes of commercial horticulture. This is a generalised glasshouse and could be made up of an amalgamation of individual glasshouses. Only glasshouses larger than 5000 m2 are included.
Shapefile: Glasshouse.shp
GML FeatureType: Glasshouse
A road is defined as a metalled way for vehicles. A vehicle is defined as one with wheels on both sides of its body. Metalling is defined as any artificial (man-made) surface including areas of asphalt, concrete and gravel. Roads that form part of the public network and driveways to private properties that are over 100 m in length are captured. Dual carriageways are represented by centrelines when the two carriageways are closer than 32.5 m, roundabouts are represented by points when smaller than 450 m2, dead ends are removed when shorter than 36 m and roads are simplified with a 4 m tolerance.
Road alignments will have one of the following 13 classifications, each of which can be separately identified by the
‘classification’ attribute:
‘Motorway’
‘Primary Road’
‘A Road’
‘B Road’
‘Minor Road’
‘Pedestrianised Street’
‘Local Street’
‘Private Road Publicly Accessible’
‘Motorway, Collapsed Dual Carriageway’
‘Primary Road, Collapsed Dual Carriageway’
‘A Road, Collapsed Dual Carriageway’
‘B Road, Collapsed Dual Carriageway’
‘Minor Road, Collapsed Dual Carriageway’ Shapefile: Road.shp
GML FeatureType: Road
Roundabouts smaller than 450m2 are represented as point features, and the roads are extended to meet at the centre point. Mini roundabouts are not included.
Shapefile: Roundabout.shp
GML FeatureType: Roundabout
See the Technical specification for full list of roundabout ‘classification’ attribute values.
Road tunnels are represented as approximate centrelines of the road that runs through the tunnel.
Shapefile: RoadTunnel.shp
GML FeatureType: RoadTunnel Differences between vector and raster formats:
A selection of road names and numbers are shown in the raster product, where space permits.
Point feature representing the approximate location of numbered junction on a motorway.
Shapefile: MotorwayJunction.shp
GML FeatureType: MotorwayJunction
An inland waterway body sufficiently wide enough to capture as an area feature. Small lakes and small islands in waterbodies are not included.
Shapefiles: SurfaceWater_Line.shp, SurfaceWater_Area.shp
GML FeatureTypes: SurfaceWater_Line, SurfaceWater_Area
In England and Wales these tide lines will be the levels of mean tides, for example, of a tide between a spring and neap tide. In Scotland the tide lines are those of mean spring tides. In places where there is no Foreshore (for example vertical cliffs), the TidalBoundary is classified as 'High Water Mark'.
Shapefile: TidalBoundary.shp
GML FeatureType: TidalBoundary
Polygons defining the extents of tidal water, up to the High Water Mark defined by the TidalBoundaries and the Normal Tidal Limit of rivers. Tidal water is not included under bridges.
Shapefile: TidalWater.shp
GML FeatureType: TidalWater
The part of the shore or beach which lies between the Low Water Mark and High Water Mark defined by the TidalBoundaries. The same condition may exist in non-contiguous off-shore areas.
Shapefile: Foreshore.shp
GML FeatureType: Foreshore
A line feature representing the limit of a government administrative area. In the event that a boundary represents the limit of more than one administrative area, classifications are applied in hierarchical order, with priority given to the largest containing area. An exception is made for National boundaries, which will be coincident with the underlying local government boundary.
The attribute ‘classification’ defines the type of boundary:
‘National’
‘District Or London Borough’
‘County Or Region Or Island’
‘Parish Or Community’
Shapefile: AdministrativeBoundary.shp
GML FeatureType: AdministrativeBoundary Differences between vector and raster formats:
In the raster product only the national boundaries are depicted.
All railways are represented as lines and are broken where they pass under bridges, buildings or other obstructing detail. Railway sidings and the tracks of travelling structures are not included. The attribute ‘classification’ defines the type of railway:
‘Multi Track’
‘Single Track’
‘Narrow Gauge’
Shapefile: RailwayTrack.shp
GML FeatureType: RailwayTrack
Railway tunnels are represented as approximate centrelines of the railway that runs through the tunnel.
Shapefile: RailwayTunnel.shp
GML FeatureType: RailwayTunnel
Point feature representing the buildings and platforms by a railway line where a train may stop to pick-up or drop-off goods or passengers. The attribute ‘classification’ defines the type of station:
‘Light Rapid Transit Station’
‘Railway Station’
‘London Underground Station’
‘Railway Station and London Underground Station’
‘Light Rapid Transit Station and Railway Station’
‘Light Rapid Transit Station and London Underground Station’
The name of the station is held in the attribute ‘DISTNAME’ in Shape and distinctiveName in GML.
The position of the railway station will be close to a railway alignment but will not necessarily be coincident with it.
Shapefile: RailwayStation.shp
GML FeatureType: RailwayStation
A point feature that represents the location of certain types of function or activity with appropriate attribution. The classifications are:
Air Transport
Education Facility - School
Education Facility - Higher
Medical Care
Road Transport
Road Services
Water Transport
Place Of Worship
Leisure Centre
Police Station
Please note:
Only available in the vector product, functional sites include features previously supplied as ‘PublicAmenity’ and ‘Airport’ features. In previous product releases a cartographic selection was applied to these features, which is now replaced with a complete supplied set.
Some functional sites may contain multiple sites (points) such as Educational Facility where they may have both Educational Facility – School and Educational Facility – Higher.
Shapefile: FunctionalSite.shp
GML FeatureType: FunctionalSite
Areas of trees; coniferous, non-coniferous and mixed are represented as polygons. Small areas of woodland are omitted and small clearings in woodland are filled.
Shapefile: Woodland.shp
GML FeatureType: Woodland
Ornament features are facsimiles of artwork, represented as a polygon, these were originally drawn on paper maps to depict coastal rocks, outcropping rocks, cartographic slopes and scree.
Shapefile: Ornament.shp
GML FeatureType: Ornament
Cables used to supply electricity that is suspended between pylons.
Shapefile: ElectricityTransmissionLine.shp
GML FeatureType: ElectricityTransmissionLine
A representative point feature giving the general location of a settlement name or geographic place name, for the purposes of text placement.
GML supports all the characters in the Welsh language and all names are stored in the ‘distinctiveName’ attribute. Legacy formats such as shapefile, do not support the full Welsh alphabet, therefore an alternative is provided using either the ‘DISTNAME’ or ‘HTMLNAME’ attributes.
When using the OS VectorMap District shapefile NamedPlace.shp:
If labelling using the DISTNAME attribute, accents appear on vowels, but the Welsh consonants will have their circumflexes removed: W, w, Y, y.
If labelling using the HTMLNAME attribute, the accents on vowels will be the same, but the Welsh consonants will be encoded using HTML escape characters, which will display correctly when displayed using software that can interpret these characters (Ŵ,ŵ,Ŷ,ŷ).
fontHeight: the suggested height of the font is Small, Medium, Large and Extra Large
textOrientation: the orientation of the text string in degrees clockwise from horizontal. It is held as a number between -90 and 90. This is named ORIENTATIO in Shape and textOrientation in GML
Shapefile: NamedPlace.shp
GML FeatureType: NamedPlace
Point feature which in most cases represents the location of a summit of a hill or mountain, together with an elevation measurement.
Shapefile: SpotHeight.shp
GML FeatureType: SpotHeight
The vector product formats provide for the use of a variety of coordinate reference systems. At present, only the British National Grid (BNG) is used in OS VectorMap District. The BNG spatial reference system uses the OSGB36® geodetic datum and a single Transverse Mercator projection for the whole of Great Britain. Positions on this projection are described using easting and northing coordinates in units of metres.
The BNG is a horizontal spatial reference system only; it does not include a vertical (height) reference system. In OS VectorMap District, heights are given by the ‘height’ attribute in the ‘SpotHeight’ feature. The geometric attributes therefore contain horizontal geometry only.
OS VectorMap District is derived from large-scale data, copyright 2017.
During production many checks are undertaken to ensure that data supplied to customers are both accurate and complete. During digital manipulation in creating the data, all sources of that data are checked for conformance to specification.
These quality control checks take the form of:
visual checks by operators;
data testing against the product specification; and
testing is carried out on a selection of tiles from a full national set.
Coordinates have a precision of 1 cm and are stored to two decimal places of a metre.
It is the flexibility to select and style the different feature classes in different ways that makes the vector format of OS VectorMap District such a versatile contextual mapping product. It can be flexibly styled in a wide variety of ways to best provide a geographic context to the customer’s overlay information.
The raster version is ready-styled as backdrop and full colour and these styles are fixed within the limitations of the image viewing software. Below is an example of both the raster styles. The full graphic legends are available online here.
OS VectorMap District is available as:
Vector: ESRI Shapefile with each tile dataset zipped using gzip.
Raster: TIFF and compressed using LZW (Lemple-Ziv-Welch) compression.
Data: GML v3.2. Simple Features and schema zipped as a single file using gzip.
OS VectorMap District can be ordered from the Ordnance Survey OS OpenData™ website. This allows you to order your area of choice and format.
Data is available on DVD or as a download from: os.uk/oswebsite/products/vectormap/district/index.html
Ordnance Survey divides Great Britain into squares 100 km by 100 km. Each of these squares has a unique two-letter reference, for example, TG in the diagram below.
OS VectorMap District vector format tiles are identified by quoting the National Grid reference of the south-west corner of the 100 km² area they cover, for example TG.
To describe an OS VectorMap District raster format tile, which covers 10 km by 10 km, first add a two-digit reference to the 100 km by 100 km square reference, with the easting first followed by the northing, for example, TG23. For additional information on how to use the National Grid, visit the Ordnance Survey website at: os.uk/support/the-national-grid.html
Coverage is England, Wales and Scotland.
55 tiles, each covering 100 km x 100 km comprise the national set.
Each tile comprises a set of up to 24 Shapefiles.
Each Shapefile holds a single feature type.
Features within each Shapefile are cut into a 10 km x 10 km grid.
Tile sizes range from 1 Mb to 697 zipped Mb.
The data is not encrypted.
55 tiles, each covering 100 km x 100 km comprise the national set.
Each 100 km tile is split into 20 km by 20 km tiles (809 in total).
Each tile comprises of up to 57 Feature Codes.
Features that cross the grid line are split.
Tile sizes range from 1 Mb to 347 Mb.
The data is not encrypted.
2863 tiles, each covering 10 km x 10 km comprise the national set.
Tiles range from 2 Mb to 6.7 Mb.
In the vector product features that cross tile edges are included in both tiles, represented as hairy tiles. This avoids the creation of invalid geometries by arbitrary cutting, and facilitates greater use of the data in analytical applications. All features have unique identifiers which can be used to remove duplicates across tile edges, if required.
Note that these identifiers will not be persisted or maintained between product releases.
