1:25 000 Scale Colour Raster: technical information and specifications

Sample data
User guide
Updated tiles
Frequently asked questions

Specification	1:25 000 Scale Colour Raster
Coverage	Great Britain (England, Scotland and Wales)
Availability	Order by: national extent (GB). country extent: (England, Scotland and Wales). individual tile. user defined area. specific tile identities; or administrative region. Tiles are supplied whole and not clipped.
Data source	Explorer production data.
Data structure	Raster.
Scale	Nominal scale is 1:25 000. Recommended minimum to maximum scale range for viewing is 1:8000 to 1:25 000 scale.
Transfer format	TIFF 8 bit LZW compressed TIFF packbit compressed
Colour Options	Colour 1:25 000 Scale Colour Raster data consists of a palette of 256 colours. A high-quality alternative to black and white raster data is to use a Geographical Information System (GIS) to convert the colour data to a greyscale format.
Storage volume per tile	Compressed: 1.5 Mb –3 Mb
Tile size	10 km by 10 km
Number of tiles in Great Britain	Great Britain = 2 864 (edgematched) England: 1 508 Wales: 289 Scotland: 1 132
Supply media	CD and DVD
Resolution	254 dots per inch = 100 dots per cm
Update frequency	Change only update every six months after initial supply. Usually issued in May and November. Re-supply is available on request but may attract an additional charge.
Styling	A legend is available as a downloadable PDF file. View or download a PDF version of the legend (1Mb)
Geo-reference files	To locate 1:25 000 Scale Colour Raster data tiles in their correct geographical position in a GIS they need to be 'georeferenced'. More information and download the files
Coordinate Reference System	British National Grid (OSGB36).

User guide

The user guide contains information on the technical specification and product specification for 1:25 000 Scale Colour Raster to help you understand how to use the data.

View or download a PDF version of the user guide (2.4 Mb)

Updated tiles

1:25 000 Scale Colour Raster is updated in May and November each year.

View a Microsoft® Excel list of all tiles in the latest (November 2009) update (42Kb)

View a Microsoft® Excel list of all tiles and their date of update (181Kb)

Frequently asked questions

Can I define my own area?

Yes, it is possible to order user defined areas by;
* specific tile identities;
* administrative region; or
* bounding box.

The product is also available by;
* Great Britain
* England
* Scotland
* Wales

Although Tiles are supplied whole and not clipped to fit geographic areas.

Does Ordnance Survey provide a list of updated tiles?

Ordnance Survey provides a list of tiles that were updated for that release on the product Technical Information page. The product is updated every May and November

When were my tiles last updated?

Ordnance Survey provides a list of every tile depicting the date they were last updated on the Technical Information page for the product.

Can I georeference the data file?

To locate 1:25 000 Scale Colour Raster data tiles in their correct geographical position in a GIS they need to be 'georeferenced'. Refer to the Technical Information or follow the link below about geo-referencing.

http://www.ordnancesurvey.co.uk/oswebsite/products/georeferencing/aboutpopup.html

Can I convert it into a monochrome image?

It depends on which software package you are using. Some packages have a facility whereby you can load the colour image onto a computer and, using one of the command drop-down menus, select the greyscale option. This will change the colours on an image to shades of grey (greyscale). This is not the same output as monochrome where features in the file are either black or white.

Does Ordnance Survey provide a Legend or symbols guide?

A legend is available to download as a PDF via the Technical Information pages for this product