1:50 000 Scale Colour Raster Technical Specification
This technical specification provides detailed technical information about the 1:50 000 Scale Colour Raster. It is targeted at technical users and software developers.
The following sections contain information about 1:50 000 Scale Colour Raster, including file compression, legends, georeferencing and formats.
Product specification
Number of tiles in Great Britain
816 (edge matched)
England: 421
Scotland: 338
Wales: 86
Tile size
20 km by 20 km
Availability
National coverage
Resolution
254 and 660 dots per inch
Data structure
Raster
Transfer format
TIFF palette 8-bit (256 colours) LZW* uncompressed
TIFF palette 8-bit (256 colours) with LZW* compression
GeoTIFF with LZW* compression
Windows® BMP 8-bit colour (256 colours) uncompressed
* If LZW compressed formats are used, then registration may be required. Information is available on the Unisys® website.
Storage volumes per tile
0.3–18 Mb
Update frequency
Quarterly: March, June, September and December (change-only updates)
Product legend
Maintained versions (in English and Welsh) of the 1:50 000 Scale Colour Raster legend, which defines all of the map symbols used in the product, can be found on the 1:50 000 Scale Colour Raster Product Support page of the OS website:
Common mapping abbreviations used in the product
A full list of the common mapping abbreviations used in 1:50 000 Scale Colour Raster is available on the OS website.
Index
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