Raster Specification

The following chapters include information about OS VectorMap District raster, file compression, symbology, georeferencing and formats.

Specification

• Data Source: Derived data

• Number of tiles in Great Britain: 2863 (edgematched)

• Tile size: 10 km x 10 km

Because digital maps frequently cover very large areas they are split down into squares known as tiles, each of which covers part of an overall area.

• Availability: National, country and tile supply available

• Resolution: 254 dots per inch

• Data structure: Raster

• Data Specification: Selection of map features combined

• Colour Palette: 256 fixed colours

• Transfer format: TIFF 8-bit LZW* compressed

• Storage Volume per tile: Compressed: approx. 6.7mb

• Greyscale: A high-quality alternative to colour raster data is to use a GIS to convert data to a greyscale format.

*If LZW compressed formats are used then registration may be required.

OS VectorMap District is supplied in the following raster formats: TIFF 8-bit LZW compressed (6.7 mb)