# Product details ## Features 1:250 000 Scale Colour Raster shows cities, towns, many villages, motorways, A and B roads, railways, rivers, and some woodlands across Great Britain. ## Source and scale 1:250 000 Scale Colour Raster is derived from the 1:250 000 scale topographical digital database. It is designed to be nominally viewed at a 1:200 000 scale. ## Coordinate reference system 1:250 000 Scale Colour Raster is available in British National Grid coordinates, which are expressed in metres relative to an origin set to a point west of the Isles of Scilly. These coordinates can easily be spatially related to other surveys, drawings, datasets, and Ordnance Survey products. ## Coverage Coverage of 1:250 000 Scale Colour Raster is all of Great Britain. It is supplied in 100km by 100km tiles aligned to the National Grid. Where a line feature ends by intersecting the tile edge, it is matched with its corresponding feature on the adjacent tile so that both features end on the same unique coordinate. The representation of detail across the tile edge is of a cartographically acceptable standard when plotted or displayed at scale. ## Product revision programme 1:250 000 Scale Colour Raster is updated via a continuous revision programme. The revision programme tracks real-world change, and is determined by assessing the following factors: * Known surveyed change. * Change intelligence gathered from a range of sources. * How long it has been since an area was last revised. Priority is given to prestige sites categorised as significant items of change, such as major road construction projects. Significant items of surveyed change relevant to the scale are captured during the revision programme. ## Resolution Each data tile is converted into a raster tile at a resolution of 10 dots per millimetre (dpmm)/254 dots per inch (dpi). One pixel represents 25 metres on the ground. This resolution maintains the necessary clarity of text. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.os.uk/os-downloads/products/maps-and-imagery-portfolio/1-250-000-scale-colour-raster/1-250-000-scale-colour-raster-overview/product-details.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.