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Using OS OpenData FAQs

What mapping is included?
What are the scales of the products?
  • OS Street View = 1:10 000
  • OS Boundary Line = 1:10 000
  • OS Locator = 1:10 000
  • OS Vector Map District = 1:25 000
  • Land Form Panorama = 1:50 000
  • 1:50 000 Scale Gazetteer = 1:50 000
  • Meridian2 = 1:50 000
  • OS Strategi = 1:250 000
  • 1:250 000 Colour Scale Raster = 1:250 000
  • MiniScale = 1:1000000
What coordinate system is the data in?

The British National Grid OSGB36 is the coordinate system. The data is not available in Latitude and Longitude.

When are the updates for the products released?

The update schedules vary depending for each product.

How accurate is the data?

We try to ensure that the products released are free from errors. However, we do understand that errors can occur and we would welcome this as feedback from you.

Why are there gaps in the County layer of the Boundary Line product?

Ordnance Survey show electoral and administrative boundaries. This means that regions of Great Britain are no longer classified as a County. The Unitary Authority layers will provide the boundaries for these regions.

What formats are there?

The products are in Raster and Vector formats.

In raster data the entire area of the map is subdivided into a grid of tiny cells. A value is stored in each of these cells to represent the nature of whatever is present at the corresponding location on the ground. Raster data can be thought of as a matrix of values.

The major use of raster data involves storing map information as digital images, in which the cell values relate to the pixel colours of the image. In the example above the data records the colour of the feature which occupies that part of the map surface; the values recorded in the cells are either white, blue or red.

To reproduce the image the computer reads each of these cell values one by one and applies them to the pixels on the screen.

In vector data the features are recorded one by one, with shape being defined by the numerical values of the pairs of XY coordinates. A point is defined by a single pair of coordinate values. A line is defined by a sequence of coordinate pairs defining the points through which the line is drawn. An area is defined in a similar way, only with the first and last points joined to make a complete enclosure.

Vector data can be thought of as a list of values.

For more information on GIS files including Raster and Vector see http://www.ordnancesurvey.co.uk/oswebsite/gisfiles/d01100.pdf

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