Geodesy and positioning

Information and tools related to Ordnance Survey’s geodetic and positioning activities

What is geodesy and positioning?

Geodesy is the science of measuring the shape of the Earth. It is a fundamental input to Ordnance Survey’s public task to “maintain and develop the underlying physical infrastructure which is needed to support the capture and maintenance of the National Geographic Database”.

Geodesy and positioning at Ordnance Survey includes:

  • The national GNSS Network OS Net® realising a frame of the European Terrestrial Reference System 1989 (ETRS89) coordinate reference system.
  • OS Net data and products to provide user access to ETRS89.
  • The national transformation OSTN15™ to define and provide user access to the OSGB36® mapping coordinate reference system via ETRS89.
  • The Fundamental Bench Mark (FBM) network to define Ordnance Datum Newlyn (ODN) on mainland GB.
  • The national height corrector surface (“geoid model”) OSGM15™ to realise and provide user access to ODN and other height datums (e.g. on some Scottish islands) via ETRS89.

OS positioning tools and resources

  • OS Net data

    Discover OS Net; our highly accurate and resilient network of Global Navigation Satellite System (GNSS) base stations across Great Britain.

  • Coordinate transformations

    View our full suite of GNSS coordinate transformation tools, software and resources.

  • Legacy control data

    Search for legacy data such as passive stations, benchmarks, or triangulation stations.

Geodesy and positioning service policy

Read Ordnance Survey’s geodetic and positioning services policy, activity plans and strategic aims for future work and consultations.

View the service policy