OS Net is a critical component of the infrastructure for realising our national coordinate systems in Great Britain.
The national coordinate systems we use are ETRS89, OSGB36 National Grid, and Ordnance Datum Newlyn (ODN):
- ETRS89 is the standard coordinate system for precise GNSS positioning throughout Europe. It is a precise, time (01-01-1989) fixed and region (Europe) fixed version of the WGS84 coordinate system.
- OSGB36 National Grid is the national standard coordinate system for topographic mapping, including all OS mapping.
- ODN is the national standard coordinate system for measuring height above mean sea level. ODN is the usual definition of mean sea level in mapping and engineering in mainland Great Britain. Outlying islands such as Shetland, Outer Hebrides, Orkney, Isle of Man and the Scilly Isles have their own versions of ODN.
OS Net makes the accurate determination of these national standard coordinates much easier and more efficient for land surveyors, compared to traditional (pre-GNSS) surveying methods. It is now possible to determine precise ETRS89 coordinates for your GNSS control stations with a single GNSS receiver, without ever leaving the survey site.
These coordinates can be instantly and precisely transformed to OSGB36, National Grid and ODN height coordinates. Therefore, a greater range of mapping, engineering and environmental projects can now use precise national coordinates than was ever possible before.