Property Surveys, Coordinate Systems in Great Britain

Converting Latitude and Longitude to British National Grid in C#

Converting Latitude and Longitude to British National grid


A guide to coordinate systems in Great Britain
Coordinate systems used in Great Britain


Useful Links
Wikipedia overview of the OS national grid
JavaScript datum conversions (WGS84, GRS80, Airy1830, AiryModified, Intl1924, Bessel1841)
JavaScript conversions (Lat/Long and OS Grid Reference). Good background explanations. Interesting that it provides the centres of OSGB squares when parsing grid references and not the SW corner. This will give very different results when using squares other then 1m (two letters and five digits) then my assumption. Some investigation is needed to see how everyone else handles this.
Airy1830 (OSGB) <-> WGS84 conversions
Updated composer version PHPcoord
Easting/Northing to Lat/Long (OSGB36 <-> Airy1830)
Convert between latitude/longitude, Universal Transverse Mercator (UTM) and Ordnance Survey (OSGB)
Neat collection of tools.
6-digit references identify 100m grid squares; 8 digits identify 10m grid squares, and 10 digits identify 1m squares. TG51401317 represents a 10m box with its (south-west) origin 51.40km across, 13.17km up within the TG square.
This page has a great visualisation of what a datum is, and how ellipsoids relate to each other. Without going into any of the maths, it simply shows you what it looks like, and that gives a deeper understanding of what the maths needs to achieve. This library does not have any datum conversions built in yet, but it does need it – the Airy datum on its own is a but of an island when every system under the sun uses WGS84 as its reference datum. Using this library to locate points on the map will disagree with Google Maps, for example, by hundreds of metres in many places without the conversion. Quote from this page: “A datum is a reference ellipsoid together with an offset from the center of the Earth”. Nowhere else is this eplained in such plain English.