UK Grid Reference Widget

Provides a set of display widgets that will show the user's position as a UK Grid Reference as used on OS Maps. The widgets will display references as a 6, 8 or 10 figure grid reference.

The application implements a complex Geoid Transformation algorithm, which performs a very accurate transformation of co-ordinates from the ETRS89 system (which is used by GPS) to the OSGB36(TM) system (which is used on OS maps in the UK). The application uses a tailored polynomial interpolation of the reference data tables, and this enables transformations to be calculated to within less than 1m accuracy for the majority of UK co-ordinates.

The application also applies the transformation to the GPS Altitude, and converts it into a grid Height so that the user has an accurate height reading in the same co-ordinate space as used on the map (there can be up to 100m discrepancy between GPS and grid height depending upon location, which could cause problems to anyone attempting to use GPS altitude as a navigation aid in conjunction with a map).