Ordnance Datum Newlyn (or ODN for short), a local geoid model that defines orthometric heights in Britain, based on the mean sea level at Newlyn, Cornwall between 1915 and 1921.
Ordnance Datum Newlyn (or ODN for short), a local geoid model that defines orthometric heights in Britain, based on the mean sea level at Newlyn, Cornwall between 1915 and 1921.