OSGM15 is a National Geoid Model that converts ETRS89 ellipsoid heights to ODN orthometric heights, using a 1 km grid of geoid-ellipsoid separations.
OSGM15 is a National Geoid Model that converts ETRS89 ellipsoid heights to ODN orthometric heights, using a 1 km grid of geoid-ellipsoid separations.
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.