On 25/01/2011 22:02, Joe Richards wrote:
The problem is my consumer GPSes (a Garmin GPSMap 60Csx and an HTC Magic running Android) thought that the equator was about 30-40m away from where a 'military GPS' had supposedly measured it and where these equatorial tricks were being performed.
There's a similar anomaly at the Greenwich Meridian in Greenwich, Kent, UK (or London, if you prefer). By international agreement, zero longitude is supposed to be the meridian passing through the center of the Airy transit circle (a telescope) at Greenwich, and a brass strip marks this line in the courtyard immediately adjacent to the transit instrument, yet a GPS receiver, set to display WGS84 co-ordinates, will not show this position as zero longitude. <http://en.wikipedia.org/wiki/Prime_Meridian#IERS_Reference_Meridian>
Whether a similar error regarding the Equator has crept into WGS84, I'm not sure. Lines of latitude are not arbitrary in the way lines of longitude are.
-- Steve _______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
