I was speaking in terms of the user. The point I was trying to make is that if the user had a map, chart or simply a set of three dimensional coordinates created from one datum, then that user had better use the same datum or position errors will be evident. The Z direction is typically used by navigators to indicate vertical direction, an example of this is when using the north, east, down (NED) references in an inertial reference frame.
Michael On Wed, Sep 14, 2011 at 2:59 PM, Magnus Danielson < mag...@rubidium.dyndns.org> wrote: > Michael, > > On 14/09/11 17:05, Michael Perrett wrote: > >> The user, mostly military or marine, would choose the datum he/she wanted >> to >> use. This would match up the local map with the GPS derived position. The >> difference could be quite large (hundreds of feet), especially important >> in >> the Z (vertical) direction! >> > > In GPS, the Z axis is not the vertical axis... X, Y and Z is the receivers > position in meters according to GPS/WGS84 which is then translated into > long, lat and height. > > Cheers, > Magnus > > ______________________________**_________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/** > mailman/listinfo/time-nuts<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts> > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
