[Proj] proj and Dutch RD

Roger Oberholtzer roger at opq.se
Wed Jan 11 15:21:08 EST 2006

On Wed, 2006-01-11 at 21:32 +0200, Martin Vermeer wrote:
> On Wed, Jan 11, 2006 at 10:09:39AM -0800, Eric Miller wrote:
> > Here's a source listing 3-parameter values for transforming between WGS84 and RD: http://kartoweb.itc.nl/geometrics/Reference%20surfaces/DATUM.txt
> > 
> > """
> > Rijks Driehoeksmeting=Bessel 1841,-593,-26,-478,Netherlands
> > """
> > 
> > I've no idea if the signs needs to be changed or what the source is...  Caveat lector!
> > 
> > Theoretically you can use the +towgs84 argument to apply the datum transformation.
> Yes of course... you need the correct translation vector. The Bessel
> ellipsoid is non-geocentric!
> Forget my suggestion of using bessel as the 'from' ellipsoid. It should
> be wgs84 with proper shift added.

You lost me here. I thought if the GPS receiver was set to wgs84 and not
changed, the description I would use for the source long/lats (from the
receiver) would never change. I would only need to specify the various
target projections. But I find myself using one desctiption of the
source lat/longs when doing KKJ for Finland, and a different definition
of the source when doing RD projections for the Netherlands. (Not
Holland as the subject indicated.) I seem to be missing something. Or a
source of lat/longs is not as described.

> - Martin

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