[Proj] UTM ED50 to ETRS89 datum shift problem

[karel cech]

On 12/4/06, Oscar van Vlijmen <ovv at hetnet.nl> wrote:
> > From: "karel cech"
> > Date: Mon, 4 Dec 2006 13:20:37 +0100
> > Subject: [Proj] UTM ED50 to ETRS89 datum shift problem
> >
> > Hi list,
> > I have a problem with changing datum with cs2cs using 7 parameter
> > shift from ED50/UTM30 to ETRS89. The result differs a lot from
> > transformation results made by Carthographic Institute of Valencia
> > (they work with ESRI and ERMapper)
> > My test point has following coordinates (ED50/UTM30, EPSG:23030)
> > 720931.9
> > 4376574.85
> > What I would like to obtain is aproximatly this (ETRS89, EPSG:25830):
> > 720821.51
> > 4376365.31
> > However, cs2cs gives me
> > 720748.93
> > 4376357.47
> >
> > The 7 parameters are defined by spanish institutions.
> >
> > The debug output from cs2cs (proj 4.4.9.):
> >
> > cs2cs -v +proj=utm +zone=30 +ellps=intl
> > +towgs84=-131.0320,-100.2510,-163.3540,1.2438,0.0195,1.1436,9.3900
> > +units=m +to +proj=utm +ellps=GRS80 +zone=30 +units=m -r <<EOF
>
> ....
>
> It is possible that your transformation parameters were for the coordinate
> frame rotation model. If I negate the rotation angles to force them to
> position vector rotations, I get with my stuff:
> x=720821.512; y=4376365.309
> which seems to be spot on.
> So, try:
> +towgs84=-131.0320,-100.2510,-163.3540,-1.2438,-0.0195,-1.1436,9.3900
>

Definitely.
Thanks Oscar and Jose,
Best Regards, Karel