[mapserver-users] WMS Overlay shift

[Frank Broniewski]

Thanks for the answers,

finally I found the reason. I had an additional towgs parameter set in the 
layers projection block. Don't remember why I put it there, but it was causing 
the shift. I am using init=epsg:2169 as projection definition now as the only 
projection definition in the maps projection block and things are in place.

On Friday 05 June 2009 11:09:08 Milo van der Linden wrote:
> Hello Frank,
>
> The shift probably has to do with the reference ellipsoid, If it is not
> defined explicitly in the projection BUT is different from wgs84 you
> should define the towgs parameter.
>
> You can check out a mail discussion describing a wgs84 ellipsoid shift
> issue here:
> http://postgis.refractions.net/pipermail/postgis-users/2006-October/013571.
>html
>
> perhaps it will clear things.
>
> You can also check out map projections used in germany in more detail here:
> http://www.mapref.org/MapProjectionsDE.html
>
> It may also help if you post your proj4 string or the EPSG code you use
> so we can see the difference.
>
> Frank Broniewski wrote:
> > Hello list,
> >
> > I am debugging a problem with my WMS server. I am serving
> > administrational boundaries in a national reference system for use in
> > different applications.
> >
> > Just yesterday I noticed a shift of the WMS layer to the east when I
> > overlay the WMS layer with the original shapefile in ArcGIS. The shift is
> > approx. 29m and I have no clue where to start looking for a solution.
> >
> > There is only one projection in the mapfile, and I set the view in ArcGis
> > to the same projection. I checked the projection definition in ArcGis
> > already to see if there is some mismatch but I couldn't find any. So I am
> > rather clueless where to start looking for the reason of the shift.
> >
> > I checked also in OpenJump to see wether this is an ESRI effect, but
> > there is the same shift in OpenJump
> >
> > Any hints are welcome ...
> >
> > Frank
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