[gdal-dev] Question to ogr2ogr

[Even Rouault]

Jukka is right. You need the DHDN GK3 grid. It is mentionned on PROJ.4 wiki :
http://trac.osgeo.org/proj/wiki

The link is
http://crs.bkg.bund.de/crseu/crs/descrtrans/BeTA/de_dhdn2etrs_beta.php (no need
for ESRI installation)

The .gsb file must be copied next to the other proj.4 data files (epsg file and
other grids) (rather than GDAL data files)

Even

> Dr. Kai Behncke <behncke <at> creativista-solutions.de> writes:
>
> >
> > Dear Developers,
> >
> > I would like to know if ogr2ogr has also implemented the transformation
> > DHDN_To_ETRS_1989_8_NTv2-Transformation and if so, how it`s possible to
> use it?
> >
> > The background: I have a shape in the German Gauss Krueger Zone 4 and I
> tried to transform it with "ogr2ogr
> > -t_srs epsg:25832" to ETRS UTM 32N, but it lays always 2 meter next to the
> position where it belongs to (also
> > then, when I first tried to reproject it fist to wgs 84 and then to
> utm32N).
> >
> > then I tried it with ArcGIS and the
> DHDN_To_ETRS_1989_8_NTv2-Transformation and then it fits well....
> >
> > Thank you very much, Kai
>
> For the accurate transformations you need to have a grid shift file and you
> must tell that GDAL must use it by adding +nadgrids to the Proj4 projection
> string. I found from my computer this definition
>
> # DHDN / 3-degree Gauss zone 4 (deprecated)
> <31464> +proj=tmerc +lat_0=0 +lon_0=12 +k=1 +x_0=4500000 +y_0=0
> +datum=potsdam +units=m +no_defs  <>
>
> By looking at document
> http://support.esri.com/en/knowledgebase/techarticles/detail/18317 it looks
> that you will need a file named "BETA2007.gsb". Find and copy it from your
> ESRI installation into your GDAL data directory. Your ogr2ogr command should
> be then
>
> ogr2ogr -f "ESRI Shapefile" -s_srs "+proj=tmerc +lat_0=0 +lon_0=12 +k=1
> +x_0=4500000 +y_0=0 +datum=potsdam +nadgrids=BETA2007.gsb +units=m +no_defs"
> -t_srs epsg:25832 output.shp input.shp
>
> No guarantee that this works but have a try, it will take only couple of
> minutes. Run ogr2ogr with --debug ON and I suppose that it will tell you if
> it finds the grid shift file.
>
> -Jukka Rahkonen-
>
>
>
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