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- > > > > _______________________________________________ > gdal-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/gdal-dev > _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
