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
