[gdal-dev] ogr2ogr using grid shift files

[Andre Joost]

Am 07.03.18 um 11:50 schrieb Michael Schulz:
> Dear devs,
>
> why is og2ogr using a grid shift file explicitely specified in the
> proj4 string in the s_srs parameter and not when the same proj4 string is
> in the system-wide proj4/epsg file?
>
> This example gives correct projected results:
>
> ogr2ogr -f 'ESRI Shapefile' target.shp -s_srs "+proj=tmerc +lat_0=0
> +lon_0=9 +k=1 +x_0=3500000 +y_0=0 +ellps=bessel
> +nadgrids=@BWTA2017.gsb,BETA2007.gsb +units=m +wktext" -t_srs "EPSG:25832"
> source.shp
>
> The proj4/epsg contains exactly the same definition for EPSG:31467, but
> when used like this:
>
> ogr2ogr -f 'ESRI Shapefile' target.shp -s_srs "EPSG:31467" -t_srs
> "EPSG:25832" source.shp
>
> the transformation is using the towgs84 parameters defined in
> datum_shifts.csv...
>
> Is this the intended behaviour?
>

Yes, this is intended. GDAL has its own CRS definition files, and does 
normally not fall back to the proj4 folder definitions.

C:\OSGeo4W64\share\gdal\datum_shift.csv is the file to look for, 
containg a definition for EPSG:4314 DHDN, which will be used for all 
DHDN based projected CRS.

So try to adjust that file.

HTH,
Andre Joost