[Gdal-dev] Grid based transformation with ogr2ogr

[uwe.schmitz at lverma.nrw.de]

Frank,

> Uwe,
> 
> The +towgs84 parameter will be preserved as a TOWGS84[] entry
> for the datum in WKT.  So that works fine.  In your case it would
> belong in the -s_srs since it relates the DHDN to WGS84.
> 

forgive me if I get on your nerves but...

I tried the following (this time I use GML for better reading,
with shape files I gain the same result):

ogr2ogr -f "GML" -s_srs "+init=epsg:31467 +towgs84=631,23,451" \
   -t_srs "+proj=utm +datum=WGS84 +zone=32" trf.xml org.xml

and for:
...<gml:coordinates>3396682.3999999999,5626850.4000000004</gml:coordinates>...

in org.xml I get:
...<gml:coordinates>396651.68538503139,5625036.6721786009</gml:coordinates>...

in trf.xml.

So far so good but:
cs2cs +init=epsg:31467 +towgs84=631,23,451 \
   +to +proj=utm +datum=WGS84 +zone=32<CR>
3396682.3999999999 5626850.4000000004 0.0<CR>

gives me:
396648.50       5625041.57 46.88

IMO cs2cs is correct.
What's going wrong?

Best wishes
Uwe