[gdal-dev] Mismatched output from listgeo/gdalwarp/cs2cs

Even Rouault even.rouault at mines-paris.org
Mon Jan 9 09:40:36 EST 2012

> This leads me to conclude that without an +datum reference or a +towgs84
> parameter value proj (and possibly gdalwarp) no longer performs any
> datum transformation whatsoever. In other words it is not converting
> from one ellipsoid to the other via geocentric. Is that correct? If so,
> what is the rationale behind this choice? Our GIS toolkit takes a
> different approach and defaults to +towgs84=0,0,0 instead. My hunch is
> that this difference in default interpretation is the cause of the
> horizontal shift I'm seeing.

Yes exactly, this is the new intended behaviour of proj4. See the following
entry in the FAQ :

> Thanks in advance for any help,
> Pepijn Van Eeckhoudt

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