[Proj] Incorrect translations to the Gauss-Boaga system (resend)

[Markus Neteler]

On Wed, Jun 23, 2004 at 01:44:07PM +0200, Gino Lucrezi wrote:
> A few days ago I sent the following message to this mailing list, but there were no subscribers yet (except for Frank and me) so I am sending it again.
> 
> --------8<----cut-here----8<------
> I am currently using version 4.4.8 of the proj4 libraries. I mostly use them from within PostGIS, but I get the same results calling them on a stand-alone basis.
> 
> One widely used coordinate system here in Italy is Gauss-Boaga,
> corresponding to EPSG codes 26591 and 26592.
> 
> So, I often have to convert between Gauss Boaga and UTM 33 (epsg:23033)
> 
[...]
> In either case, the resulting point is about 200 metres off from the correct result.
> 
> I didn't modify the epsg file in any way.

The file does not contain datum transformation parameters for Italy.

You can fetch them from
 http://crs.bkg.bund.de/crs-eu
 -> CRS Description
   -> national European CRS
     -> Italy

or some from GRASS CVS

 http://freegis.org/cgi-bin/viewcvs.cgi/*checkout*/grass/src/libes/gis/datumtransform.table?rev=HEAD&content-type=text/plain

[...]

Regards

 Markus Neteler