[Qgis-developer] OGRSpatialReference problem in QGIS

Frank Warmerdam warmerdam at pobox.com
Mon Aug 17 11:06:58 EDT 2009

Florian Hillen wrote:
> Hi list,
> I have a problem with OGR in Quantum GIS.
> For my Plugin which reprojects rasterdata to another CS, I need a WKT
> description of the new CS. With the QgsProjectionSelector I can select a
> CS and read out the epsg code or the proj4 string. But I fail by setting
> this to an OGRSpatialReference and export that to a WKT.
> If I transform a 4326 scene with my plugin to 31467 (german system), the
> gdal warp works correctly (the coordinates are right), but the information
> about the geocs looks like this:
> PROJCS["unnamed",PROJECTION["Transverse_Mercator"],
>     else
>     {
>         oSRS.SetProjCS((projectSelector->selectedName()).toUtf8());
>         oSRS.importFromProj4((projectSelector->selectedProj4String()).toUtf8());
>     }
> Can anyone help me with that?
> Do I have to use the C-API for that? I already had problems with the C++
> API of GDAL in Quantum GIS. My first attempt with the C-API for OGR wasn't
> successful either, that's why I asked you for a hint.


What did the Proj4String look like?  The WKT is lacking any description of
the GEOGCS which suprises me.  I'm not clear on where the proj.4 strings
in projectSelector->selectedProj4String() come from but if this string is
reasonable and has earth model information it should be reflected in the WKT.
If not, perhaps I can fix importFromProj4.

Best regards,
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent

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