[gdal-dev] Warp API / gdalwarp: using projection supported by PROJ4, but not explicitly by GDAL?

Martin Lambers marlam at marlam.de
Fri Jul 13 03:26:27 PDT 2012

On Fri, 13 Jul 2012 12:01:21 +0200, Even Rouault wrote:
> > I could certainly do that, but with the '+wktext' mechanism, there
> > is no reason to add this patch anymore, is there?
> Your patch is a cleaner solution than the +wktext mechanism, which
> remains something a bit hacky (although I must admit I had never
> heard before of that QSC projection ! and it is probably some niche
> projection). The advantage of having it properly recognized is that
> you can then embed its WKT representation in a .aux.xml file and all
> tools using GDAL will be able to deal properly with it.

Yes, QSC is very limited in scope and absolutely not widely used. It is
a perfect fit for my use case (planetary-scale terrain rendering using
quadtree hierarchies for data management), but I'm not sure it is worth
adding general support for it to GDAL. For me, the '+wktext' solution
already works fine since the transformation of data to the quadtree
hierarchies is typically one way only: the resulting files are only
ever used by the renderer.

> But reading again your initial email, I didn't realize that it is not
> yet supported in proj, only proposed. So we will wait for it to be
> committed in PROJ first before committing its support in GDAL.

OK, if QSC is accepted into PROJ and full support for it in GDAL is
considered worthwhile, I can update the patch and create a ticket. 

Best regards

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