[gdal-dev] Support for QSC in GDAL (was: Warp API / gdalwarp: using projection supported by PROJ4, but not explicitly by GDAL?)

Even Rouault even.rouault at spatialys.com
Mon Nov 10 10:39:47 PST 2014

Le lundi 10 novembre 2014 18:37:53, Jed O. Kaplan a écrit :
> Dear GDAL developers,
> I would like to resurrect this thread from a couple of years ago regarding
> GDAL support for the Quadrilateralized Spherical Cube (QSC) projection in
> Now that the QSC projection is supported by proj4 and works well, would it
> be possible to have the projection fully supported in GDAL, i.e.,
> identifiable in a WKT string?
> The QSC projection has many potential uses whenever working with global
> data and would be a valuable additional feature for GDAL.


I've committed Martin Lambers' patch from 13/07/2012 with the modification I 
suggested, i.e. add _ instead of space in  #define SRS_PT_QSC              


> Thanks in advance for your help!
> Best regards,
> Jed Kaplan
> 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
> Martin
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