[Proj] Antw: RE: Winkel Tripel Problems

Lars Pennig l.pennig at klett.de
Thu May 10 03:16:51 EST 2012

Great advice!

But what shall I do if I have users who are not familiar with GRASS
etc. and only want to do a forward projection into Winkel Tripel. Is
there any chance that foward and inverse projections are one day
included in proj? Or maybe should I hire a programmer to do so?


>>> Mikael Rittri <Mikael.Rittri at carmenta.com> schrieb am Donnerstag,
10. Mai 2012
um 09:02 in Nachricht
<E4AB3DD44D22854B819908379DE4AD49391C47A2 at SETHNWS023.carmenta.se>:
> Lars wrote:
>> ... I wonder why Winkel Tripel is not supported.
> Probably because Proj.4 supports only the forward direction
> (from Long/Lat to projected coordinates).
>>proj +proj=wintri -I
> Rel. 4.8.0, 6 March 2012
> <proj>:
> inverse projection not available
> program abnormally terminated
> You might think that you only wanted the forward direction, but
> for many purposes both directions are needed. I don't know about
> QGIS, but maybe they decided to ignore Winkel Tripel completely. 
> Some years ago, Oscar van Vlijmen gave a link to a paper that
> that described how to invert Winkel Tripel.
>    http://lists.maptools.org/pipermail/proj/2007-May/002964.html 
> Another version of the paper was published in the CaGIS journal,
> see 
> Best regards,
> Mikael Rittri
> Carmenta
> Sweden
> http://www.carmenta.com 
> -----Original Message-----
> From: proj-bounces at lists.maptools.org
[mailto:proj-bounces at lists.maptools.org] 
> On Behalf Of Lars Pennig
> Sent: den 9 maj 2012 16:19
> To: proj at lists.maptools.org 
> Subject: [Proj] Winkel Tripel Problems
> Hi all,
> since I'm working with QGIS (which relies on proj) I wonder why
> Tripel is not supported. I understand that Winkel Tripel is
> in proj (+proj=wintri) but that seems not to work. For Example,
> a user projection with +proj=wintri within qgis and then trying to
> project (on the fly) a dataset of epsg:4326 (plate carree) to this
> projection fails. Instead qgis shows the existing dataset in
> Anyone out there with a solution?
> Thanks in advance, Lars
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