[Qgis-user] reposting q on reprojection problem in QGIS > 2.0

[Peter Aldhous]

Hi all,

Apologies for reviving this thread (below), but does anyone have a
solution other than using a different data format? I ask because I will
be do some teaching using QGIS and want to work with shapefiles for that.

This is a problem that's emerged for me only with recent versions of
QGIS, so something must have changed to cause the behavior. Might it be
at the level of GDAL?

Best wishes,

Peter




-- 
Peter Aldhous, PhD
Science journalist
Contributor, MATTER <https://medium.com/matter>
phone: 415 800 3471
cell: 415 503 7323
email: peter at peteraldhous.com <mailto:peter at peteraldhous.com>
web: www.peteraldhous.com <http://www.peteraldhous.com/>
twitter: @paldhous <https://twitter.com/paldhous>

I can verify this same behavior on Win7 with QGIS 2.4 64b. I think it 
has to do with the shapes crossing the 180^(o) line. If you zoom in to 
a smaller area that includes only countries in one hemisphere, the 
borders look OK. Also, it's not only Robinson and Mollweide: any 
global projection will show strange trapezoids (even "Google" mercator)
I also see that if you use the *spatialite database file* from 
naturalearthdata.org this problem disappears. You can switch to other 
world projections with no problem.

On 29/06/2014 16:59, Peter Aldhous wrote:

> I don't think the image came through, but the problem is that every 
> polygon ends up as a trapezoid, so I end up with a collection of 
> overlapping trapezoids
>
> Peter Aldhous, PhD
> Science journalist
> Contributor, MATTER <https://www.medium.com/matter>
> phone: 415 800 3471
> cell: 415 503 7323
> email: peter at peteraldhous.com <mailto:peter at peteraldhous.com>
> web: www.peteraldhous.com <http://www.peteraldhous.com/>
> twitter: @paldhous <https://twitter.com/paldhous>
>
> On 6/29/14, 6:54 AM, Peter Aldhous wrote:
>> Hi all,
>>
>> I'm using the KyngChaos install of QGIS on the Mac (Mavericks and 
>> Lion, on different machines), and I've been having problems with  
>> projections including Robinson and Mollweide from QGIS 2.2 onwards.
>>
>> Everything was fine in QGIS 2.0, but in 2.2 and 2.4, re-projecting a 
>> world Natural Earth shapefile to a Robinson projection, for example, 
>> gives this:
>>
>>   Any idea what might be going on, and how to fix it?
>>
>> Thanks,
>>
>>
>> -- 
>> Peter Aldhous, PhD
>> Science journalist
>> Contributor, MATTER <https://www.medium.com/matter>
>> phone: 415 800 3471
>> cell: 415 503 7323
>> email: peter at peteraldhous.com <mailto:peter at peteraldhous.com>
>> web: www.peteraldhous.com <http://www.peteraldhous.com/>
>> twitter: @paldhous <https://twitter.com/paldhous>
>>

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