[Qgis-user] Problems with re-projection in QGIS>2.2 on MacOS

[Larry Shaffer]

Hi Peter,

On Sun, Jun 29, 2014 at 9:35 AM, Peter Aldhous <peter at peteraldhous.com>
wrote:

>  Yes, on my system the problem also resolves on zooming - although I'd
> only use Robinson for a global view.
>
> However, I have no problem with Google Mercator.
>
> Would really like to know how to fix this!
>

Try turning off 'Simplify geometry' for the layer (in layer properties)
[0]. For new projects, not existing ones, the default behavior in QGIS 2.4
can now be controlled by a checkbox in Options -> Rendering (I think it's
the Rendering tab, not at a computer right now). Then, you can selectively
turn it on for layers where simplification would help speed up rendering.

[0] http://gis.stackexchange.com/a/100333/6725

Regards,

Larry Shaffer
Dakota Cartography
Black Hills, South Dakota



>
> 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
> web: www.peteraldhous.com
> twitter: @paldhous <https://twitter.com/paldhous>
>
>  On 6/29/14, 7:57 AM, Micha Silver wrote:
>
> I can verify this same behavior on Win7 with QGIS 2.4 64b. I think it has
> to do with the shapes crossing the 180º 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
> web: 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
> web: www.peteraldhous.com
> twitter: @paldhous <https://twitter.com/paldhous>
>
>
>
>
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>
> --
> Micha Silver
> GIS Consulting
> 052-3665918http://www.surfaces.co.il
>
>
>
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