[Qgis-user] QGIS reprojection broken?

[Brent Wood]

Hi Nyall,


I should have mentioned I'm using v2.2, which is why I figure the option you suggest I turn off is not available on my version??

The only "layer rendering options" I can find are transparency & blending under the style menu.

I also assume that it is off anyway in 2.2, if it is not in the menu?


Thanks

  Brent



________________________________
 From: Nyall Dawson <nyall.dawson at gmail.com>
To: Brent Wood <pcreso at pcreso.com> 
Cc: qgis-user <qgis-user at lists.osgeo.org> 
Sent: Friday, August 8, 2014 1:57 PM
Subject: Re: [Qgis-user] QGIS reprojection broken?
 


Hi Brent,
Try switching off simplification in the "layer properties" - "rendering" tab. Does that help?
Nyall



On 08/08/2014 11:42 am, "Brent Wood" <pcreso at pcreso.com> wrote:
>
> Hi,
>
> Apologies for an attachment to a list email, but I kept it small...
>
> The attached  image shows some Antarctic data (grounding line & ice shelf extent) with a polygon overlayed. 
> I created the polygon by editing a text (csv) file with lat/longs:
> x,y
> 150,-60
> 150,-85
> 255,-85
> 255,-60
>
> I opened it in QGIS (CRS=EPSG:4326) & created a new polygon shapefile layer (snapping to the points) to create a box defined by the same points.
>
> Then I opened the Antacrctic layers (WFS from NSIDC http://nsidc.org/cgi-bin/atlas_south in EPSG:3031 - Antarctic Polar Stereographic)
>  
> I set the QGIS project CRS to a user defined one, same as EPSG:3031, but with +lon_0=180 instead of 0 which gives a 180 up map instead of 0 up.
>
> The map is displayed as in the attached image - a strange box is drawn to the north of the box polygon, the eastern points & vertices do not appear - and if the layer is editable, they cannot be clicked on as nodes. 
>
> If I swap the CRS to EPSG:3031, the inverted map renders the box better (no extra box outside it) but the points are still rendered in a different location to the polygon vertices - but they share the same coordinates.
>
> I can usually work around 180 issues in QGIS by using longitudes in the 0-360 space, but it seems to me that there are some issues with QGIS working in a polar projection across 180.
>
> Does anyone know if there is a way to solve this, or is this an inherent problem for now? In the short term I need to decide whether or not I can progress with QGIS in the cross 180 polar space, or will need to find another tool.
>
> In the longer term, if this is an issue, I'd like to work with a developer to resolve it - and may be able to fund (some of?) the work required.
>
>
> Thanks,
>
>    Brent Wood
>
>
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