[Qgis-user] Real Mask functionality in QGIS?

[Paulo van Breugel]

On 09-03-17 11:03, Bernd Vogelgesang wrote:
> Am 09.03.2017, 08:28 Uhr, schrieb Neumann, Andreas <a.neumann at carto.net>:
>
>     Hi Hilpers,
>
>     Is this about label and symbol backgrounds?
>
>     We have a QEP about that (see
>     https://github.com/qgis/QGIS-Enhancement-Proposals/issues/63) and
>     an offer from Oslandia.
>
>     Can you please review this QEP and let us know if it matches your
>     needs?
>
>     If yes - would you be able to contribute financially? It is quite
>     complex to implement this and I have to collect around 18k € to
>     finance it. So I would be interested in financial contributions.
>
>     Thank you for your reply,
>
>     Andreas
>
>
> Hi Andreas,
> as I understood the feature request, he means a "real" mask that is 
> not only masking the display, but all features outside of the mask for 
> any geoprocessing.
> I faintly rember this from ArcGIS which I didn't use for ages, so I 
> have no idea how well this is working how its done technically.
>
> But the idea, that when working with numerous layers of different 
> extent, not to have to crop them them each individually to fit into a 
> window of interest, but just to assign a mask layer/bbox to them, 
> sounds very good to me.

This sounds like the mask (r.mask) in GRASS GIS and region (g.region) 
functionality (limits raster operations to defined bbox, amongst 
others), which both are indeed incredible useful functions. If you want 
to use this for geoprocessing in QGIS, you can try it out using the 
GRASS toolbox. The mask function is also available in the processing 
toolbox (r.mask.rast; never tried out how this works though). Note that 
r.mask and g.region both only work for rasters. A similar functionality 
for vector layers would be great, but perhaps more complicated to 
implement (I guess internally it would still use a mask to cut out the 
desired area / region).

>
> Cheers
> Bernd
>
>
>
>
>     On 2017-03-08 21:08, hilpers wrote:
>
>>     Hello everyone,
>>
>>     I regularly face the issue that I want to set masks for layers of
>>     my choice
>>     based on one layer´s geometry.
>>     I know there is a plugin available which handles labels *but not* the
>>     geometry of layers to be masked.
>>
>>     In my oppinion a mask should make geometries / raster cells
>>     outside the
>>     specified mask disappear. The user should also be able to exclude
>>     layers
>>     from being masked. After searching for more than a year, I want
>>     to ask how
>>     you handle this pretty common scenario. Furthermore, four years
>>     after the
>>     last discussion about masks here on QGIS Nabble I also want to
>>     ask, whether
>>     developers are planning to incorporate this feature in V3.
>>
>>     It would be great to have that masking capability option within
>>     the layer
>>     options or even the projects settings.
>>
>>     Thanks
>>
>>
>>
>>     --
>>     View this message in context:
>>     http://osgeo-org.1560.x6.nabble.com/Real-Mask-functionality-in-QGIS-tp5311464.html
>>     Sent from the QGIS - User mailing list archive at Nabble.com.
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>
>
>
> -- 
> Bernd Vogelgesang
> Siedlerstraße 2
> 91083 Baiersdorf/Igelsdorf
> Tel: 09133-825374
>
>
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