[Qgis-user] Running v.clean on a QGIS vector layer (Polygon) through Sextante

[Bernd Vogelgesang]

Hi,
don't know if i understand the matter correctly, but what i extracted from  
Stefans initial question is, that there is no v.in.ogr accessible in  
Sextante, and therefore no advanced options for snapping and minimum areas  
to import from e.g. shape files.
Especially for badly digitized polygon layers, this one-time import into  
GRASS with the advanced options cures almost all errors for me in 99% of  
the cases.

v.clean.snap, as it was suggested by Paolo, is no alternative for that,  
cause snap seems not to handly polygons but only lines! ("snap: snap lines  
to vertex in threshold" from grass manual).
So, i never found an easy way for topologically cleaning polygon layers  
through other v.clean functions as easy as with v.in.ogr, but as long as  
it's not accessible in Sextante, i still have to manually import it in  
GRASS (with all the mapset and location hokuspokus, most people do not  
understand)

Maybe i'm completely on the wrong track. In this case: Please direct me ;)

Cheers
Bernd

Am 30.04.2013, 17:02 Uhr, schrieb Paolo Cavallini <cavallini at faunalia.it>:

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> Il 30/04/2013 13:46, SBL ha scritto:
>
>> What I did not understand completely was: Do you mean that the default
>> settings of v.in.ogr are being used (snapping disabled and min_area set  
>> to
>> 0.0001) or is the topology cleaning completely disabled in the  
>> v.in.ogr-part
>> of Sextante?
>
> The first one.
>
>> So maybe importing and exporting to and from GRASS could be used to  
>> perform
>> a quick, simple and beginner-friendly "lightweight-cleaning"?
>
> You can use v.clean for this
>
>> I see this also as a solution for  Bug #2921
>> <http://hub.qgis.org/issues/2921>  , which furthermore offers additional
>> quality checks...
>> Actually, before I learned about the possibility in Sextante I  
>> considered
>> creating a plugin for that...
>
> Never reinvent the wheel; but you're always welcome to come and help  
> improving
> Sextante, e.g. adding unit tests - it's easy, Victor can explain how.
> All the best.
> - --
> Paolo Cavallini - Faunalia
> www.faunalia.eu
> Full contact details at www.faunalia.eu/pc
> Nuovi corsi QGIS e PostGIS: http://www.faunalia.it/calendario
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