[Qgis-user] Validate geometries with QGis

Borys Jurgiel borysiasty at aster.pl
Thu Apr 16 06:05:33 EDT 2009


Thursday 16 of April 2009 11:58:00 Carson Farmer napisał(a):
> Hi Felix,
> > Hello,
> >
> > I have a postgis table with large polygons. For some of them postgis' 
isvalid function returns false
> > Is there a way to spot these self-intersection places easily?
> >   
> One roundabout way to do this would be to use the 'polygons to lines' 
> tool in fTools to convert your polygons to lines, then use the 
> 'intersect lines' tool (in fTools) to find intersections between the new 
> line layer (use the line layer as both input and intersect layer).
> 
> I haven't tested this myself, but in theory in should work...

Unfortunately it doesn't find self-intersections... Such tool would be worth of 
its weight in gold anyway :)


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