[Qgis-user] Union Tool - Ftools/Sextante - How should the real result be

[Bernhard Ströbl]

Hi Vinayan,

just some comments:
IMHO features in layers to union should not overlap within one layer 
(e.g. landuse is either A or B), so your examples are theoretical only. 
Example 1 does not make sense in this respect. Example 2: If we assume 
that the circles in layer 2 do not overlap and the overlapping area is 
only part of the left hand circle (1) the union operation should result 
in what you show (except the overlapping area would be only one polygon 
with A=1 and B=X)

Bernhard

Am 06.05.2013 17:05, schrieb vinayan:
> Hi,
>
> At present the union tool does not give correct results in sextante/ftools.
> After looking at some bug reports, I feel that even in QGIS 1.8, the union
> tool was not producing the correct output either attribute-wise or
> geometry-wise.
>
> My question is how should the real output be? I have two cases here.
>
> 1. Union of a single layer against itself  -
> https://www.dropbox.com/sh/asicnvr71vxeaz2/TKVUpdleIX#f:singleLayerInput.png
> 2. Union between two different layers -
> https://www.dropbox.com/sh/asicnvr71vxeaz2/TKVUpdleIX?lst#f:twoLayerInput.png
>
>
> It looks to me that for case 1, the result could be like below(11 geometries
> in total)
> https://www.dropbox.com/sh/asicnvr71vxeaz2/TKVUpdleIX?lst#f:singleLayerResult1.png
>
> and for case 2, the result could be like below
> https://www.dropbox.com/sh/asicnvr71vxeaz2/TKVUpdleIX?lst#f:twoLayerResult1.png
>
> what do you think? Anybody knows how it looked in 1.8?
>
> Thanks
> Vinayan
>
>
>


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