Hi
Am 07.05.2013 16:21, schrieb Ivan Santiago:
In this bug report:
http://hub.qgis.org/issues/4567
there is a link with the data provided:
http://hub.qgis.org/attachments/5563/shapes_and_fake_polys.zip
Giovanni Manghi updated the report:
...the tool is not wrong, in fact if you see in detail (see attached
screenshot) the two polygons that seems wrong after the union are not identical
in the input layers, there is a very small difference, something like 0.4 mm...
but this makes them two non identical, overlapping polygons...
It would be n i c e if the use can provide a tolerance to the tool. In this
way, this would avoid some of the spurious data that appear when doing overlays.
IMHO this would be dangerous because normally you would not know
beforehand the result of your overlay operation. A better approach is to
do your overlay and then examine the result. The overlay operation must
of course work correctly, which fTools - unfortunately - currently does
not (I used intersect yesterday and the resulting polygons had wrong
attributes). If you want to get rid of sliver polygons after the
overlay, use the eliminate tool in fTools. It is then up to you what
qualifies as sliver, not up to an algorithm.
Bernhard
---------------------------
Iván Santiago
GIS Specialist
Information Technologies
Office of Management and Budget
787.725.9420 x 2378
Calle Cruz 254
PO Box 9023228
San Juan, PR 00902-3228
-----Original Message-----
From: Victor Olaya [mailto:vola...@gmail.com]
Sent: Tuesday, May 07, 2013 10:02 AM
To: Ivan Santiago
Cc: senhor.n...@gmail.com; qgis-user@lists.osgeo.org
Subject: Re: [Qgis-user] Union Tool - Ftools/Sextante - How should the real
result be
Ivan
could you provide some small dataset where you are seeing that?
Information about SEXTANTE version is also welcome (I assume you are using the
latest QGIS master, but just in case...There is no need to reinstall SEXTANTE,
just reinstall the latest QGIS dev, which includes
SEXTANTE)
Thanks!
2013/5/7 Ivan Santiago<isanti...@ogp.pr.gov>:
Hello:
I downloaded (now) and reinstalled Sextante.
Unfortunately the results were the same, holding duplicate polygons
when using Union tool.
It is easy to see the dups applying transparency.
---------------------------
Iván Santiago
GIS Specialist
Information Technologies
Office of Management and Budget
787.725.9420 x 2378
Calle Cruz 254
PO Box 9023228
San Juan, PR 00902-3228
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