[postgis-users] Overlapping of polygons withSimplifyPreserveTopology

[Hugues François]

Hello,

You should also have a look at some functions made by Nicolas Ribot : http://trac.osgeo.org/postgis/wiki/UsersWikiSimplifyPreserveTopology

Topology approach is also described.

Hugues.



-----Original Message-----
From: postgis-users-bounces at lists.osgeo.org [mailto:postgis-users-bounces at lists.osgeo.org] On Behalf Of Paolo Cavallini
Sent: Tuesday, December 10, 2013 7:00 AM
To: postgis-users at lists.osgeo.org
Subject: Re: [postgis-users] Overlapping of polygons withSimplifyPreserveTopology

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Il 10/12/2013 04:49, Luca Morandini ha scritto:

> we noticed that, despite the use of ST_SimplifyPreserveTopology, 
> non-adjacent polygons may overlap; this happens when there is a long 
> and narrow water body of between them (think of a fiord), but this 
> body is not itself a polygon.
> 
> To solve this issue we came up with the idea of adding an "universe 
> polygon"; that is, a polygon that enclose the entire extent of a 
> table, so that every polygon has a left and right
> polygon: would this do the trick ?

Hi Luca,
you really need to use full topology for this.
ST_SimplifyPreserveTopology simply prevents topological errors, it does not guarantee sharing of nodes etc.
Good luck.

- --
Paolo Cavallini - www.faunalia.eu
QGIS & PostGIS courses: http://www.faunalia.eu/training.html
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