[postgis-users] Overlapping of polygons with SimplifyPreserveTopology

[Paolo Cavallini]

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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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