[postgis-users] ST_MakeValid

Stephen V. Mather svm at clevelandmetroparks.com
Tue Apr 17 07:32:24 PDT 2012

That seems like it would make a big performance difference in this case.

Stephen Mather
Geographic Information Systems (GIS) Manager
(216) 635-3243
svm at clevelandmetroparks.com

-----Original Message-----
From: Sandro Santilli [mailto:sandro.santilli at gmail.com] On Behalf Of
'Sandro Santilli'
Sent: Tuesday, April 17, 2012 4:50 AM
To: Stephen V. Mather
Cc: 'PostGIS Users Discussion'
Subject: Re: [postgis-users] ST_MakeValid

On Mon, Apr 16, 2012 at 03:05:21PM -0400, Stephen V. Mather wrote:
> > IIRC there's a difference with a multipolygon composed by two
> > overlapping rectangles.
> Rereading, does ST_MakeValid also test for overlapping polygons? 

It handles those too, yes.
Basically it nodes and polygonizes all boundaries of input polygons
and then maximizes the vertices retained in output by toggling
between interior and exterior at every boundary. When impossible,
the line is retained as a linestring.


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