[postgis-users] Self-intersecting polygon gives ST_IsSimple=true

[Sandro Santilli]

On Mon, May 08, 2017 at 08:49:24PM +0300, Jukka Rahkonen wrote:
> Jukka Rahkonen kirjoitti 2017-05-08 17:33:
> >Jukka Rahkonen kirjoitti 2017-05-08 15:48:
> 
> >I can still find the same comments about polygon validity in
> >https://github.com/locationtech/jts/blob/master/modules/core/src/main/java/org/locationtech/jts/operation/IsSimpleOp.java
> >beginning from line 205
> >
> > /**
> >   * Computes simplicity for polygonal geometries.
> >   * Polygonal geometries are simple if and only if
> >   * all of their component rings are simple.
> >   *
> >   * @param geom a Polygonal geometry
> >   * @return true if the geometry is simple
> >   */
> >
> 
> 
> I was remembering that JTS list is a bit slow with answers so I compiled JTS
> from master https://github.com/locationtech/jts.
> IsSimple with POLYGON ((320 620, 460 620, 460 500, 320 620, 320 500, 180
> 500, 180 620, 320 620)) gives false so JTS and GEOS have different behavior.
> 
> I am new with PostGIS project, do the developers consider this as a bug and
> do you want me to file an issue? If yes, would it be a GEOS bug
> https://trac.osgeo.org/geos/newticket?

Yes please, it'd be a GEOS bug but it's also useful to file it as a
PostGIS bug (in case there's any shortcircuit there).

--strk;