[postgis-users] ST_SimplifyPreserveTopology creates invalid geometry

Darafei "Komяpa" Praliaskouski me at komzpa.net
Tue Mar 10 10:48:01 PDT 2020

ST_MakeValid by definition does anything it likes, the only thing that
should happen: output is valid and no vertices are lost. The "no
vertices are lost" forbids to discard the hole.
If MakeValid will change behavior there it will stop being useful for
"inners and outers are marked incorrectly" case and won't be exactly
useful for yours, so I'd not touch it.

On Tue, Mar 10, 2020 at 8:19 PM Paul van der Linden
<paul.doskabouter at gmail.com> wrote:
> > This is a known bug in the Topology-Preserving Simplfier.  For instance see
> > https://github.com/locationtech/jts/issues/428
> >
> > I'll add your example to the ticket.  Hopefully this can be fixed sometime
> > soon.
> Thanks!
> And what about ST_MakeValid converting that hole into an outerring instead of just discarding it?
> Is that something that's worth a discussion?
> Paul
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Darafei Praliaskouski
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