[postgis-users] ST_SimplifyPreserveTopology creates invalid geometry

Martin Davis mtnclimb at gmail.com
Tue Mar 10 11:17:05 PDT 2020

On Tue, Mar 10, 2020 at 10:19 AM Paul van der Linden <
paul.doskabouter at gmail.com> wrote:

> And what about ST_MakeValid converting that hole into an outerring instead
> of just discarding it?
> Is that something that's worth a discussion?

Yes, that's a hard call.  In this case it seems "obvious" that the small
hole should be discarded.  But there are equally well other cases where a
user might feel that rings have been mis-assigned as holes, and should be
turned into shells.

Personally I prefer the former semantics (discard holes not inside shells),
since that seems simpler.  But it's a highly debatable point.  ST_MakeValid
is a pretty blunt hammer.
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