[postgis-devel] ST_SimplifyVW not touching Start and endpoint of polygon

Sandro Santilli strk at kbt.io
Sun Oct 15 23:12:37 PDT 2017

On Sun, Oct 15, 2017 at 08:07:46PM +0200, Nicklas Avén wrote:

> More complicated, both because it would need different handling of
> linestrings and polygons.

Closed linestrings could be threated the same.
In GEOS, for example, a closed linestring has NO boundary
(ST_Boundary returns the empty set). With this semantic
it doesn't matter where start/end points are, in a closed
line, so can be arbitrary.

But on the other hand I do see reasons for you wanting to
maintain the start/end points (in topology building, for
example, where the start/end point may be a node in a bigger
topology, so please if you allow for changing that make it
an option exposed at SQL level.


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