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

Tom van Tilburg tom.van.tilburg at gmail.com
Sun Oct 15 03:22:54 PDT 2017

I only just found this out and was wondering if it is intentional. When
running ST_SetEffectiveArea it turns out that the triangle-area for points
related to start and endpoint of a polygon are set to dbl_max (example
below). While this is logical for linestrings (it would break your
network), I think it could be implemented better for polygons by
reconnecting the polygon when start/endpoint are throw out because of a
small effective area. I have some polygons with spikes originating from the
startpoint and it is unexpected behaviour to see some spikes not being
removed this way.
Is there a good reason to keep the start/endpoint of polygon intact? And if
so, would it make sense to make it optional?


P.S. I have the idea that this point has been addressed on another list
(maybe D3) but wasn't able to find it.


0 0,
10 0,
20 0,
20 10,
10 10,
10 0,
0 0

"POINT M (0 0 3.40282346638529e+38)"
"POINT M (20 0 3.40282346638529e+38)"
"POINT M (20 10 3.40282346638529e+38)"
"POINT M (10 10 50)"
"POINT M (10 0 50)"
"POINT M (0 0 3.40282346638529e+38)"
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