[postgis-users] simplify weirdnesses

[Paul Ramsey]

Markus Schaber wrote:

> Is it desired that a PostGIS operation on valid geometries can make them
> non-valid?
> 
> And it seems that some (well, 65 thousand) Geometries even get
> deleted by simplify. 

It is not desired, but doing otherwise is exceptionally hard. Running 
D-P on polygons in particular is almost certain to cause invalid 
geometries to arise (think about the process of thinning vertices out of 
a polygon -- unless the polygons are completely convex eventually you 
will cause self-intersections). General simplification routines for 
polygons are rocket science.


-- 
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      | Paul Ramsey
      | Refractions Research
      | Email: pramsey at refractions.net
      | Phone: (250) 885-0632
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