[postgis-devel] Boundary of closed linestrings, part 2

[Sandro Santilli]

On Jan 14, 2011; 09:03pm, strk wrote:
> On Thu, Jan 13, 2011 at 02:37:18PM +0100, strk wrote:
> 
> > While implementing the topology population functions 
> > I've stomped of this odd situation: 
> > 
> >  A closed line has no boundary 
...
> > 
> > This bug is about one problematic consequence of that: 
> > http://trac.osgeo.org/postgis/ticket/770
>
> As it turns out, a closed line has no boundary _by_definition_ 
> according to the OGC Abstract Specification: 
> 
>  Boolean Closed() -- returns TRUE if this geometry has no boundaries 

I've realized that GEOS (starting at 3.2.0) supports specifying
a rule for this [1]. It might be worth exposing that to C-API
and finally into PostGIS, to improve topology costruction performance.

I've filed an enhancement ticket for this [2].

[1] http://tsusiatsoftware.net/jts/javadoc/com/vividsolutions/jts/algorithm/BoundaryNodeRule.html
[2] http://trac.osgeo.org/postgis/ticket/844

--strk; 

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