[postgis-users] What defines a invalid geometry?

[strk at refractions.net]

On Fri, May 13, 2005 at 04:06:24PM +1000, Rhys Ickeringill wrote:
> Hi again list,
> 
> Apologies for the spammin,. just a quick question this time. The processing
> of the query in my previous thread ("Spatial Join Optimisation ") failed
> with a GEOS exception. Running...
> 
> SELECT uid FROM polygons WHERE NOT isvalid( wkb_geometry )
> 
> ... results in 275 invalid geometries out of 100,000 or so.
> 
> During this query there were lots of NOTICE: statementes regarding "Self
> Intersection" and "Ring Self Intersection". Does each of these notices
> correspond to a row returned by my select statement?

Each notice is an invalid geometry, so yes, since all your rows
are NOT isvalid(). --strk;

> 
> Thanks,
> 
> Rhys
> 
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