[postgis-devel] isvalid() error

Mark Cave-Ayland m.cave-ayland at webbased.co.uk
Fri Jan 14 00:55:06 PST 2005

> -----Original Message-----
> From: postgis-devel-bounces at postgis.refractions.net 
> [mailto:postgis-devel-bounces at postgis.refractions.net] On 
> Behalf Of strk at refractions.net
> Sent: 14 January 2005 07:23
> To: PostGIS Development Discussion
> Subject: Re: [postgis-devel] isvalid() error
> PostGIS always allowed polygon rings with 3 points.
> In this case it disagrees with GEOS about this.
> Also, PostGIS does not allow 0 points.
> Should we enforce GEOS constraints or just have isvalid
> return FALSE in these cases ?
> --strk;

Hi strk,

Well I can see mention of validity in the OGC spec (see page 20), but I
can't find anything that says invalid geometries should not be accepted? I
also know that we have some polygons here consisting of a single ring with 3
points - does this mean that they cannot be used with any of the GEOS

Kind regards,


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