[postgis-devel] isvalid() error

[Mark Cave-Ayland]

> -----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
functions?


Kind regards,

Mark. 

------------------------
WebBased Ltd
South West Technology Centre
Tamar Science Park
Plymouth
PL6 8BT 

T: +44 (0)1752 791021
F: +44 (0)1752 791023
W: http://www.webbased.co.uk