AW: [postgis-users] Detecting holes in geometries

Thorsten Kraus Thorsten.Kraus at
Fri Aug 24 02:06:16 PDT 2007

Thanks. Unfortunately this function is only defined for polygons, but my geometries are of type multipolygon :( 
A cast like this did not help: SELECT AsText(InteriorRingN(geom::POLYGON,1))  from xxxportugal2dig_s.
Is there any other possibility to get the hole position out of a multipolygon?

-----Ursprüngliche Nachricht-----
Von: postgis-users-bounces at
[mailto:postgis-users-bounces at]Im Auftrag von
Barend Köbben
Gesendet: Freitag, 24. August 2007 10:59
An: PostGIS Users Discussion
Betreff: Re: [postgis-users] Detecting holes in geometries

 SELECT AsText(InteriorRingN(geom),1) AS geometryOfHole from areas

Would get you the geometry of the 1st hole as OGC Well-Known Text...

Barend Köbben
International Institute for Geo-information
Sciences and Earth Observation (ITC)
PO Box 6, 7500AA Enschede (The Netherlands)
ph: +31 (0)53 4874253; fax: +31 (0)53 4874335

On 24-08-2007 10:15, "Thorsten Kraus" <Thorsten.Kraus at> wrote:

> Hello,
> I am able to detect the number of holes in a geometry with the following sql
> statement:
> SELECT SUM(NumInteriorRings(geom)) AS countHoles from areas
> Is there any possibility to get the position where the holes are?
> Regards,
> Thorsten
> _______________________________________________
> postgis-users mailing list
> postgis-users at

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