[postgis-users] Polygonize questions

[James DeMichele]

Hi,
I did not find the explanation of this question very satisfying:
 
> * Is there a way to convert a GeometryCollection returned by
polygonize 
> to a MultiPolygon?  Is there any advantage to doing this?
 
Could you expand on possible ways of converting a GeometryCollection
into a Multipolygon?
 
Thanks.
 
-James DeMichele
 
On Sat, Nov 12, 2005 at 03:04:36PM -0700, Charlie Savage wrote:
> Couple of questions about polygonize.
> 
> * Why does it return a GeometryCollection instead of a MultiPolygon?
 
Because it's really a collection of polygons, not a MultiPolygon.
A MultiPolygon must meet certain constraints in order to be valid
(polygons must not intersect) and Polygonize doesn't try to enforce
this.
 
> * Is there a way to convert a GeometryCollection returned by
polygonize 
> to a MultiPolygon?  Is there any advantage to doing this?
 
Check out the dump() and collect() functions.
 
--strk;
 
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James DeMichele | Software Engineer

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