[postgis-users] intersection and geometrycollection

[Adam Quiney]

Hi Lia,

Have you tried simply performing the query in the postgres console?  
Does the geometry you get back look valid?  One thing you might want to 
try, just to ensure that everything is working as it should, is creating 
a temporary table holding your new geometry, and then try extracting 
that.  I know that I've run into a few problems with some of the postGIS 
functions like intersection/etc. when trying to pipe them through to 
another application (in my case, JUMP was causing a few problems when I 
tried to display the result of an intersection function).

Something like:

CREATE TABLE temporary_geom_holder AS
SELECT intersection(a.geometry, b.geometry)
FROM blah blah blah...

will create the temporary table for you.

--Adam

Emilia Venturato wrote:

>Sorry for message's object, the problem is with polygon not with 
>geometrycollection.
>Lia
>
>
>Hi,
>I need to extract the intersection between two geometry fields (polygon, 
>polygon).
>I used Intersection(geometry, geometry).
>The results are polygons which I would like to see in QuantumGIS.
>But qgis crash and error is: sql=Segmentation fault.
>I tried also to export as shapefile (pgsql2shp) but just .dbf was created.
>Geometries are valid, simple and the geometry (looked as text) seems right.
>Have you any idea?
>Could you help me?
>Thanks
>Lia
>
>
>  
>

-- 
Adam Quiney
Analyst
Refractions Research Inc.
(250) 383-3022