Re: St_boundary and illegal argument exception

I'm not sure exactly what you are trying to do, but yes, ST_Boundary does extract linework (aka. the boundary) from a polygon.

SELECT ST_AsText(ST_Boundary('POLYGON((0 0, 1 1, 1 0, 0 0))'::geometry));
        st_astext         -----------------------------
LINESTRING(0 0,1 1,1 0,0 0)
(1 row)

Can you isolate the geometry that is causing you grief?
-- Kevin


George Silva wrote:

Hello everyone.

I'm trying to build a function that will transforma one polygon into many lines. I have a lot table, and i would like to insert each line from each lot in a table, containing the id of the lot.

I've tried: SELECT gid, St_boundary(the_geom) INTO lines from lots and postgis gave me an error:

*NOTICE:  IllegalArgumentException: Number of points must be 0 or >3
ERROR:  POSTGIS2GEOS conversion failed

********** Erro **********

ERROR: POSTGIS2GEOS conversion failed
SQL state: XX000*

I'm wondering if that is the right approach? I'm not even sure if boundary is what i am looking for. Can anyone help me? Why postgis gave me this error?

Thanks in advanced.

George


--
George R. C. Silva
Sigma Consultoria

Desenvolvimento em GIS

www.consultoriasigma.com.br <http://www.consultoriasigma.com.br>
www.sigmaconsultoria.blogspot.com <http://www.sigmaconsultoria.blogspot.com>
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