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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