[postgis-users] St_boundary and illegal argument exception

[George Silva]

I ran a st_isvalid on all features of my table. I had 4 invalid features.
deleted em, everything worked.

But how about transforming that linestring, into lines?

Example, i have a square, and i need to have all four lines that compose it
into separate records.

Is that possible?

George

On Fri, Jun 26, 2009 at 11:41 PM, Kevin Neufeld <kneufeld at refractions.net>wrote:

> 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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-- 
George R. C. Silva
Sigma Consultoria

Desenvolvimento em GIS
www.consultoriasigma.com.br
www.sigmaconsultoria.blogspot.com
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