[postgis-users] GEOS union() error

[Paul Ramsey]

Lee, what are you going to do with this beast once you have created it?
P

On 6-Nov-07, at 10:41 AM, Lee Keel wrote:

> Hello list.
>
> I am trying to get a multipolygon from a union of buffered  
> linestrings.  See attached (bad_drawing.jpg) to see what I am  
> trying to achieve.  I have some linestrings, I want to buffer each  
> line by 400 feet, then combine all of those buffers to create one  
> multipolygon.  My thought was to do something like:
>
> select geomunion(buffer(the_geom, 400)) as the_geom from main
>
> However, when I do this, then I get the following error:
>
> NOTICE:  TopologyException: side location conflict (901411,1.03413e 
> +006,1.03413e+006)
>
> ERROR: GEOS union() threw an error!
>
> SQL state: XX000
>
>
> Now my guess is that the geomunion is throwing the error because  
> the buffers overlap and of course that would be an invalid  
> polygon.  So, could someone purpose a different approach to doing  
> this?  Or tell me what I am doing wrong.
>
>
> <<bad_drawing.jpg>>
>
> Thanks in advance,
>
> Lee
>
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> <bad_drawing.jpg>
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