[postgis-users] Union fails on 2389 linestrings.
jadams at azavea.com
Tue Jul 27 07:16:35 PDT 2010
ST_IsValid returns true for all of them. I'll try reducing the
precision slightly, though I'm later going to do point-in-poly checks
against some other original input data and the reduced precision will
increase the chances of inaccurate results.
On Tue, Jul 27, 2010 at 10:13 AM, Nicolas Ribot <nicolas.ribot at gmail.com> wrote:
>> I have a layer with 2389 linestrings which intersect a lot. I'm
>> trying to create a polygon overlay, so I want to union the linestrings
>> together so I can then call polygonize.
>> However, when I try to union them, it runs for about 25 minutes then
>> fails claiming it found a non-noded intersection between two lines
>> that appear identical and 0-length (though it may be the precision is
>> lost when printing the WKT in the error message).
>> create table noded_lines as
>> select ST_Union(boundary) as noded_boundary from boundary_lines;
>> NOTICE: TopologyException: found non-noded intersection between
>> LINESTRING (-118.296 34.1185, -118.296 34.1185) and LINESTRING
>> (-118.296 34.1185, -118.296 34.1185) at -118.296 34.1185
>> ERROR: GEOS union() threw an error!
>> Anyone know how I could get around this?
> Are all your linestrings valid ?
> Could you reduce coordinate precision with st_snapToGrid ?
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