[postgis-users] ST_Union (8.4) and TopologyException
kneufeld at refractions.net
Tue Aug 4 22:23:19 PDT 2009
I've found that such errors in the past are usually related to the
precision of the coordinates. Try putting your geometries through
ST_SnapToGrid(), snapping them to some reasonable grid. Ensure they are
still valid and try ST_Union again.
In any case, TopologyExceptions are getting fewer and farther between as
the JTS and GEOS codebases are continually enhanced and improved upon.
Can you provide a concrete example?
Simon Greener wrote:
> I have been trying out the new ST_Union in 1.4 and have a question.
> I note that, whenever I hit an error like this:
> NOTICE: TopologyException: found non-noded intersection between 5.74214e+006 7.36573e+006, 5.74304e+006 7.36666e+006 and 5.74339e+006 7.36629e+006, 5.74304e+006 7.36666e+006 5.74304e+006 7.36666e+006
> ST_Union fails to produce a result.
> Is there anything I can do to address this TopologyException issue within PostGIS.
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