[postgis-users] Geomunion problems

[strk at refractions.net]

On Wed, Jan 18, 2006 at 11:58:11PM +1300, Jeremy Palmer wrote:
> Thanks for the test and verification of the error Arnaud and Strk :)
> 
> I have managed to compile temp dataset that now throws "TopologyException:
> no outgoing dirEdge found" GEOS union error.
> 
> I have attached the dataset and the debug log file from the output of the
> geomunion aggregate function. A simple call of "SELECT geomunion(shape) FROM
> statist_areas" should be enough to get the GEOS exception. If someone could
> confirm the same error message on a newer version of PostGIS i.e. 1.1.1cvs
> that would be great :)

That's not a PostGIS related bug, but a GEOS/JTS one.

> Strk what information do I need to log the JTS bug. Is it ok to just post
> the postgis and geos information with the datasets? Also where do I log the
> bug? jts-devel or the JTS sourceforge project page, or somewhere else?

This is not easy, in general, as I verified the bug to only
happen with high precision (a robustness problem most likely).
This means that any attempt at providing an XML test would
result in a successful test being precision reduced by 
the WKT (text) representation.

I'm working in addin HEXWKB support in GEOS XMLTester
so we can check this better in future, I don't know 
about JTS though.

Best thing to do is providing JTS guys with the HEXWKB
format found in the ZIP file you attached before.

> Also if the fix gets done in JTS will the fix also be ported to GEOS anytime
> soon?

That depends on funds availability, currently low.

--strk;