[postgis-devel] Found possible platform-specific bug in PostGIS 1.4.0 ?

[Paragon Corporation]

This sounds to me like a difference in GEOS versions.  the
postgis_full_version() will confirm that.

Later GEOS versions can handle unioning a bit better.

Thanks,
Regina 

-----Original Message-----
From: postgis-devel-bounces at postgis.refractions.net
[mailto:postgis-devel-bounces at postgis.refractions.net] On Behalf Of Mark
Cave-Ayland
Sent: Friday, September 11, 2009 9:50 AM
To: PostGIS Development Discussion
Subject: Re: [postgis-devel] Found possible platform-specific bug in PostGIS
1.4.0 ?

Nathan Widmyer wrote:

> Attached are two psql sessions, one on a WinXP Pro SP3 machine, 
> another to Ubuntu Hardy 8.04.  (one pair of files have unix line 
> endings, another has DOS line endings, for your convenience).
> 
> There are 18 polygons in the data set and I want to make a union out 
> of them.  The union works in Linux but fails with an exception in Windows.
> 
> I received an error on the Windows box (TopologyException: found 
> non-noded intersection ...), then brought the data over to the linux 
> box for analysis, and curiously the operation worked.
> 
> If you visualize it, I think the last polygon (#18) shares a common 
> line segment in space with another (possibly #15), but breaks where 
> #18 has a vertex on the line of #15.
> However there are at least 2 polygons that cover the same point in 
> space so the point shouldn't even be a problem because it's not on the 
> outside of the resulting shape.
> 
> I'm sure my analysis is lacking, but wanted to communicate all I found
out.
> Using an alternate strategy of linework does get the union shape though.
> 
> 
> Nathan

Hi Nathan,

Thanks for the analysis and test case. One of the key bits of information
you forgot to include though was the version of PostGIS and PostgreSQL being
used on each box. Can you post the output of the following on both boxes:

SELECT version();
SELECT postgis_full_version();


ATB,

Mark.

--
Mark Cave-Ayland - Senior Technical Architect PostgreSQL - PostGIS Sirius
Corporation plc - control through freedom http://www.siriusit.co.uk
t: +44 870 608 0063

Sirius Labs: http://www.siriusit.co.uk/labs
_______________________________________________
postgis-devel mailing list
postgis-devel at postgis.refractions.net
http://postgis.refractions.net/mailman/listinfo/postgis-devel