[mapserver-users] msOGRFileNextShape(): OGR error. TopologyException: side location conflict

[Frank Warmerdam]

Friend Vn 2000 wrote:
> I still get this error now ( I use MS4W v2.3.1 - mapserv 5.2.1 ).
> My data source is a .mdb Personal Geodabase file. This is the first time 
> I use this kind for input. I found the map engine doesn't work stably 
> and this error appears frequently. Sometime the error not shown but some 
> features in the map disappear mysterious-ly.
> Thanks!
> 
> --- On *Thu, 3/26/09, Daniel Morissette /<dmorissette at mapgears.com>/* wrote:
> 
> 
>     From: Daniel Morissette <dmorissette at mapgears.com>
>     Subject: Re: [mapserver-users] msOGRFileNextShape(): OGR error.
>     TopologyException: side location conflict
>     To: "MapserverList OSGEO" <mapserver-users at lists.osgeo.org>
>     Date: Thursday, March 26, 2009, 6:36 AM
> 
>     Tamas Szekeres wrote:
>      >
>      > msDrawMap(): Image handling error. Failed to draw layer named
>     'MainStreet'.;msOGRFileNextShape(): OGR error. TopologyException:
>     side location conflict 19.0499 47.5334 1.7e-308
>      >
>      > Does anyone know where this error is coming from? I've seached
>     for these strings in the MapServer and OGR code but didn't find any hit.

Friend,

I believe this error is coming from GEOS and likely occurs when the geometries
from the file are translated into GEOS format in order to do a spatial
comparison test against the map view within OGR.

This likely is due to a linestring or polygon being invalid - perhaps due
to self-intersection.

Actually, I'm surprised that things would dip into the GEOS geometry
comparisons. MapServer is careful to only set rectangular spatial filters
and OGR is supposed to short circuit this case to avoid GEOS.  I'm not really
sure why you end up in GEOS.  Are you doing any other fancy stuff that
might end up in GEOS?

If you could boil this down to something similar I could use to reproduce
the problem, I would be willing to have Chaitanya look into it.  It would
need to be filed as a GDAL ticket.

Best regards,
-- 
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