[postgis-users] Well done with GEOS & QGIS!!!

Brent Wood pcreso at pcreso.com
Wed May 9 20:13:50 PDT 2007

Instead of asking for help or features, just for a change I figured I'd pass on
some thanks for something working perfectly (touch wood, fingers crossed....

I just ran difference() & got a GEOS error:
NOTICE:  TopologyException: found non-noded intersection between 173.56
-35.3436, 173.558 -35.3364 and 173.56 -35.3412, 173.557 -35.3388 173.559
ERROR:  GEOS difference() threw an error!

It sort of made sense, & suggested there was a topology error in my polygon.
I ran isvalid() & got a false on the very polygon I was using in difference,
along with the message:
NOTICE:  Self-intersection at or near point 173.559 -35.3407

Wow!!! All I needed to know! 

Opened it up in QGIS, zoomed in & there it was, make it editable, drag some
vertices around to fix the error, save it, re-run the SQL & it worked

Fantastic to see this level of useability, interoperability  & topology support
coming out of these tools.

Kudos to all you developers out there!!!


  Brent Wood 

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