Hi All,
The current thread with subject line "Re: [Qgis-user] Topology Checker
Plugin" is a perfect example of my favourite Bee that lives in my bonnet.
Firstly a BIG +1 for open source is that you CAN look at the
source-code, and there are a lot of people out there who are willing to
give you an opinion based on their experience.
The big -1 for closed source is that the methodology of any button
marked "Magically fix my data" is a closely guarded secret - so you have
no idea what it is fixing or b*ggering up.
SO, people out there, KNOW your data.
It cannot be fixed (reliably) by someone who does not know what your
data is trying to achieve.
For example: When is an overshoot a cul-du-sac and when is it an overshoot.
If the person writing the fix-up routine knows that your network is a
water network, may it will be flagged as an overshoot. If they know it
is a road network, maybe it is a cul-du-sac? But then, what if one of
the roads is attributed as a freeway?
So, the best way to fix your data is to write the feature-relationships
yourself, and to write (or run) the fixup scripts with the appropriate
parameters when possible, or not run them (the 'canned' ones) at all,
unless they give you a list of where to look, rather than quietly fixing
it the way some programmer thinks it should be fixed.
AAAARGH!
OK, I'm quiet now.
End of rant.
Regards,
Zoltan
:-)
--
===========================================
Zoltan Szecsei PrGISc [PGP0031]
Geograph (Pty) Ltd.
GIS and Photogrammetric Services
P.O. Box 7, Muizenberg 7950, South Africa.
Mobile: +27-83-6004028
Fax: +27-86-6115323 www.geograph.co.za
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