On 11-02-19 09:27 PM, Jonathan Crowe wrote:
This is rather discouraging and frustrating.
When the Bing imagery was made available, I spent a fair amount of
time cleaning up the maps in Aylmer, Quebec, a western suburb of
Gatineau. Just discovered that my edits have been overwritten by
another user importing CanVec data.
This import has introduced hundreds of errors:
- Proposed and under-construction streets are shown as completed.
- Streets are tagged as unclassified.
- Service roads have been removed altogether.
- Turning circles and traffic signals are missing.
- Certain streets do not line up with high-resolution Bing imagery,
and not in an off-by-a-few-metres way -- for example, the Bing image
has a subtle S-curve, the CanVec data has a rather crude straight line
bisecting the curve.
This means that Aylmer now needs dozens of person-hours to get it back
to where it was -- and at this point I'm discouraged enough to say the
hell with this project and find something better to do with my spare
time.
Much of Ottawa is in a similar state: manual edits superimposed with
CanVec imports that may or may not have been more accurate, and now
there are two or three duplicates on top of one another. It's a mess,
and it's in no way ready for MapQuest.
I thought CanVec imports were frowned upon when there was existing road data?
I'll tell you this: this is not the way to encourage people to
contribute, if all the work we do with imagery is subject to
obliteration by someone else's work with government vector data.
Yours in frustration,
Jonathan Crowe
The Map Room: A Weblog About Maps
http://www.maproomblog.com/
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Hi Jonathan,
I'm sorry to hear that this has happened. Imported data should generally
not replace user-contributed data, unless the quality difference is obvious.
Probably the best way to proceed is that someone who has good experience
with reverse tools to contact you, as well as the offending importer. It
is best to identify the changesets of the imports, and revert them. This
should also restore your contributions, as well as those of other users
in the area. Perhaps the import is done in multiple phases (as if the
import is done from a clean slate), so more changesets might need to be
identified.
In case there is data missing, you and other active users in the area
could decide whether you guys will take it upon yourselves to add it to
the map, or import non-duplicate data.
Unfortunately this mistake has been picked up by osm-talk, ensuing in a
renewed discussion about how "bad" imports are. Imports _themselves_ are
not bad by themselves. The problem lies with the _individuals doing
imports_ who are not following proper conduct (like a careful evaluation
of existing and new data, too lazy to pay attention / clean up, etc.).
I'm saying this as someone who has done both user contributions and
imports. When importing data, and encountering conflicts (duplicate
data) during the cleanup stage, I'm always asking myself if I would
prefer to keep it if I were the user who added it. If unsure, I'll
consult the Bing imagery as a judge. Of course I'm doing this cleanup
according to my own guidelines, but I strive to take an objective stance
as much as possible. This mostly applies to my import work in the
Netherlands (landuse data), where this situation arises much more often
than in Central Québec (where I've recently picked up Canvec, for now
sans roads...).
This process is difficult and very tedious, but I'm glad to say that
since I started doing large scale imports 1 1/2 years ago (first Geobase
NRN), I've received way less complaints than positive comments. And in
nearly all cases we came to some agreement. The only time where this
isn't the case, happens to be in my backyard, but I'll pick that up with
Bing some day... At least I managed to convince that user that the
quality of the Dutch landuse data isn't nearly as bad as he painted. He
also happened to use a cellphone only to record GPS tracks.
Regards,
Frank
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