[Talk-ca] CanVec Reverts

[Sam Dyck]

Micheal

Thanks for contacting us. I must object strongly to your use of the Worst
of OSM example and generally assumption that the data is broken if it
doesn't line up. I checked multiple commercial imagery providers before I
found a digitalglobe image that covered the area during the summer. There
is a large patch of sand between the vegetation-filled area and the coast.
As for the boundary, that comes from another official source, I think it is
supposed to be spaced off of the coastline, though I don't remember exactly
how they calculated it, we would likely need a constitutional change to
make it line up with the coast. Just because things don't match up does not
mean that the data is wrong. Nature doesn't always translate into nice,
clean maps.

Sam

-----Original Message-----
From: Michael Reichert [mailto:nakaner at gmx.net]
Sent: Thursday, 1 September, 2016 01:39
To: talk-ca at openstreetmap.org
Subject: [Talk-ca] CanVec Reverts

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Hash: SHA256

Hi,

unfortunately posting via Gmane does not seem to work (the website is down
but NNTP still works), that's why I have to start a new thread. :-(

Am Tue, 30 Aug 2016 21:41:21 -0500 schrieb Sam Dyck:
> After reading through the changeset discussion, I discovered that one
> of my imports in Northern Manitoba made Worst of OSM.
> (http://worstofosm.tumblr.com/post/22180046353/dear-
> openstreetmap-isnt-it-strange-how-the). As someone who spends a some
> time amount of time in some of relatively unpopulated areas of Canada
> and makes an effort to check the quality of Canvec data (which is
> usually pretty good), I do agree that it is impossible to do
> everything to the same level of quality that we would provide in
> Toronto or Timmins or even small prairie towns.

First of all, it is ok that an import takes a few years and therefore
creates ugly green rectancles on the map. If an import is "unavoidable"
:-), a manual import is the best thing that can be happen. But if someone
uploads a changeset without a manual review beforehand, he counteracts the
aim of a manual import: addind good data to OpenStreetMap. That's what I am
mainly fighting against. If a users uploads much more than 100 objects per
minute [1], you can be sure that he has not done any manual review. A
manual review by myself confirmed this these. I am fighting against such
changesets/users.

A good imports must be reviewed *before* it is being uploaded. The review
contains:
- - Run JOSM validator, fix all warnings and errors. This includes all
warnings regarding validity of areas. (you can argue if all warnings about
"deprecated" tagging have to be fixed)
- - Compare the data with available imagery. Is the forest really a forest
or is another tag more appropiate? Right-click on a Bing tile at JOSM and
have a look how old/recent the imagery is.
- - Check if CanVec data fits to itself.
http://worstofosm.tumblr.com/post/22180046353/dear-openstreetmap-isnt-
it-strange-how-the
<http://worstofosm.tumblr.com/post/22180046353/dear-openstreetmap-isnt-it-strange-how-the>
- - Check if there has been any other data before. If yes, adapt the either
the CanVec data or the old data.
https://wiki.openstreetmap.org/wiki/File:Import-Fails-Powerlines-Not-Ins
ide-Cutting.png
<https://wiki.openstreetmap.org/wiki/File:Import-Fails-Powerlines-Not-Inside-Cutting.png>
https://www.openstreetmap.org/way/439631732
- - Ways should not overlap with other ways if it is not necessary. The
outer ring of a lake should also be inner member of the forest
multipolygon. Maybe the program which created the OSM files should be
imprved?
- - Keep the history.
https://wiki.openstreetmap.org/wiki/Good_practice#Keep_the_history

If a tile has been imported without being checked manually and no
post-upload fixes have been done (i.e. upload without any checks), I will
not shrink from reverting it. If a tile has been uploaded to OSM without a
review and if it has not been fixed within a month, it is worthless and can
easily be reimported at a later time if someone has the time to check and
fix it.

For the future, I will abstain from reverting changesets which have been
imported before September 1, 2016 and whose users are currently doing the
fixes that should already have been done. But if I come across an imported
tile of low quality which has not been touched for a few weeks and is full
of errors, it is just a question of time until it is reverte d.

Best regards

Michael

[1] I had a look on a few of my changesets which added a large number of
buildings to OSM. The fastest changeset contained about 60 objects per
minute and was full of missing buildings as I later detected while
collecting the housenumbers and usage of the buildings.
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