Hi Jochen,
Maybe I'm not understanding it, but in the OSM inspector [1] I just see
one case of old style multipolygon, in Manitoba. Last week, when you
posted your original message, I just saw one case in New Brunswick.
IIRC, it was a park, not even from the Canvec import.
In the OSM inspector other errors can be seen, but the most prevalent
one is "Touching rings". Maybe indeed a case of suboptimal mapping, but
nothing which seems urgent to me.
Here is an example of a forest multipolygon, imported by me
(canvec_fsteggink). It is still version 1, but it has tags on the
relation, not on the rings (except for the quarries): [2]
This is from Canvec v7.0. IIRC, we started at v6.0, and the last version
I know of is v10.0. Maybe v6.0 had wrong tagging, but I'm not seeing any
such cases in the OSM inspector.
So, I'd like to ask you to give a couple of examples where data imported
from Canvec is clearly wrong with regard to old style multipolygon
tagging. When we have clear examples, then it might be easier to come up
with a plan how to fix it. But so far, I see absolutely no reason why
Canada stands out in a negative way. Yes, we all acknowledge that Canvec
data is suboptimal, but as others already have pointed out, mapping
everything by hand in especially remote areas is nearly impossible.
Regards,
Frank
[1] http://tools.geofabrik.de/osmi/?view=areas
[2] https://www.openstreetmap.org/relation/1481163/history
On 30-06-2017 09:52, Jochen Topf wrote:
Hi!
A week ago I wrote this email and nobody answered it yet. Does that
mean that nobody feels responsible for the import that created this data
and nobody here cares for this data?
I see three ways forward:
* We do nothing. The broken data stays in OSM. Not a good solution,
because every user of the data has to work around this or handle the
complaints.
* The Canadian community steps up and fixes the data, automatically or
manually.
* We ask the Data Working Group to remove the broken import.
Jochen
On Thu, Jun 22, 2017 at 11:38:15AM +0200, Jochen Topf wrote:
Date: Thu, 22 Jun 2017 11:38:15 +0200
From: Jochen Topf <joc...@remote.org>
To: talk-ca@openstreetmap.org
Subject: [Talk-ca] Multipolygon problems
Hi!
In the last days the OpenStreetMap Carto Style 4.0 is being deployed on
the OSMF tile servers. This new version of the style doesn't take
old-style multipolygons (where the tags are on the outer ways instead of
on the relation) into account any more. In a huge effort in the last
months we have converted all old-style multipolygons to the modern
tagging, so this is a good step!
Unfortunately, as a side-effect of this change, many multipolygon
relations now appear wrong on the map. This is the case for multipolygon
relations that have the same tags on the relation as well as on (some of
the) outer or inner ways. This is *wrong* tagging, and needs to be
fixed. (Note that this always was wrong tagging, even before we
deprecated old-style multipolygons, but the way the software worked with
old-style multipolygons, this problem was not visible on the map. But
now it is.)
Here is an example: http://www.openstreetmap.org/relation/1330741 . As
you can see (unless somebody fixes this :-) the clearing in the forest
that should just have grass, also has tree symbols on it. In many other
cases it is not this obvious, there are just islands in a river missing
or so.
There are about 50,000 cases like this worldwide, forests, waterways,
all sorts of areas. But the worst problem is in Canada. There are about
15,000 affected relations, most from the CanVec imports.
First, we have to make sure that there are no further imports of broken
data. I hope the people who have done those imports (and might still
continue) are here on this mailing list. If not please make them aware
of this issue and/or put me in touch with them. Second, somebody needs
to clean up the broken data, either automatically or manually. 99% of
the data has not been changed since the import, so it might be feasible
to do an automatic cleanup, but somebody has to do this. Otherwise we'll
have to do a manual cleanup, through tools such as Maproulette and the
OSM Inspector. I am currently in the process of creating Maproulette
challenges for other areas of the planet, but will not do this for
Canada at this time. Lets discuss this here first.
I can provide OSM data extracts, statistics, etc. if somebody wants to
look at the data.
All of this is part of a larger effort to fix areas in OSM. See
http://area.jochentopf.com/ for more information. There is also a thread
on the talk mailinglist at
https://lists.openstreetmap.org/pipermail/talk/2017-June/078203.html
and this issue
https://github.com/osmlab/fixing-polygons-in-osm/issues/36 .
News of the effort are posted regularly to
https://github.com/osmlab/fixing-polygons-in-osm/issues/15 .
Jochen
--
Jochen Topf joc...@remote.org https://www.jochentopf.com/ +49-351-31778688
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