[Talk-ca] Multipolygon problems

Andrew andrew.allison at teksavvy.com
Fri Jun 30 16:07:20 UTC 2017


User canvec_imports here :-) 

     What would you like me to say? Someone took the approach of
introducing my head to a  2x4 a few years back. Pretty much stopped me
dead in my tracks. 

	1: - I saw the original 
On Fri, 2017-06-30 at 10:40 -0400, Stewart Russell wrote:
> Hi Jochen,
> > I was waiting for user canvec_imports to say something, but there's
been no activity from the account for more than two years. 
> 
> > > > The import was started a long time ago, before there were import
guidelines and very likely before the licence change too. It was done
with the best available data at the time, and done with good intent.
It was a major coup to get government data at the time. 
> 
> > > > > > Since we have the most of these offending polygons in Canada, and
since we're the second largest country in the world, a more bombastic
version of me might be tempted to say, "No, *you're* doing it wrong
...". But that's not particularly Canadian, and even less
constructive. We simply don't have the community available to fix
this. 
> 
> > > > > One thing that we must do is ensure that the sources of Canvec import
data are either fixed or removed from the web. The infrastructure and
documentation for continuing this import and thus propagating these
alleged errors is still out there. Unless it is removed, we could
potentially have a mapper restart the import again.
> 
>  Stewart
> 
> 
> > On Jun 30, 2017 3:54 AM, "Jochen Topf" <jochen at remote.org> 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 <jochen at remote.org>
> 
> > To: talk-ca at 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.htm
l
> 
> > 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  jochen at remote.org  https://www.jochentopf.com/  +49-
351-31778688
> 
> >
> 
> > _______________________________________________
> 
> > Talk-ca mailing list
> 
> > Talk-ca at openstreetmap.org
> 
> > https://lists.openstreetmap.org/listinfo/talk-ca
> 
> 
> 
> --
> 
> > > Jochen Topf  jochen at remote.org  https://www.jochentopf.com/  +49-351-
31778688
> 
> 
> 
> _______________________________________________
> 
> Talk-ca mailing list
> 
> Talk-ca at openstreetmap.org
> 
> https://lists.openstreetmap.org/listinfo/talk-ca
> 
> 
> 
> 
> 
> _______________________________________________
> Talk-ca mailing list
> Talk-ca at openstreetmap.org
> https://lists.openstreetmap.org/listinfo/talk-ca
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/talk-ca/attachments/20170630/de02d2e0/attachment-0001.html>


More information about the Talk-ca mailing list