[Talk-ca] Multipolygon problems

Frank Steggink steggink at steggink.org
Fri Jun 30 22:42:29 UTC 2017

Cette requête dans JOSM peut aider à cherches des chemins avec 
natural=wood et role outer dans une relation: type:way natural=wood 
S.v.p. utiliser avec prudence ;)

This query in JOSM can help finding ways with natural=wood and role 
outer in a relation: type:way natural=wood role:outer
Please use with caution ;)


On 30-06-2017 23:25, Pierre Béland wrote:
> translation follows ...
> James
> la requête overpass ci-dessous extrait pour un bbox les chemins avec 
> role externe dans une relation et avec la même clé natural=wood que 
> sur la relation. De là, il est facile d'effacer la clé en doublon.
> http://overpass-turbo.eu/s/q5K
> Jochen, pour cette première extraction à l'aide de la requête 
> overpass, je constate que la clé en doublon a été ajoutée à plusieurs 
> reprises par un contributeur européen. Merci à lui de nous aider. Puis 
> oui, il faut trouver des façons de progresser comme communauté, cela 
> dans le respect de tous.
> Vous n'êtes pas le premier à venir dire que la carte est mal foutue au 
> Canada. Cela est très démobilisant. Sur la liste talk-ca, nous 
> discutons aussi en anglais et français. Si vous ne faites pas d'effort 
> pour communiquer avec les francophones, vous diminuez encore davantage 
> vos chances de mobiliser la communauté OSM. Il vaut mieux motiver les 
> contributeurs et tenter de comprendre la réalité de grands espaces 
> plus ou moins désertiques tels le nord du Canada, l'Amazonie et 
> certains territoires d'Afrique et d'Asie (moins importants ??).
> Je me rappelle la réponse humanitaire du Mali en janvier 2013 où 
> j'expliquais aux contributeurs des pays du nord qu'une route 
> principale est toujours une route principale, même si elle est 
> ensablée, en mauvaise état, non pavée. La carte, les classifications 
> et les styles sont souvent pensés pour une réalité européenne. Ce 
> n'est pas partout que l'on voit un réseau dense d'autoroutes. Regardez 
> au zoom=5, la carte blanche au nord du Canada ou dans d'autres régions 
> du monde peu denses. Essayez d'y repérer des villages, des routes (non 
> pas des autoroutes), des mines, des barrages.  Bien sûr, il y en a 
> moins de facilités, commerces, fast-food :)  Il y a au nord des 
> villages à des centaines de kilomètres les uns des autres et sans 
> route. Doit-on les ignorer?
> http://www.openstreetmap.org/#map=5/56.969/-83.979
> cordialement
> -------------------------
> James
> The following overpass query extracts the ways with external role in a 
> relation and  with the same key natural = wood as on the relation. 
> From there it is easy to erase the duplicate key.
> Http://overpass-turbo.eu/s/q5K 
> <https://ssl.microsofttranslator.com/bv.aspx?from=&to=en&a=Http%3A%2F%2Foverpass-turbo.eu%2Fs%2Fq5K>
> Jochen,
> on this first area that I extract data, I find that the duplicate key 
> has been added several times by an European contributor. Thanks to him 
> for helping us. And yes, we have to find ways to make progress as a 
> community, with respect for all.
> You are not the first to come and say that the map is screwed up in 
> Canada. This is very demobilizing. On the talk-CA list, we also 
> discuss in English and French. If you do not make an effort to 
> communicate with the Francophones, you will further reduce your 
> chances of mobilizing the OSM community. It would be good also for the 
> global community to try to understand the reality of large, more or 
> less deserted spaces such as northern Canada, the Amazon and some 
> territories of Africa and Asia. These areas look deserted ( less 
> important ??), but believe me, they are not.
> I remember the Mali OSM humanitarian response in January 2013 where I 
> explained to the contributors from northern countries that a major 
> road is always a major road, even if it is sanded, in poor condition, 
> unpaved. The map, classifications and styles are often thought for a 
> European reality. It is not everywhere that we see a dense network of 
> highways. Look at zoom = 5. We see almost nothing in northern Canada 
> or in other areas of the world that are not very dense. Try to locate 
> villages, roads (there are no motorways), mines, dams. Of course, 
> there are less facilities, commerce, fast foods :) Some nordic 
> villages are hundred of km apart. Should we ignore them?
> http://www.openstreetmap.org/#map=5/56.969/-83.979
> regard
> Pierre
> ------------------------------------------------------------------------
> *De :* James <james2432 at gmail.com>
> *À :* Jochen Topf <jochen at remote.org>
> *Cc :* Talk-CA OpenStreetMap <talk-ca at openstreetmap.org>
> *Envoyé le :* vendredi 30 juin 2017 16h04
> *Objet :* Re: [Talk-ca] Multipolygon problems
> If it's just removing tags, on inner polygons of a multipolygon, that 
> should be manageable in itself... is there a way you are querying for 
> said items without setting up a postgresql database?
> On Jun 30, 2017 3:57 PM, "James" <james2432 at gmail.com 
> <mailto:james2432 at gmail.com>> wrote:
>     To be fair....your example is from Canvec 4.0.....that's
>     reaaaaaaaaaaallly old....was it possible that was a way of tagging
>     back in the days? Or was it created initially as a polygon and was
>     later converted to a relation?
>     Canvec 10.0 doesnt have the issues of double tagging, just overlapping
>     On Jun 30, 2017 3:22 PM, "Jochen Topf" <jochen at remote.org
>     <mailto:jochen at remote.org>> wrote:
>         On Fri, Jun 30, 2017 at 08:16:40PM +0200, Frank Steggink wrote:
>         > 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.
>         The types of problems I am talking about don't show up in the OSM
>         inspector. This is not old-style multipolygons (where tags are
>         on the
>         outer ways and not on the relation), but multipolygons where
>         the tags
>         are on the relation AND on the ways.
>         > 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.
>         Here are all cases in Canada (not only those from the imports):
>         https://tmp.jochentopf.com/954 226a3acab882d28d8500ddef8203d/
>         same-tags-ca.pbf
>         <https://tmp.jochentopf.com/954226a3acab882d28d8500ddef8203d/same-tags-ca.pbf>
>         Here is one example where you can clearly see the problem:
>         http://www.openstreetmap.org/r elation/541821
>         <http://www.openstreetmap.org/relation/541821>
>         > 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.
>         Canada stands out in a negative way, because
>         a) there are so many problems. Nearly a third of the cases
>         worldwide are in
>            Canada and
>         b) most of these problems are probably caused by one little
>         program, the
>            program used to convert/import the CanVec data.
>         Mapping Canada "by hand" might be difficult because it is such
>         a huge
>         country and there aren't that many mappers. But the same
>         arguments goes
>         for why you have to be extra careful importing data. If you break
>         something, there are not enough people to fix it manually.
>         And, yes,
>         errors do happen. And if we find them, we fix them and move
>         on. But
>         errors from imports can be so huge there aren't enough people
>         there to
>         fix them manually. So I think it is the job of those who did
>         the import
>         in the first place, to fix their work. If you add data to OSM
>         you take
>         on a certain responsibility. If you add more data, you have a
>         larger
>         responsibility. But saying: We don't have the manpower, so we
>         are taking
>         a shortcut and then, when it turns out the shortcut wasn't so
>         short
>         after all, whining that you don't have the manpower to fix it.
>         That
>         can't be the excuse.
>         Jochen
>         --
>         Jochen Topf jochen at remote.org <mailto:jochen at remote.org>
>         https://www.jochentopf.com/ +49-351-31778688
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