[Tagging] Multipolygon (several outers) forest with different leaf_types: mapping strategy?

Warin 61sundowner at gmail.com
Thu Mar 14 00:23:05 UTC 2019


On 14/03/19 10:36, Joseph Eisenberg wrote:
> Normally we should map features that are “real” and “current”, and is 
> easiest to do for things that can be observed in person.
>
> This suggests mapping each patch of trees as a separate polygon or 
> closed way, based on having the same leaf_type and leaf_cycle. Usually 
> it’s only necessary to use a multipolygon when there is a hole in a 
> donut-shaped woodland. Each area should be tagged natural=forest or 
> natural=wood in addition to the leaf_type/leaf_cycle tags

+1
>
> So then the problem is, how do you show that all of these patches of 
> trees are part of one “forest”?
>
> How can another mapper verify where the named “forest” ends? Is it a 
> type of boundary=protected_area that is designated by the local 
> government or private landowner? Is there a fence around the whole 
> area? It looks like it is not a single continuous area, so this makes 
> it even harder to verify where the named forest ends.

A site relation could be the best solution?
>
> I don’t know much about the original poster’s example, but it looks 
> like the name is “<Village name> Communal Forest”, and the areas 
> included in the relation are on separate sides of the village and 
> divided by farmland. Also, there are other areas of woodland right 
> next to the edge of this forest.
>
> Perhaps this is mapping land ownership parcels rather than a “real” 
> physical feature?
>
> -Joseph
>
> On Wed, Mar 13, 2019 at 11:14 PM marc marc <marc_marc_irc at hotmail.com 
> <mailto:marc_marc_irc at hotmail.com>> wrote:
>
>     Le 13.03.19 à 14:59, David Marchal a écrit :
>     > the JOSM validator claims that contiguous outer members is an error
>
>     yes it's- the sum of all outer should not have a "internal" way
>     like this one
>     https://www.openstreetmap.org/relation/9393253#map=17/48.42219/5.92713
>     so draw a new way for the outer of this part
>     or split currents ways to include only the outer part in the relation
>     and make another relation for the leaf_type
>
>
>     > openstreetmap.org <http://openstreetmap.org> renders a misplaced
>     name
>
>     It doesn't seem so misplaced
>     https://www.openstreetmap.org/#map=15/48.4222/5.9197
>     but that's not due to the tag
>
>     > no leaf_type
>
>     it's hard to render a forêt with several leaf_type
>     you may put natural=wood landcover=trees to every part of the forêt
>     having a different leaf_type
>     but you 'll have a duplicate forest : a foret at the relatin level
>     and
>     at every part. currently i'm not aware of a good schema to avoid this
>     (you can trick some QA tools by using landuse=forest for the
>     relationship and natural=wook for all parts, but see the wiki for
>     forest, the meaning of these 2 tags is random/variable depending
>     on the
>     mapper, the only meaning you can get is "there are trees", the same
>     meaning for the 2 tag)
>
-1. Best not to try and 'trick' things, gets confusing too quickly.

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