[Tagging] Requiring area=yes with barrier=wall, barrier=hedge and other usually linear features when mapped as an area`1

Joseph Eisenberg joseph.eisenberg at gmail.com
Sat Apr 13 00:37:34 UTC 2019

Question: Will mappers understand if adding or taking away "area=yes"
from a closed way changes the rendering?

Background: Right now the wiki pages for barrier=wall and
barrier=hedge allow these features to be mapped as an area, but the
closed way is supposed to have the tag "area=yes" added to make it
clear that this is an area, rather than a linear feature that happens
to be in a circle. This is also the case for a number of other
features that are usually mapped as lines but can also be mapped as
areas, eg piste:type=downhill, piste:type=nordic.

Currently the ID editor is supposed to always add the tag "area=yes"
to features that can be mapped as an area or a line when the user
selects the type area while mapping. (I'm not sure if JOSM is as
consistent about recommending this or checking during validation).

Example: I'm considering using the tag "area=yes" to check if a
barrier should be rendered as an area. Right now "barrier=hedge" is
rendered as an area in the Openstreetmap-carto if it is imported as a
polygon. This happens for all closed ways that are tagged "area=yes",
but it also happens if the closed way is tagged with both
"barrier=hedge" and "landuse" or "natural" or "amenity", because these
keys are normally imported as areas.

It's not ideal to map 2 different features using the same way, but it
happens commonly.

So we could fix some rendering mistakes by checking for the presence
of "area=yes", and only render the fill color for hedges if there is
an "area=yes" tag. This could also work for things like

Do you think that mappers will be able to figure out the problem if
the rendering changes when adding or removing area=yes?

Will validators in JOSM and other editors be able to point out a
problem if a closed way is tagged with both "area=yes",
"barrier=hedge" and "landuse=meadow"?

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