Add rendering for wall=no

[bagage]

wall=no should be used for slight construction like a shed or balcony opened on one side at least or without foundation (wiki). It is mainly used in France due to cadastre import:

In OSM French style, it is rendered with lower opacity starting at zoom 18:

[mboeringa]

wall=no + building=yes to denote a one-sided open shed?

Honestly, I really think this kind of stuff simply classifies as building=shed, and should have been tagged and imported as such by the french community (there are some wacko import taggings in the Netherlands where I live too by the way... ).

The fact that the shed is open on one side, could have been tagged differently and more logical and explicit than this. Maybe open_sided=yes as supplement to the documented building=shed tag that is used world wide instead of just in France?

[nebulon42]

I also think wall=no is rather ill-defined.

[mboeringa]

Even more reason to tag with building=shed is that most of these are probably firewood sheds:

https://www.google.nl/search?q=firewood&ie=utf-8&oe=utf-8&client=firefox-b&gws_rd=cr&ei=b0kHWfuJC4iOgAa75JqQBg#q=firewood+shed

which seem to be called like that in English, considering the above Google search...

Maybe another tagging could be:
building=shed + content=firewood

[bagage]

At least in France, wall=no + building=yes can either refer to one of these:

Part of a building (on the right side here):

Roof only structure:

I don't know the history about this choice, but if you think it's misused or could be done better, I'll ask upstream :).

edit: @mboeringa most of these are not building=shed actually, but much more the first image I shown (subpart of a building).

[mboeringa]

I don't know the history about this coice, but if you think it's misused or could be done better, I'll ask upstream :).

Yes, I think that is wise to do... ;-)

The first picture seems to me nothing but a luxury version of building=shed, while the second is clearly building=roof.

If no distinction can be made based on the imported stuff, I guess building=shed is the most logical choice to re-tag them, as building=roof is more often used and associated with bigger structures like roofs on railway or petrol stations, and mostly not used for storage, like a shed and the second picture shown at the bottom.

[dieterdreist]

2017-05-01 16:50 GMT+02:00 mboeringa <notifications@github.com>:

The first picture seems to me nothing but a luxury version of *building=shed*, while the second is clearly *building=roof*. If no distinction can be made, I guess *building=shed* is the most logical choice to re-tag them, as *building=roof* is more often used and associated with bigger structures like roofs on railway or petrol stations, and not used for storage, like a shed.

+1, there is documentation for wall=* as a subtag for barrier=wall, where wall is used to provide details about the wall, even the French version doesn't mention "no" as value (although it is very common due to your import). https://wiki.openstreetmap.org/wiki/Key:wall I would agree with building=* and wall=no being a synonym for a building=roof with no walls, but in the case of at least one wall it seems wrong (no is no, not?)

[bagage]

Just to be clear and ensure that we all are on the same page.
France buildings are semi auto-imported from the French land register / cadastre.
It contains almost all French buildings position and one single extra information: if the building is of type "heavy" or "light".
"light" may basically means one of the following:

So I don't think any building=* value will match all these cases simultaneously.
On the other hand, dropping this information totally would be regrettable. This is the reason why another tag (wall=no) is used.
In the mean time, this information is actually not rendered while it could be useful. This is somewhat relative to symbol 526.2 "Canopy" / 852 Building pass-through used in orienteering, which interestingly has no equivalent in OSM:

[mboeringa]

I really think rendering of this tag is a dead end. I think the French community should reconsider what they want to do with this information:

1. • Revert this part of the building import and start from scratch mapping this when needed with more appropriate tags
2. • Keep it as is and accept unlikely support in a lot of renderings
3. • Start enhancing the data by classifying it using more useful tags by field or imagery observation, e.g.:

• building=shed (+ content=firewood in specific cases?)
• building=roof
• building=greenhouse
• amenity=parking + building=yes
• whatever else seems appropriate and has tag and rendering support.

Personally, I'd go for 3)... The particular wildly varying mixture of buildings and structures you are showing for a "light" building, also strongly points in the need to enhance tagging using more appropriate tags and field observations.

[dieterdreist]

On 6. Jun 2017, at 22:27, mboeringa ***@***.***> wrote: Start enhancing the data by classifying it using more useful tags by field or imagery observation

+1, just because the cadastre didn't provide more building detail doesn't mean France has to remain at that level, you can always improve this first version with more precise tagging from survey

[bagage]

Yes obviously that's what we must target. But in the mean time should we just ignore this information? Why rendering building=yes in that case, since this is the same issue?
We all agree that building=yes wall=no is some generic tagging which must be improved, but I just wanted to have a better map rendering until we reach the "perfect mapping" of descripting every single building with proper building=* type (almost 5% of France buildings are not imported yet, so we are far from having "time" to specify every buildings).
If it doesn't make sense for you… well I cannot argue more actually :).

[HolgerJeromin]

Just to remember: osm-carto does not render any light buildings different #2532 then building=yes.
If we decide to render them (roof? garage? shed?) we could decide to include french light buildings, too.

But this style is (also) a mapper feedback loop not (only) to have a nice looking map. If osm-carto would render french-light building special who would stand up and clean up the import?
For example I never bothered about special building tags for residential buildings but tagged all =yes. No i have an app (streetcomplete) which asks building:level and roof questions for building=house/detached...
=> i tagged a few thousands in my hometown.

[matkoniecz]

I am not convinced that supporting and encouraging this tag is a wise choice. If light/minor/shedlike building are to be rendered differently I think that building=* value should be used.

I plan on closing it per @mboeringa comments.