add location to buildings with negative layer from -1 to -5

[matkoniecz]

General

Affected tag(s) to be modified/added: location
Question asked: Is this building is existing and located underground?

Checklist

Checklist for quest suggestions (see guidelines):

• 🚧 To be added tag is established and has a useful purpose (it is used in StreetComplete itself, allows to clearly mark something as underground - some mappers use solely negative layer/level and expect that it is enough to describe something as located underground)
• 🤔 Any answer the user can give must have an equivalent tagging (Quest should not reappear to other users when solved by one) location=underground/surface/overground/overhead should cover all cases, except complete mistaggings
• 🐿️ Easily answerable by everyone from the outside but a survey is necessary: distinguishing location=surface/overground/overhead requires survey, checking whatever structure exists requires survey
• 💤 Not an overwhelming percentage of elements have the same answer (No spam)
• 🕓 Applies to a reasonable number of elements (Worth the effort)

Ideas for implementation

Element selection: http://overpass-turbo.eu/s/wv2

Metadata needed: no

Proposed GUI:
Related GUI:
Inspired by #907

[goldfndr]

You could simplify the query to way["building"]["layer"~"-.*"]["location"!~".*"]({{bbox}}); in case someone uses a number beyond -5. Although it's improper to exceed -5, such instances can usually be solved by an armchair mapper. openstreetmap-carto accepts integers -99 to 99.

[westnordost]

Well, in StreetComplete, one can use a simplified tag query syntax anyway:
ways, relations with building and layer ~ -.* and !location

[rugk]

Hmm, don't understand this quest. So this is basically correcting a tagging mistake (only tagging layer=).
And when the building is underground, should not it usually be tagged with level?

Here something is tagged with building:levels:underground=1. Is not that enough, so is this location tag really needed?

[ENT8R]

I think it is needed, because without that location=underground tag, there will be underground train stations displayed as normal overground buildings on the map of SC...

[matkoniecz]

So this is basically correcting a tagging mistake

Yes.

Here something is tagged with building:levels:underground=1. Is not that enough, so is this location tag really needed?

At least for me at this moment it is not entirely clear. If that object is entirely underground, I would add also location=underground.

building:levels:underground=1

building:levels:underground=1 may be given to any object that has 1 level underground, not only ones entirely underground.

I think it is needed, because without that location=underground tag, there will be underground train stations displayed as normal overground buildings on the map of SC...

I would add it because it is useful tag explaining situation, not just because one particular data consumer relies on it.