[Tagging] how to map simple buildings

Martin Koppenhoefer dieterdreist at gmail.com
Thu Mar 2 16:19:35 UTC 2017

Thank you for the extensive answer. Here are some comments:

2017-03-02 15:24 GMT+01:00 "Christian Müller" <cmue81 at gmx.de>:

> I usually go for a mixture of 1.1. and 1.3., i.e.
> - use building:part for the architectural blocks the building is made of,
> with building:min_height / building:min_level where appropiate
> - use type=multipolygon building=*, stuff the usual building tags into
> that,
> this will be rendered by non-aware 3d renderers, i.e. serves backward
> compat
> and will be added in role outline to the following
> - use type=building relation to group together outline and parts,
> see http://wiki.openstreetmap.org/wiki/Relation:building
> (though I've never used ridge or edge roles)

do I understand you correctly, we use 1 way (or multipolygon) for every
building:part plus 1 multipolygon relation with building=* as a fallback
plus 1 type=building relation for every single building? That's a lot of
stuff, but it sounds reasonable in order to map everything in an
unambiguous way.

> As for your point 2. - afair simple buildings allows to define
> roofs only along with building:part, so there is no extra
> mechanism to define roof elements separated from those.

yes, my question was refering to the building:levels tag: where to count
the levels, as part of the roof or of the "main part" of the building

> If you have a roof that deviates a lot from the building
> parts it covers (or you want to define the roof as a single
> object covering a lot of building parts), you can "hack"
> around the proposal's limitation by using extra building
> parts for the roof elements in question (or single roof)
> that lack a building level and only account for the resp.
> roof levels.

good point


btw.: there's only one aspect of the simple building model which I really
detest: the way building:levels in defined for buildings that have
"missing" levels. IMHO it should express the number of building levels
(like it says), not be a partial information where you have to subtract
building:min_level to get the actual building levels number. ...and in case
there's a "bridge building" like in the example:
https://wiki.openstreetmap.org/wiki/File:Minlevel.svg the suggestion should
really be to use "min_height", as it will often not be clear to which
building or floor_height building:min_level refers to (the (existing)
levels of the object that has this tag, the left or the right building, or
a "standard height"?)
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