[Tagging] Consolidating tags for building attributes

Tobias Knerr osm at tobias-knerr.de
Fri Aug 23 17:21:16 UTC 2013

Hello Vivien,

I develop a 3D renderer working with OSM data, so I will look at your
questions based on that background.

Case A: roof:material vs. building:roof

The preferred key from 3D rendering documentation is roof:material
because, as you guessed, it clearly differentiates this attribute from
roof:shape. Based on just the wording of the key, building:roof could be
either - so you would have to look it up.

Case B: building:walls vs. building:material

I'm not sure what building:walls means exactly, I'm not using that tag
for rendering so far. But I can clarify the intention with
building:material: It's supposed to represent the outer material as seen
while mapping on-the-ground. Therefore, "plaster" is a valid value for
building:material because that's the outermost layer, even though the
entire wall is not made from plaster. If building:walls has the same
meaning, then I prefer building:material for the same reason as in Case A.

Case C: building vs. building:use

I have to agree with you here, the values used for the building key are
quite chaotic. But from the original intention as I remember it, I do
not think that the two things have the same meaning. For example, a
commonly cited example is that a church building which is no longer used
as a church and is now a museum (but still looks like a typical church)
would be tagged building=church + amenity=museum.

Personally, I only use a few hand-picked values from the building key
that have a rather clear meaning.

As for Case D and the other suggested keys, these are new or seem
unrelated to 3D rendering. However, I'm not sure about the exact meaning
of your suggested shape:elevation?


On 23.08.2013 18:22, Vivien Deparday wrote:
> Hi all,
> The OpenDRI project has been doing some work in Nepal and Sri Lanka to
> trace building footprints and to enter attribute data about the
> buildings. We are looking to get feedback from the tagging and HOT
> mailing list on the building presets that we are using and we would like
> to consolidate them with the HDM preset [1] and with the rest of the
> work done by HOT (e.g. in Indonesia [2]) to make sure it is consistent
> to use it with InaSafe [3] or for 3D Modeling [4] or any other applications.
> The presets developed by OpenDRI so far are Nepal [5] and Sri Lanka [6].
> The Nepal presets already received a couple comments from the tagging
> list that were applied.
> 1. We have been using 3D building guidelines (although they have a few
> contradictory elements), taginfo statistics and looked at a lot of
> tagging guidelines on the OSM wiki to create the keys and values but we
> didn't really find one general guideline for creating new tags so we
> would welcome any feedback on the presets [5] and [6].
> 2. There are a couple discrepancies:
> Case A:
> For the roof material, these keys have been used about the same number
> of times:
> In wiki gbothuidelines: roof:material= 
> or
> In HDM or Indonesia: building:roof=
> It seems like the first option would be better? because it allows to
> differentiate with roof:shape ?
> Case B:
> For wall material (different from building structure)
> In Indonesia: building:walls=
> or
> In HDM presets: building:material=
> building:material is more widely used or do the two tags are meant to be
> different?
> Case C:
> For building usage,
> building=
> building:use= 
> I am not sure what is the best between these two or do they have
> different goal/usage? building= seem to be a mix of usage, amenity type,
> structure type.
> Case D:
> capacity:persons=
> occupants=
> I suppose they represents two different things: full capacity of a
> building vs actual occupancy ?
> Some other tags that could be added to the HDM:
> building:structure
> roof:shape
> shape:plan
> shape:elevation
> If there is some kind of agreement I can create a pull request on the
> HDM presets and add some of the new tags we are using too. The detailed
> information about the new tags used in the presets will also be added to
> pages on the wiki.
> Cheers,
> Vivien
> [1] _http://wiki.openstreetmap.org/wiki/Humanitarian_OSM_Tags/HDM_preset#Building_digitizing_ 
> [2] _https://github.com/hotosm/hot-indo/blob/master/bpbd_presets.xml_ 
> [3] _http://inasafe.org/contents.html_ 
> [4] _http://wiki.openstreetmap.org/wiki/Simple_3D_buildings_ 
> [5] _http://visualtags.hotosm.org/collection/10_  (2 notes: the source
> tag will be removed from the presets and put on the changesets,
> building:start_date => start_date)
> [6] _https://www.dropbox.com/s/50blzkwmvxmbbw6/sri_lanka_presets.xml_
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