[Tagging] levels and min_level (was Underground / hovering buildings)

M∡rtin Koppenhoefer dieterdreist at gmail.com
Fri Feb 18 17:52:34 GMT 2011

2011/2/18 Peter Wendorff <wendorff at uni-paderborn.de>:
>> In my opinion, the better choice would be to invent a new tag for
>> building parts, and map the entire building's outline as building=yes in
>> addition to the individual parts.

I would also like to see building parts, but I think that another
option instead of drawing another way for the "whole building" would
be to group those parts with a relation.

> Yes, it could be a good idea to invent a separate tag for building parts.
> I would appreciate that (and initially these issues are part of the reason
> why my proposal is not a proposed tagging scheme in the common sense of the
> proposal process).
> But one question is left here:
> What is the building outline you would like to map in future as
> building=yes, too?
> Is it (a) the "maximum size outline" as shown in aerial imagery?

yes, I guess that's an easy to map approach that would suit well

> Is it (b) the "on-ground-outline" a pedestrian would be able to go along?

no, this would in some cases be ridiculous (think of a
"mushroom"-building: the most parts would miss). If this is required
(in some cases there is indeed a huge benefit) I would use another

> Is it (c) the "maximum size outline" including underground parts not build
> up above ground - like bigger underground parking areas?

No, I would not extend this to underground parts (they would get their
own tagging and ways if necessary). Showing underground in a standard
map will be very confusing, because they will not be recognizable on
the ground and hence create a different shape in respect to what
people are used to see on the ground. (They are more confusing then

> Is (d) the building=yes a fallback for renderers not supporting the
> building_parts?

could be interpreted as such. Could also be a reduction for lower zoom
levels and renderings that focus less on building detail


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