[OSM-talk] Underground / hovering buildings

[andrzej zaborowski]

On 15 February 2011 23:11, Nathan Edgars II <neroute2 en gmail.com> wrote:
> Jacek Konieczny wrote:
>>
>> layer=-1 tells only that the thing is under layer=0 and over layer=-2,
>> nothing in relation to 'ground level' (some rivers or roads may have
>> layer=-1 or layer=1 on most of its length).
>>
> No, ground level is layer 0. A nonzero layer on a ground-level feature is an
> error.

That's never been a rule in OSM.  However, since the choice of the
level=0 feature is arbitrary there's nothing wrong with actually
assuming (as a producer, not consumer) 0 to mean the perceived ground
level and I usually do that.  That way I can at least re-tag my work
easily once there's a popular levels_above_ground tag.

Cheers