[Tagging] Rooftop parking -> new parking=rooftop value?

[Holger Jeromin]

johnw wrote on 11.11.2014 06:38:

> I’m not sure of other countries, but at least in the US, parking on
> top of retail structures is exceedingly rare - usually there are
> adjacent multi-story parking structures. It always seems that there
> is some kind of code or cost savings preventing it, always forcing it
> to be underground or lower level parking inside the building itself,
> which really isn’t mappable.

> In Japan, rooftop parking on multistory buildings (bottom floors are
> shops, and the roof is parking) is quite common.  sometimes there is
> more than one upper floor used for parking - it was such a surprise
> to find a 5 story Costco, with 2 bottom floors for the retail space,
> and the top 3 for car parking.

Ok, you want to have one way for the whole building. I dont think this
would work.

What differs a full 5 level multi-story parking and a
4 level parking on top of one shop level? Why use rooftop instead of
multi-story?
Where is the border when to use rooftop and when multi-story? Majority
of levels used not for parking?

Suppose a way with the tags:
building=yes
building:levels=5
amenity=parking
parking=rooftop
shop=department_store

How much of the building is the department_store, how much parking?
What about a amenity=school? we cannot reuse the amenity tag on the same
way.

I would suggest two overlapping ways:
building=yes
amenity=parking
parking=multi-story
building:levels=5
building:min_levels=2
layer=1

and
building=retail
building:levels=2
shop=department_store

If we have only the roof used, we could map it as surface with a
min_height and layer.

> I assume there is a need to create a new parking=rooftop or similar
> tag, which can then be used to create more accurate renderers
> (perhaps by also placing the parking=rooftop tag onto the
> service=parking isle service roads, so they are similarly
> (translucently?) rendered.

translucent should be IMO only indoor (aka tunnel) ways.

-- 
greetings
Holger