[OSM-dev] determining the boundaries of cities?

[Peter Wendorff]

Hi Ákos.
I fear, we don't have that distinction, as it's not that clearly 
separatable:

Am 31.05.2012 09:15, schrieb Ákos Maróy:
>  for example when you drive on the road, you encounter a city limit 
> sign at the end of the city, and then afterwards you can drive with 
> different speed limits. 
In Germany the speed limit is the case by default, but in the city there 
may be different limit signs even increasing that.
One problem with this kind of "boundary" is, that it's only defined 
along streets, not on every small way and not in between.
One proposal to tag this is [1], referring not to the boundary, but to 
the points on the boundary where the city limit starts.

On the other hand there's [2], the maxspeed-key and the addition as 
source:maxspeed, which can be source:maxspeed=DE:urban and so on.

> also, within city limits, there are certain services the city 
> provides, like a residential road, water, electricity, gas, public 
> lighting, etc. outside of the city this is not provided. this is the 
> city limit I'm looking for 
In Germany this distinction is not true.
As far as I know this kind of public infrastructure is provided in areas 
that are planned to be used for a specific purpose like building houses 
or sth. like that.
There may be areas in the rural area where no power is provided, but 
other places may have power, e.g. because there's a farm or a fuel station.
On the other hand there may be parts in cities, that have not (yet) 
water supply because there's nothing built or going to be built yet.
>> Therefore perhaps the area with continuous cover of buildings is the
>> target, which corresponds to the reality in the sense of "realizing" it
>> if you go out.
> my hope was that landuse="residential" would show this aspect, but it
> doesn't :(
landuse=residential should match areas mainly used for residenting - 
houses to live in.
parts of cities clearly are at least:
landuse=commercial
landuse=cemetery
landuse=brownfield
landuse=construction
landuse=garages
landuse=greenfield
landuse=industrial
landuse=railway
landuse=retail
landuse=village_green

but not the other way around, e.g.:
there may be landuse=construction that does not belong to cities.
there may be landuse=railway outside of cities
> what is the intended way of showing what is an urban area, and what is
> rural?
I don't think we have something like that, as - see above - the big 
question here remains: what is an urban area and what is a rural one?

regards
Peter

[1] http://wiki.openstreetmap.org/wiki/Tag:traffic_sign%3Dcity_limit
[2] http://wiki.openstreetmap.org/wiki/Maxspeed