[Talk-us] Possible method for identifying major US cities

Peter Budny peterb at gatech.edu
Wed Oct 27 01:21:03 BST 2010


Phil! Gold <phil_g at pobox.com> writes:

> * Nathan Edgars II <neroute2 at gmail.com> [2010-10-25 21:39 -0400]:
>> I've done it in Florida. Here's the algorithm I used:
>> principal city of a Metropolitan Statistical Area: city
>> principal city of a Micropolitan Statistical Area: town
>> other incorporated municipality with population over 10,000: suburb
>> (these are all inside statistical areas)
>> other incorporated municipality with population under 10,000: village,
>> hamlet, or (in the case of Islandia) locality (according to the
>> cutoffs on http://wiki.openstreetmap.org/wiki/Key:place)
>> other unincorporated places: left alone for now
>
> I mostly like this, but I feel somewhat constrained by the place= values
> for some of this.  I went over the classifications that this would make in
> Maryland and agreed with most of it, except that I'd really like another
> value above place=city.  This algorithm would mark Arlington, VA;
> Alexandria, VA; Reston, VA; Bethesda, MD; Rockville, MD; Frederick MD; and
> Gaithersburg, MD as cities, in addition to Washington, DC.  That's pretty
> fair, considering those places' populations and economic importance, but
> DC should be ranked a step higher than the rest.  Likewise, it would make
> Baltimore and Towson both cities and, while making Towson a city is not
> unfair, Baltimore is far more important a place than Towson is.  (For one
> thing, people from other states are much more likely to have heard of
> Baltimore.)
>
> I've been thinking a lot about city importance since I read
> http://www.41latitude.com/post/1178194590/jaywalking and
> http://www.41latitude.com/post/400972984/most-important-cities-united-states .
> I think I'm mostly of the mind that OSM's basically four-tier system
> (city, town, village, hamlet) system isn't granular enough for properly
> indicating cities' importance relative to each other.  I think some of the
> general "importance" tagging ideas that have been floated might help with
> this.  If I have time, I might see about getting them on the proposal
> track actively, rather than languishing.

Martin and I had a discussion (was it on this list?) about this, and I
think we agreed that the place=* tag isn't really very helpful.  It's
just too coarse-grained, and it can't be tuned for producing different
types of maps.

The idea we started thinking about is to have tags (on the city node, or
way, or relation) that give a whole bunch of statistics that might be
relevant for determining how "important" a city is, which would
determine at what zoom level it shows up and how big its label should
be.

Not to say that the place=* tag should go away, but I'd like to see it
relegated to being nothing more than a 'suggestion' for less featureful
renderers.  Any serious map rendering ought to be more flexible than
just 4 arbitrary sizes of cities/towns assigned manually.

(My sole complaint about the idea, really, was that having tags in OSM
for information like population which could theoretically be culled from
other sources automatically is kind of redundant and thus
troublesome... except that we'd have to have so many data sources (one
per country, roughly) that it would be impossible to maintain.  So just
sticking it in tags and updating it manually/semi-automatically is
probably okay.)
-- 
Peter Budny  \
Georgia Tech  \
CS PhD student \



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