[Talk-us] Specifications (was: Bay Area trailer parks: "hamlet" ? Also neighborhoods & cities)

Alan Brown adbrown1967 at yahoo.com
Fri Nov 28 21:10:58 GMT 2008


In commercial data,  a category called hamlet is use dfor either neighborhoods, or small unincorporated settlements.  I've used them for neighborhoods in OSM mostly because I want to see them rendered - while it would be better to model them with descriptive names.  (Formal point-of-interest - "city centers" - all fall into the same category, but have different "population classes".  It's nearly identical to the module used for "place" point features, although population ranges are formally set for each place type.  There's also ways to flag is something is a national capitol, state capitol, or county seat.)

A lot of the discussion held here came up years ago when they designed the GDF specification - (Geographic Data Files).   This is an exchange format. A lot of that specification has to with the format of the ascii file - which is irrelevant to our discussion - but it also deals with features types and categories.  This is the format that various navigation systems and online map companies receive before converting it into their own proprietary access format.

Here's a short wikipedia summary:

http://en.wikipedia.org/wiki/Geographic_Data_Files

Here's a link to an old version of the specification:

http://www.ertico.com/en/links/links/gdf_-_geographic_data_files.htm

This version (3.0) came out 13 years ago.  It's since been significantly enhanced - both by ISO, and by Tele Atlas and NAVTEQ.  The enhancements add a lot of subtlety, particularly to POI categories.  The unfortunate thing is that Tele Atlas and NAVTEQ versions are not 100% compatible with each other, and no one fully complies with the ISO standard.  The attributes of the 3.0 spec are largely followed.

The Annexes are probably the best place to start, and it contains an appendix of feature categories - while chapters 5, 6, and 7 describe features in detail.

While this spec doesn't resolve the "hamlet vs. neighborhood" issue - and it doesn't flesh out details for bicycle routes and paths - it has a lot of sophistication for things like different types of highway ramps, turn restrictions, dealing with road connectivity, etc., etc.  I know they want to give people the ability to tag things in new ways, but if OSM has aspirations of becoming a routable database, things have to fall into predictable categories for software to interpret them.

-Alan




 



________________________________
From: Scott Atwood <scott.roy.atwood at gmail.com>
To: Michal Migurski <mike at stamen.com>
Cc: talk-us at openstreetmap.org
Sent: Friday, November 28, 2008 12:25:38 PM
Subject: Re: [Talk-us] Bay Area trailer parks: "hamlet" ? Also neighborhoods & cities


On Fri, Nov 28, 2008 at 12:13 PM, Michal Migurski <mike at stamen.com> wrote:

Hi,

There are a large number of mobile home / trailer parks mapped in San
Jose, Santa Clara, and other parts of the South Bay. They're tagged
place=hamlet, and I'm wondering if there's a better way to identify
them? Beej71, if you're on this list I think a lot of these came from
you.

Examples here:
       http://www.openstreetmap.org/?lat=37.3995&lon=-122.01521&zoom=15&layers=B000FTFT
       http://www.openstreetmap.org/?lat=37.37096&lon=-121.89402&zoom=16&layers=B000FTF

"Hamlet" is supposed to be "defined by national/state/provincial
government" yet these aren't really defined by anyone except their
owners. I personally view them as generally equivalent to named
apartment complexes, and therefore not a place. May I suggest that
they be redrawn as landuse=residential areas, with names defined?

On a related topic, I'm also wondering how to handle parts of cities
that are "places" or neighborhoods yet not administratively distinct,
e.g. "West Oakland" (Oakland), "The Mission" (SF), etc. Would
place=neighborhood make sense here?

This part of West Oakland with two named apartment complexes (all
place=hamlet) illustrates what I mean:
       http://www.openstreetmap.org/?lat=37.8096&lon=-122.29504&zoom=16&layers=B000FTF

I think people (including me) have been using/misusing place=hamlet for places like neighborboods which have variable official status because there isn't really a good alternative.   I think there is a need for place=neighborhood, or something like it.  Whatever we come up with ought to be a solution that handles both the  traditional, informal notion of a neighborhood, which tends to be relatively small and often has nebulous borders, as well as more formal notions like the districts of Berlin, or the arrondissements of Paris with official status and well defined borders.


-Scott

-- 
Scott Atwood

Cycle tracks will abound in Utopia.  ~H.G. Wells
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