On Oct 2, 2006, at 4:11 PM, Michael MD wrote:
Not really, if it's a large city...
Consider Birmingham, England, whose "centre" is far from being
equidistant to all points on its boundary - it's in "Ladywood" on this
map:
http://www.birmingham.gov.uk/wards
GeoRSS uses a "radius" element, which could be a uf class and would
specify in meters, kilometers, or miles (itself a discussion for
units). Or perhaps better would be a featuretypetag (again using
GeoRSS as a working case example) that can specify "city"
Or the capacity to describe a polygon...
In many cases the available data is just not accurate enough to be
able to
accurately describe a radius or polygon.
(if it were, it might be accurate enough for a street address too!)
Again, consider this URL:
http://flickr.com/map/?&tag=yankeestadium&fLat=40.828081&fLon=
-73.920821&zl=7
if it were expressed as a radius of 10km, I think it would do for Brum
as a whole.
Even with only city-level accuracy, lat/long data can still be very
useful,
but clearly I'd want to avoid having it end up being used to generate a
local street map that gives someone incorrect directions to get to a
street
address!
The radius idea could possibly be used but the radius itself would be
inaccurate.
That's fine - it's really an order-of-magnitude expression of detail.
I think the featuretype idea is probably better for this if
there can be a standard for the actual feature type names.
(but in GeoRSS it appears to be folksonomy-based so if data comes from
multiple sources, an application might need to look up some kind of
dictionary of commonly used terms just to work out that it's a "city")
Or, as in this example, it could be derived from the tag + geo
expressed by several people.
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