[uf-discuss] geo - accuracy of coordinates

Michael MD mdagn at spraci.com
Mon Oct 2 16:11:07 PDT 2006

>A center of a city may be fairly accurate, with the
>bounds of the city specified as a radius.

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
>        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!)

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

The radius idea could possibly be used but the radius itself would be
inaccurate. 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")

Maybe just something to describe "fuzzyness" is needed?

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