-------- Original Message --------
Subject: Re: City Centers criteria by Lat. Long.]
Date: Sun, 19 Dec 2004 00:06:39 GMT
From: [log in to unmask] <[log in to unmask]>
To: [log in to unmask]

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I think it varies...near where I grew up, there was a road sign,
"Pittsburgh 15."  That was 15 miles to the city line, not to downtown.
I've seen it the other way as well...As I recall, I-59 near Hattiesburg
has  a sign "New Orleans 75."  It's not the city line, but it's not the
CBD either.    I'm thinking that takes you to mile 240 or 242 on I-10,
maybe where it starts to get "urban."  Another possibility is that it's
"as the crow flies."

For those interested, there is a formula in the CRC manuals saying how
to compute the centroid of a triangle given its corners.  GIS doesn't do
real integration, of course...but if every polygon is decomposed as
triangles, then computing the centroid is easy.

So far as I know, there is no way to compute the composite medoid of a
set of disjoint polygons.

JMM