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Archiver > TMG > 2011-02 > 1297873745


From: Richard Damon <>
Subject: Re: [TMG] Real world UTM example, SHORT
Date: Wed, 16 Feb 2011 11:29:05 -0500
References: <6.2.3.4.2.20110214225300.03b9b3b0@pop.earthlink.net> <4D5A84DC.8050509@sprynet.com><6.2.3.4.2.20110215210708.03b87c60@pop.earthlink.net><4D5BF249.8030905@sprynet.com>
In-Reply-To: <4D5BF249.8030905@sprynet.com>


On Wed, 16 Feb 2011 09:50:33 -0600, "Darrell A. Martin"
<> wrote:

>Greetings:
>
>Here is a real world example of the zone boundary "gotcha" in UTM.
>
>There is a medium size graveyard on Littleton Road in North Monroe, New
>Hampshire. (I have ancestors who lived in the area.) The west and north
>corners of the graveyard are on the road, roughly 100 meters apart
>SW-NE. Here are the UTM coordinates as given by Google Earth (WGS84 datum).
>
>West corner: 18T 739228m E, 4910293m N
>North corner: 19T 260741m E, 4910357m N
>
>Note the difference in eastings. The numbers do not even seem to relate.
>
>I would say "I rest my case", but you know me better than that. See my
>"tedious" message for details.
>
>Darrell

This shows one of the issues with UTM, note that the first number
field changed from 18 to 19, that means that the coordinates are on
different Zone, and the mathematical relationship in the coordinates
is broken.UTM divides the earth into 60 zones of 6 degrees of
longitude.

If you really want to use UTM in cases like this, you need to use a
map that provides both zone markings near the overlap (near being
based on how far of a distance you need to be able to measure with the
eastings/northings).

Richard Damon
http://genealogy.damon-family.org

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