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Archiver > TMG > 2011-02 > 1297874742


From: "Darrell A. Martin" <>
Subject: Re: [TMG] Real world UTM example, SHORT
Date: Wed, 16 Feb 2011 10:45:43 -0600
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><fcunl6pflffuquvfo817snd3s9rsiohspi@4ax.com>
In-Reply-To: <fcunl6pflffuquvfo817snd3s9rsiohspi@4ax.com>


On 2/16/2011 10:29 AM, Richard Damon wrote:
> 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

Richard:

For current use by "experts", like orienteering, I agree that the tools
to deal with UTM zone boundaries exist. But when storing information for
future users, or when providing information for casual users of
coordinates (such as cemetery investigations by genealogists -- "I have
my GPS and a highway map, what are you talking about?"), the complexity
is a significant problem, in my opinion.

Darrell


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