Next message: Lu Abel: "Re: Azimuth and Declination formulae"
See also <http://gauss.gge.unb.ca/papers.pdf/gpsworld.february98.pdf>.
-- Richard Langley
On Tue, 19 Jul 2005, Jared Sherman wrote:
>Robert-
> <Theoretically, if one wishes to find one's
>latitude in degrees and minutes, all one has to do is divide the northing
>reference by 1852, then by 60, to come up with the right answer, but this is
>not the case. >
> I think the key word is "theoretically".
>
>AS I understand it, UTM is based on a perfect cylinder, a Mercator
>Projection, for the bulk of the world (outside the polar areas) and given
>that distorted projection, your theoretical conversion works perfectly well.
>But from the references online it seems that the system is NOT designed to
>be converted that way. Rather, the linear mileage (meterage?) is marked off
>on each topo quad, and you are supposed to either draw on the quad or use an
>overlay on it. The primary purpose is military, i.e. artillery, where maps
>will be distributed and the only question is how to tell the big guns
>exactly where you are on the map that you were given. UTM works very well
>for that, or for anything else where you are using paper quads.
>
>See http://erg.usgs.gov/isb/pubs/factsheets/fs07701.html
>and http://ask.usgs.gov/ where the USGS provides PHONE and email contacts
>for folks to ask questions.
>
>I know there are conversion utilities for computer use, but I suspect they
>are either referencing offset tables, or counting distance and accounting
>for the distorted globe. Not something you'd want to do by hand.
>
>I'll let you ask the prime authority directly--I know UTM has become popular
>with hikers, but I can work with degrees and have had no need or use for
>UTM.
>
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Richard B. Langley E-mail:
Geodetic Research Laboratory Web: http://www.unb.ca/GGE/
Dept. of Geodesy and Geomatics Engineering Phone: +1 506 453-5142
University of New Brunswick Fax: +1 506 453-4943
Fredericton, N.B., Canada E3B 5A3
Fredericton? Where's that? See: http://www.city.fredericton.nb.ca/
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