[OSRS-PROJ] Re: Concerning calumny and the ellipsoidaltransverse Mercator

[Clifford J Mugnier]

Army Technical Manual TM 5-241-10 is the Official manual for zone
extentions of ±24º from the central meridian.  It is "kosher" UTM for
extending out for artillery fire control and/or datum computations.
(That's how European Datum 1950 was computed.)  It really DOES have
practical applications including using one zone for offshore mapping of the
entire Gulf of Mexico.

In the oil patch, there is a constant request for such a facility.  It just
becomes problemmatic if everyone does not use the same software.  Since
ESRI is so pervasive in the oil patch, it appears it will be warmly (and
widely) accepted.  Pun intended.

Cliff Mugnier
LOUISIANA STATE UNIVERSITY
--------------------------------------
On Sun, 2003-08-24 at 11:45, Clifford J Mugnier wrote:
>
>
> I gave a one-day seminar at the ESRI Annual Convention this past July on
> Grids and Datums.  Ms. Melita Kennedy, the staff Geodesist at ESRI,
> informed me that they have developed an iterative Transverse Mercator
> direct and inverse that will be implemented soon in ESRI projection
> engines.  She said it will do ±90º from the central meridian.  Ms.
Kennedy
> acknowledged that it was based on an obscure NOAA publication (Not NGS)
> published about 15 years ago in the form of a "C" program.

>From our continued boxing off group Strebe made the following
reference:

"Jeff Dozier, "Improved Algorithm for Calculation of UTM and
Geodetic Coordinates", NOAA Technical Reprot NESS 81"

Seems to fit Kennedy's statement.

> Breast beating and teeth gnashing aside, there are practical applications
> to using the Transverse Mercator in greater expansions from the central
> meridian than 3º for LARGE Scale topographic mapping, and there are a
> number of practical applications for ellipsoidal loxodromes in geodetic
> computations and LARGE scale mapping.

I recall that the UTM limit was spec'd at 3½° limit.  But it will go
to a larger extent without too much distortion.  Besides precision
needs drop off with smaller scale associated with larger extent.

I wonder why ESRI bothered as it seems to not be worth the effort
as an economic activity.  As you say, there's nothing the cadastral
world that has any use for it and it only confuses the issue.

<snip>

> Just because something appears to be a "two-man" discussion does not mean
> that others do not watch the "tennis match."
>
> Cliff Mugnier
> LOUISIANA STATE UNIVERSITY
<snip>
--
Gerald I. Evenden <gerald.evenden at verizon.net>

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