[OSRS-PROJ] Pseudo X/Y values, forward and reverse

[Clifford J Mugnier]

Gerald,

In general I am inclined to agree.  However, there WAS a valid reasons for
zone extensions when computing the European Datum of 1950, but I have not
seen a valid reason since.  As a general rule, everytime I have seen
someone with such a need, I felt that it was because they were not familiar
with other projections enough to realize that there are easier ways to skin
such a cat.

I've done such whopping extensions just to see for myself if it could be
done, and after satisfying myself that it could be done; I have never had
an occasion to do it.  (Other than to talk about it as a purely academic
exercise).

There's a very big problem with doing a zone extention.  Even when you
program all of those derivatives and you can do it, nobody else will be
able to do it unless they have the exact same extreme extension running in
their own software.  You won't be able to share the data set!

Moral:  Be careful what you wish for ... you may get your wish!

Cliff Mugnier
LOUISIANA STATE UNIVERSITY

I am very sorry, but I consider the current thread nonsense.
Anyone carrying the TM projection ellipsoid projection beyond
3.5 degrees of the CM is up to no good.  UTM does not require
greater extension and the scale factor beyone 3.5 degrees
makes it useless as an accurate conformal projection.

Adding factors to the equations is merely a waste of computer
time.

'Nuff said.

On Fri, 2003-01-31 at 00:22, Clifford J Mugnier wrote:
>
> William,
>
> Yes, it counts in BOTH directions.  I'm currently writing the chapter on
> "Object Space Coordinate Systems" for the new 5th edition of the "Manual
of
> Photogrammetry," and I'm including up to the 7th derivative in both
direct
> and inverse transformations.  Why weren't greater expansions included
into
> PROJ4?  It's not a topic of general interest in cartography.
Cartographers
> generally ignore such things, including the late John P. Snyder.  John
was
> only interested in what was germain to the U.S. Geological Survey and the
> scales of maps that they produced.  John was never interested in geodetic
> stuff.  John avoided datums and such things.
...

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