[Proj] Re: Discovery: libproj4 stmerc = French
Gauss-Laborde projection
strebe at aol.com
strebe at aol.com
Wed Jun 14 13:50:37 EDT 2006
Hm. I didn't know about that web page. Obviously it's wrong -- for some
reason "p" appears in several different roles. I tend to think that's
an error in conversion to a web page. (I see that the entire blurb is a
single graphic, not HTML mark-up.) Certainly he's been pedantic and
precise in all his communications with me.
The p/2 exponent should read (e/2), where e is the eccentricity.
Use some other variable (perhaps p') in place of p in "Then, the
complex variable tan (p/2) can be obtained..." and "...yields the
argument p..."
Regards,
-- daan Strebe
-----Original Message-----
From: Gerald I. Evenden <gerald.evenden at verizon.net>
To: PROJ.4 and general Projections Discussions <proj at lists.maptools.org>
Sent: Wed, 14 Jun 2006 11:42:40 -0400
Subject: Re: [Proj] Re: Discovery: libproj4 stmerc = French
Gauss-Laborde projection
On Wednesday 14 June 2006 1:12 am, Strebe at aol.com wrote:
> You might contact Dr. David E. Wallis. He devised a much simpler
method
> than Dozier's. I've implemented it for the full-ellipsoid. You can
see a
> plot of an earth-like ellipsoid here:
>
>
http://mapthematics.com/Projection%20Images/Cylindrical/Transverse%20Merc
at
>or. GIF
>
> The method works for arbitrary eccentricities. Contact me privately if
> you're interested. Since it is Dr. Wallis's invention, I'll put you in
> contact with him.
Dr. Wells has a web page relating to the projection:
http://www.wallisphd.com/mercator.htm
that a Google search on his name will return. Found this site several
years
ago during a previous discussion about tmerc. To me, the web page
appears
unchanged and the "Publication Pending" notice at the top is certainly
taking
a long time.
I should post him a letter for further information and follow up with a
phone
call if no response.
The description of the equation present does not make much sense unless
what
looks like p in the tan term is not the p described as colatitude.
Again,
the first line says p,lambda is the colatitude and longitude yet the
description following the formula talks about a p for the Elliptic
Integral
of the second kind.
I must be missing something.
--
Jerry and the low-riders: Daisy Mae and Joshua
"Cogito cogito ergo cogito sum"
Ambrose Bierce, The Devil's Dictionary
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