[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..."

-- 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 
> than Dozier's. I've implemented it for the full-ellipsoid. You can 
see a
> plot of an earth-like ellipsoid here:
>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:


that a Google search on his name will return.  Found this site several 
ago during a previous discussion about tmerc.  To me, the web page 
unchanged and the "Publication Pending" notice at the top is certainly 
a long time.

I should post him a letter for further information and follow up with a 
call if no response.

The description of the equation present does not make much sense unless 
looks like p in the tan term is not the p described as colatitude.  
the first line says p,lambda is the colatitude and longitude yet the
description following the formula talks about a p for the Elliptic 
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
Proj mailing list
Proj at lists.maptools.org

Check out AOL.com today. Breaking news, video search, pictures, email 
and IM. All on demand. Always Free.

More information about the Proj mailing list