[Proj] The area of a rhumb line polygon

Charles Karney charles.karney at sri.com
Tue Dec 16 09:13:23 EST 2014


Only the toolbox version requires R2014b.  The Matlab release I used was
R2013a and it works with Octave too.  Just click on "Download Zip".

GeographicLib already works with the World Magnetic Model 2015.  You can
download the model from

   https://sf.net/projects/geographiclib/files/magnetic-distrib/

and you are good to go.  Just specify "-n wmm2015" to the MagneticField
utility.  (This will be the default for GeographicLib 1.40 which I will
be releasing later this week.)

While on the subject of great ellipses, I provide a critique of some
papers which advocate great ellipses for the purposes of navigation at

   http://geographiclib.sf.net/html/greatellipse.html#gevsgeodesic

   --Charles

On 2014-12-16 09:01, Noel Zinn (cc) wrote:
> Thanks for the Matlab versions, Charles.  Why R2014b?  (I'm still running
> R2014a, but planning an upgrade to R2015a, which will include the new World
> Magnetic Model.)
> Noel
>
> Noel Zinn, Principal, Hydrometronics LLC
> +1-832-539-1472 (office), +1-281-221-0051 (cell)
> noel.zinn at hydrometronics.com (email)
> http://www.hydrometronics.com (website)
>
> -----Original Message-----
> From: Charles Karney
> Sent: Tuesday, December 16, 2014 7:14 AM
> To: PROJ.4 and general Projections Discussions
> Subject: [Proj] The area of a rhumb line polygon
>
> The calculation of the area of a geodesic polygon has been included in
> GeographicLib since v1.4 (2010-09).
>
> In the latest version v1.39, I've also included the equivalent
> calculation when the edges of the polygon are rhumb lines.  The
> formulation is given in
>
>     http://geographiclib.sf.net/html/rhumb.html#rhumbarea
>
> and the online planimeter
>
>     http://geographiclib.sf.net/cgi-bin/Planimeter
>
> implements this area calculation.  I've also worked out the area when
> the edges are great ellipses.  For the formulation, see
>
>     http://geographiclib.sf.net/html/greatellipse.html#gearea
>
> An implementation is included in the Matlab package
>
>     http://www.mathworks.com/matlabcentral/fileexchange/47898
>
> Comments are welcome.
>
>     --Charles
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-- 
Charles Karney <charles.karney at sri.com>
SRI International, Princeton, NJ 08543-5300

Tel: +1 609 734 2312
Fax: +1 609 734 2662


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