[Proj] Distance between pair of lat / lons

[Finn, Michael]

Good point!!

Thanks for sharing.


On Wed, Dec 26, 2012 at 3:38 PM, Clifford J Mugnier <cjmce at lsu.edu> wrote:

>
> *Legal Applications of Geodesic Formulae - Forensic Geodesy
> *.
>
> I do a great deal of consulting work for Attorneys as an Expert Witness,
> primarily with respect to Photogrammetry.  On occasion, I am asked to
> compute distances for submission in pleas for Summary Judgements.
>
>
>
> When I use ellipsoidal geodesics (normally the inverse case), I always use
> whatever is published by the United States National Geodetic Survey.
> Irregardless of the accuracy returned (which is quite good for several
> hundred miles/kilometers); it is what is legally considered as the
> "National Standard" recognized by *our* national U.S. government.
>
>
>
> Keep that in mind when doing such calculations in *your* country of
> residence; supreme accuracy is not as important as legal accuracy.
>
>
>
> Cliff Mugnier
>
> LOUISIANA STATE UNIVERSITY
>
>
>
> ________________________________________
> From: proj-bounces at lists.maptools.org [proj-bounces at lists.maptools.org]
> on behalf of Charles Karney [charles.karney at sri.com]
> Sent: Wednesday, December 26, 2012 3:16 PM
> To: proj at lists.maptools.org
> Subject: Re: [Proj] Distance between pair of lat / lons
>
> On 12/25/2012 11:46 AM, Jayesh Chaudhary wrote:
> > Folks,
> >
> > We have been using GeoographicLib and it had a convenient function to
> > calculate distance between two points with an error in the range of nm.
> > I am familiar with PROJ4 but I don't see any such function in PROJ4. We
> > do care about accuracy and therefore I am not willing to use simple
> > methods that consider earth as perfect to compute such distance.
> >
> > Please let me know if there is such functionality exists in PROJ4.
> >
> > Thanks
>
>
> The geod program in proj.4 version 4.8.0 is based on the work of Thomas
> (1970).  The accuracy of this method is limited and the inverse method
> fails for nearly antipodal points.
>
> In the next(?) version of proj.4, geod will use the geodesic routines
> from GeographicLib which cures the defects in Thomas' method.
>
> I hope that this version will also add the geodesic routines in the
> proj.4 library so that you can incorporate geodesic calculations into
> any code which links against proj.4.
>
> --
> 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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