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<p><br>
<strong><u>Legal Applications of Geodesic Formulae - Forensic Geodesy<br>
</u></strong>.</p>
<p>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.</p>
<p> </p>
<p>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 <em>our</em> national U.S. government.</p>
<p> </p>
<p>Keep that in mind when doing such calculations in <em>your</em> country of residence; supreme accuracy is not as important as legal accuracy.</p>
<p> </p>
<p>Cliff Mugnier</p>
<p>LOUISIANA STATE UNIVERSITY</p>
<p> </p>
<p>________________________________________<br>
From: proj-bounces@lists.maptools.org [proj-bounces@lists.maptools.org] on behalf of Charles Karney [charles.karney@sri.com]<br>
Sent: Wednesday, December 26, 2012 3:16 PM<br>
To: proj@lists.maptools.org<br>
Subject: Re: [Proj] Distance between pair of lat / lons<br>
<br>
On 12/25/2012 11:46 AM, Jayesh Chaudhary wrote:<br>
> Folks,<br>
><br>
> We have been using GeoographicLib and it had a convenient function to<br>
> calculate distance between two points with an error in the range of nm.<br>
> I am familiar with PROJ4 but I don't see any such function in PROJ4. We<br>
> do care about accuracy and therefore I am not willing to use simple<br>
> methods that consider earth as perfect to compute such distance.<br>
><br>
> Please let me know if there is such functionality exists in PROJ4.<br>
><br>
> Thanks<br>
<br>
<br>
The geod program in proj.4 version 4.8.0 is based on the work of Thomas<br>
(1970). The accuracy of this method is limited and the inverse method<br>
fails for nearly antipodal points.<br>
<br>
In the next(?) version of proj.4, geod will use the geodesic routines<br>
from GeographicLib which cures the defects in Thomas' method.<br>
<br>
I hope that this version will also add the geodesic routines in the<br>
proj.4 library so that you can incorporate geodesic calculations into<br>
any code which links against proj.4.<br>
<br>
--<br>
Charles Karney <charles.karney@sri.com><br>
SRI International, Princeton, NJ 08543-5300<br>
<br>
Tel: +1 609 734 2312<br>
Fax: +1 609 734 2662<br>
<br>
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Proj mailing list<br>
Proj@lists.maptools.org<br>
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