Not at all.<div>The change has already been committed to the development version.</div><div><br></div><div>giovanni</div><br><div class="gmail_quote">2012/4/6 blavet <span dir="ltr"><<a href="mailto:didier.blavet@ird.fr">didier.blavet@ird.fr</a>></span><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><u></u>
<div text="#000000" bgcolor="#ffffff">
Thank you very much for this very fast and efficient diagnosis<br>
<br>
Best regards<br>
<br>
Didier Blavet<br>
<br>
Le 06/04/2012 12:01, G. Allegri a écrit :
<blockquote type="cite">Probably I've found the bug.
<div>In Qgis the semi-minor axis of the ellipsoid is calculated with:</div>
<div><br>
</div>
<div>b = a - (f/a)</div>
<div><br>
</div>
<div>where </div>
<div>b = semi-minor axis</div>
<div>a = semi-majot axis</div>
<div>f = inverse flattening</div>
<div><br>
</div>
<div>while it should be:</div>
<div><br>
</div>
<div>b = a - (a/f)</div>
<div><br>
</div>
<div><br>
</div>
<div>In Qgis the WGS84 semi-minor axis is 6378136,xxx</div>
<div>while it should be 6356752.xxx</div>
<div><br>
</div>
<div>giovanni</div>
<div><br>
</div>
<div><br>
</div>
<div><br>
</div>
<div><br>
<br>
<div class="gmail_quote">2012/4/6 G. Allegri <span dir="ltr"><<a href="mailto:giohappy@gmail.com" target="_blank">giohappy@gmail.com</a>></span><br>
<blockquote class="gmail_quote" style="border-left:1px solid rgb(204,204,204);margin:0pt 0pt 0pt 0.8ex;padding-left:1ex">
<div><span>AFAICS, the Qgis formula [1] to calculate
distances on ellipssoid is Vincenty's.</span>
<div>I've reproduced it for the first set of points and I can
confirm tha QGis gives 540.9973919726176 m</div>
<div><br>
</div>
<div>The online Vincenty calculator [2] gives 540.045 m</div>
<div><br>
</div>
<div>I suppose it's a rounding issue. </div>
<div>I will investigate it more...</div>
<div><br>
</div>
<div>giovanni</div>
<div><br>
<div><br>
</div>
<div>[1] <a href="http://trac.osgeo.org/qgis/browser/trunk/qgis/src/core/qgsdistancearea.cpp#L540" style="color:rgb(17,85,204)" target="_blank">http://trac.osgeo.org/qgis/browser/trunk/qgis/src/core/qgsdistancearea.cpp#L540</a> </div>
<div>[2] <a href="http://www.movable-type.co.uk/scripts/latlong-vincenty.html" style="color:rgb(17,85,204)" target="_blank">http://www.movable-type.co.uk/scripts/latlong-vincenty.html</a> </div>
</div>
<br>
</div>
<div class="gmail_quote">2012/4/6 blavet <span dir="ltr"><<a href="mailto:didier.blavet@ird.fr" target="_blank">didier.blavet@ird.fr</a>></span><br>
<blockquote class="gmail_quote" style="border-left:1px solid rgb(204,204,204);margin:0pt 0pt 0pt 0.8ex;padding-left:1ex">
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<div>-- <br>
<p style="margin-bottom:0cm"><font>_______________________________________________________________________________________</font></p>
<p style="margin-bottom:0cm"><font color="#008000"><font><b>Didier
B</b><b>lavet</b> </font></font>
</p>
<p style="margin-bottom:0cm"><font color="#000000"><font>Institut
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Recherche pour le Développement - IRD (<font color="#0000ff"><a href="http://www.ird.fr" target="_blank">http://www.ird.fr</a></font>)
</font></font></p>
<p style="margin-bottom:0cm"><font color="#000000"><font>UMR
Eco&Sols - Ecologie Fonctionnelle & Biogéochimie des Sols &
Agroécosystèmes </font></font>
</p>
<p style="margin-bottom:0cm"><font color="#000000"><font>(Montpellier
SupAgro-CIRAD-INRA-IRD)
(<font color="#0000ff"><a href="http://www.montpellier.inra.fr/ecosols" target="_blank">http://www.montpellier.inra.fr/ecosols</a></font><span style="font-style:normal">)</span></font></font></p>
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