[PROJ] How does proj deal with ellipsoid with respect to reprojection

[DeTracey, Brendan]

 Even and Martin. Thanks so much for your replies. Stay safe my friends!


From: PROJ [proj-bounces at lists.osgeo.org] on behalf of Martin Desruisseaux [martin.desruisseaux at geomatys.com]

Sent: March 28, 2020 1:02 PM

To: proj at lists.osgeo.org

Subject: Re: [PROJ] How does proj deal with ellipsoid with respect to reprojection







Le 28/03/2020 à 16:30, Even Rouault a écrit :



<!--
p, li
	{white-space:pre-w}
-->
And given that the implementation of gnomonic is for a sphere only, the flattening of WGS84 is ignored. So you'll get the same result as if it was a sphere of radius 6378137 metres.

Just a little note in case it may be considered worth to apply: in situations where spherical formulas are used with an ellipsoid, EPSG approach is often to use the authalic radius (the radius of a sphere of same surface than the ellipsoid) instead than
 the semi-major axis length.
https://en.wikipedia.org/wiki/Earth_radius#Authalic_radius
    Martin