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

[Martin Desruisseaux]

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

> 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


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/proj/attachments/20200328/b1187786/attachment.html>