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

[DeTracey, Brendan]

Hi,

I am using a gnomonic projection for point in polygon testing. The transformation is:

projinfo -s EPSG:4326 -t ' +type=crs +ellps=WGS84  +datum=WGS84 +proj=gnom +lat_0=61.39107201212929 +lon_0=-58.56360634793518'

Will transformed great circles still be straight lines? Or does the fact that my source and target ellipse/datum are the same mean the gnomonic projection has the WGS4 coordinates passed directly to it? My confusion comes from gnomonic only being defined for a sphere, not an ellipsoid. 

Any clarification would be appreciated.

Thanks,
Brendan