The Tissot's indicatrix of an Azimuthal Equidistant projection shows ellipses being stretched along latitudes.
How can I calculate the degree (amount) of this distortion? That is, what is the ratio of major axis to minor axis of a Tissot ellipse as a function of latitude (assuming the center of projection is the north pole)?
Edit: Found numerical values on the GIS help page.
Degrees from center Percentage of scale distortion along parallels 15 1.2 30 4.7 45 11.1 60 20.9 90 57
I can interpolate this well and get what I need. But would still be good to know what the analytical formula is. Feels like a function of
cos(latitude) since an Azimuthal Equidistant projects latitudes with linearly increasing distance from center instead of cosine.