RS : ViewRadius and FOV

Hi All,

I am trying to calculate FOV (Field of View) for any given viewport. I was successful with Perspective projections since I can use formula based on lens length and viewport aspect ratio. However, it does not work in Parallel views as the values returned by Rhino.ViewRadius don’t return correct results with that formula.
So I was wondering does anyone know what the view radius actually shows, and is this value related to FOV ?




OK, I think I can answer my own question - the Parallel view radius is basically the half-length of the shorter edge of frustum (gets flipped on vertically-proportioned views). I think that should be enough info for FOV calculations.