Photometric Functions

This is only active if there is not an atmosphere; the Delta-Eddington model used to handle atmospheric opacity includes the assumption that the surface is Lambertian.

In some later version when more input parameters are available, it is intended to be allowed when there is an atmosphere.

Photometric function include Lambertian, Lommel-Seeliger, Kheim / Lunar-Like, Minnaert (see V34UG.pdf for formalism).

Users can set the photometric function by setting PhotoFunc:

Minnaert

PhotoFunc = [-1.-0.[
ALBEDO = [0-1]

with Minnaert coefficient = abs(PhotoFunc)

Kheim / Lunar-like

PhotoFunc = ]0.-1.[
ALBEDO = [0.-1.]

For Lunar-like (Kheim=0.25, Vasavada=0.375).

Lambert

PhotoFunc = 2
ALBEDO = [0.-1.]

Lommel-Seeliger

PhotoFunc = 3
ALBEDO = [0.-1.]