in the material editor, there is an option to "Make diffuse"
surface.. which translates surface reflectance to ward brdf
i believe the conversion is off by a factor of (1/PI). when
supplying a diffuse weight of 1.0, it results in a 100%
reflector in DIRSIG radiometry.. however, the wizard
in the GUI lets the user specify a reflectance value of 1.0
with the "make diffuse" button which it incorrectly translates
to a value of 1/PI = 0.318
Adam and I will check this out. My guess is that Niek didn't understand the Ward BRDF inputs.
I verified that the diffuse reflectance was being scaled by Pi in both the optical property and the material editor. I've removed the Pi scale in mat_edit so that the diffuse weight that it provides is consistent with the parametrization of the Ward BRDF model that we use.
I am assuming Adam's fix resolved this.