Solution: >Q/Dk7 #
The plastic material with the rough diffusing surface can be modeled in } #J/fa9
!
TracePro, but as two separate properties (select Define/EditPropertyData). ,b d_:
N;d] 14|
MATERIAL PROPERTY (mOtU8 e
A TracePro Material Property can be created, and the index of refraction of S3#>9k;p
the material is entered here, as well as an absorption coefficient if it is [Zrr)8A
known (this would be for absorption losses just from propogating through a ;`Z{7' ^U
given thickness of a clear polished sample of the material, unrelated to the %C0Dw\A*:
diffusing surface finish. Entering zero for the absorption coefficient is @ 7u 0v
propobly a reasonable estimate for a transparent material. i?/qY&~
=v\.h=~~
The Material Property is applied to the Object (Define/Apply Properties). K'xV;r7Nt
O2+ 6st
SURFACE PROPERTY 5N]" ~w*
A TracePro Surface Property can specify 5 possible outcomes for light incident HsWk*L `y
on a surface - Specular Transmission, Specular Reflection, Scattered /efUj kP
Transmission (BTDF). Scattered Reflection (BRDF), and Absorption. i@q&5;%%
>ef6{URy<
For your property, I expect that Specular Transmission, Specular Reflection, Fcx&hj1gQ
and Absorption would all be 0, leaving only Scattered Transmission (BTDF). [K Qi.u
Scattered Reflection (BRDF). BTDF and BRDF are controlled by 3 coefficients - &[9709 (=
A, B, and g. For an initial estimate, I would suggest entering BTDF(g) = t:S+%u U
BRDF(g) = 0, which defines a Lambertian dsitribution. #G3<7PK
{I ((p_
The challenge is to determine the proper ratio of Transmittance vs IgzQr >
Reflectance. You can enter a value for BRDF(A) and then use the Solve For E$e5^G9
feature to solve for BTDF, and the editor will display the resulting xLE)/}y_7H
Integrated BTDF and Integrated BRDF values. You want these to sum to 1, and rjP/l6
~'
to have a ratio that matches the behavior of your surface. If the ratio of T NlqImM=r,
vs R is dependent on the Incidence Angle, you can use the Add button in the sT.ss$HY9,
property to add Incidence ANgles to the table, and then define the BTDF and iCoX& "l b
BRDF separately for each incidence angle.
