Solution: V2oXg
The plastic material with the rough diffusing surface can be modeled in ., =\/ C<
TracePro, but as two separate properties (select Define/EditPropertyData). \N a
*-,jIaL;
MATERIAL PROPERTY l U8X{SV!
A TracePro Material Property can be created, and the index of refraction of FCIA8^}s
the material is entered here, as well as an absorption coefficient if it is njGZ#{"eC
known (this would be for absorption losses just from propogating through a a0)] W%F
given thickness of a clear polished sample of the material, unrelated to the q Oyo+hu
diffusing surface finish. Entering zero for the absorption coefficient is ;y]BXW&l&
propobly a reasonable estimate for a transparent material. S]g`Ds<
VK[`e[.C
The Material Property is applied to the Object (Define/Apply Properties). Aq,&p,m03
:TRhk.
SURFACE PROPERTY i~ITRi@
A TracePro Surface Property can specify 5 possible outcomes for light incident f l+dL#]
on a surface - Specular Transmission, Specular Reflection, Scattered E5Zxp3 N
Transmission (BTDF). Scattered Reflection (BRDF), and Absorption. _)a! g-Do7
N?l
For your property, I expect that Specular Transmission, Specular Reflection, EXizRL-9o
and Absorption would all be 0, leaving only Scattered Transmission (BTDF). *T-v^ndJh
Scattered Reflection (BRDF). BTDF and BRDF are controlled by 3 coefficients - PM8*/4Cu.5
A, B, and g. For an initial estimate, I would suggest entering BTDF(g) = |0$7{nQ
BRDF(g) = 0, which defines a Lambertian dsitribution. 9 D{p^hd
5-! Zm]
The challenge is to determine the proper ratio of Transmittance vs d 6=Z=4w
Reflectance. You can enter a value for BRDF(A) and then use the Solve For n _eN|m?@
feature to solve for BTDF, and the editor will display the resulting [W Ud9fUL
Integrated BTDF and Integrated BRDF values. You want these to sum to 1, and Q60 '5Wt
to have a ratio that matches the behavior of your surface. If the ratio of T 'tJ@+(tqw
vs R is dependent on the Incidence Angle, you can use the Add button in the m~R Me9Qi
property to add Incidence ANgles to the table, and then define the BTDF and K-Fro~U
BRDF separately for each incidence angle.
