Solution: ''+6qH-.|]
The plastic material with the rough diffusing surface can be modeled in 1&S34wJF
TracePro, but as two separate properties (select Define/EditPropertyData). #/u% sX`#y
g`6 _Ao8
MATERIAL PROPERTY 3l?D%E]P
A TracePro Material Property can be created, and the index of refraction of }}AooziH9
the material is entered here, as well as an absorption coefficient if it is q8U*
known (this would be for absorption losses just from propogating through a =.q
Zgcg
given thickness of a clear polished sample of the material, unrelated to the F`W8\u'db
diffusing surface finish. Entering zero for the absorption coefficient is @<$-*,
propobly a reasonable estimate for a transparent material. PP \nR
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The Material Property is applied to the Object (Define/Apply Properties). 8V c g30_+
rQ0V3x1"Qx
SURFACE PROPERTY ;J"b% ~Gn
A TracePro Surface Property can specify 5 possible outcomes for light incident *82f {t]
on a surface - Specular Transmission, Specular Reflection, Scattered wB(A['k
Transmission (BTDF). Scattered Reflection (BRDF), and Absorption. k)VoDxMKK
e0i &?m
For your property, I expect that Specular Transmission, Specular Reflection, 4a'GWzUtS
and Absorption would all be 0, leaving only Scattered Transmission (BTDF). kHj|:,'sV
Scattered Reflection (BRDF). BTDF and BRDF are controlled by 3 coefficients - Z)RoFD1]C
A, B, and g. For an initial estimate, I would suggest entering BTDF(g) = $ b Q4[
BRDF(g) = 0, which defines a Lambertian dsitribution. .8[Db1W
{VWX?Mm
The challenge is to determine the proper ratio of Transmittance vs qPJU}(9#B
Reflectance. You can enter a value for BRDF(A) and then use the Solve For P<AN`un
feature to solve for BTDF, and the editor will display the resulting {-2 8%
Integrated BTDF and Integrated BRDF values. You want these to sum to 1, and 1BQB8i-,
to have a ratio that matches the behavior of your surface. If the ratio of T J|k~e,C
vs R is dependent on the Incidence Angle, you can use the Add button in the *], ]E;
property to add Incidence ANgles to the table, and then define the BTDF and Dps0$f c
BRDF separately for each incidence angle.
