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The plastic material with the rough diffusing surface can be modeled in E 7-@&= ]v
TracePro, but as two separate properties (select Define/EditPropertyData). YBh'EL}P
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MATERIAL PROPERTY CdL< *AH
A TracePro Material Property can be created, and the index of refraction of HSq}7S&U
the material is entered here, as well as an absorption coefficient if it is gv5*!eI
known (this would be for absorption losses just from propogating through a \d::l{VB
given thickness of a clear polished sample of the material, unrelated to the }1IpON
diffusing surface finish. Entering zero for the absorption coefficient is q+,Q <2J
propobly a reasonable estimate for a transparent material. ^pHq66d%Z
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The Material Property is applied to the Object (Define/Apply Properties). ;;&}5jcV
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SURFACE PROPERTY -_$$ Te
A TracePro Surface Property can specify 5 possible outcomes for light incident cu+FM
on a surface - Specular Transmission, Specular Reflection, Scattered # W"=ry3{
Transmission (BTDF). Scattered Reflection (BRDF), and Absorption. nB .G
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For your property, I expect that Specular Transmission, Specular Reflection, R :B^
and Absorption would all be 0, leaving only Scattered Transmission (BTDF). \l~*PG2
Scattered Reflection (BRDF). BTDF and BRDF are controlled by 3 coefficients - 1^gl}^ |B
A, B, and g. For an initial estimate, I would suggest entering BTDF(g) = Bj7gQ%>H4
BRDF(g) = 0, which defines a Lambertian dsitribution. T
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=h l }.p
The challenge is to determine the proper ratio of Transmittance vs mc4i@<_ ?
Reflectance. You can enter a value for BRDF(A) and then use the Solve For Ci rZ+o
feature to solve for BTDF, and the editor will display the resulting
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Integrated BTDF and Integrated BRDF values. You want these to sum to 1, and tJN<PCG6"
to have a ratio that matches the behavior of your surface. If the ratio of T .9. 2 Be
vs R is dependent on the Incidence Angle, you can use the Add button in the y r,=. ?C-
property to add Incidence ANgles to the table, and then define the BTDF and Sfdu`MQR
BRDF separately for each incidence angle.
