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The plastic material with the rough diffusing surface can be modeled in J `q]6qf#
TracePro, but as two separate properties (select Define/EditPropertyData). $&s=68
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MATERIAL PROPERTY "Td`AuP@,
A TracePro Material Property can be created, and the index of refraction of c^ r OImZ
the material is entered here, as well as an absorption coefficient if it is C 3 hv*
known (this would be for absorption losses just from propogating through a V}d 9f 2
given thickness of a clear polished sample of the material, unrelated to the 5(W" - A}
diffusing surface finish. Entering zero for the absorption coefficient is Nw& !}#m
propobly a reasonable estimate for a transparent material. Mypc3
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The Material Property is applied to the Object (Define/Apply Properties).
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SURFACE PROPERTY Qu=LnGo~P
A TracePro Surface Property can specify 5 possible outcomes for light incident G$'jEa<:u
on a surface - Specular Transmission, Specular Reflection, Scattered SvN9aD1
Transmission (BTDF). Scattered Reflection (BRDF), and Absorption. q#Zs \PD
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For your property, I expect that Specular Transmission, Specular Reflection, w {~+EolK
and Absorption would all be 0, leaving only Scattered Transmission (BTDF). lf>*Y.!@me
Scattered Reflection (BRDF). BTDF and BRDF are controlled by 3 coefficients - GU't%[
A, B, and g. For an initial estimate, I would suggest entering BTDF(g) = ] sz3 ]"2
BRDF(g) = 0, which defines a Lambertian dsitribution. <PPNhf8
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The challenge is to determine the proper ratio of Transmittance vs Uie? 9&3
Reflectance. You can enter a value for BRDF(A) and then use the Solve For %N;!+
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feature to solve for BTDF, and the editor will display the resulting *`j-i
Integrated BTDF and Integrated BRDF values. You want these to sum to 1, and "G-1>:
to have a ratio that matches the behavior of your surface. If the ratio of T 'Y$R~e^Y?
vs R is dependent on the Incidence Angle, you can use the Add button in the 9_\ 'LJ
property to add Incidence ANgles to the table, and then define the BTDF and _, ;j7%j
BRDF separately for each incidence angle.
