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The plastic material with the rough diffusing surface can be modeled in `II/nv0jn
TracePro, but as two separate properties (select Define/EditPropertyData). ekj@;6
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MATERIAL PROPERTY aN5 w
A TracePro Material Property can be created, and the index of refraction of 5-ju5z?=
the material is entered here, as well as an absorption coefficient if it is $`&u u
known (this would be for absorption losses just from propogating through a C4jq T
given thickness of a clear polished sample of the material, unrelated to the YQI&8~z
diffusing surface finish. Entering zero for the absorption coefficient is ,^UNQO*{GI
propobly a reasonable estimate for a transparent material. +EWfsKz
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The Material Property is applied to the Object (Define/Apply Properties). Ws ;}D}+
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SURFACE PROPERTY }I\hO L
A TracePro Surface Property can specify 5 possible outcomes for light incident 5`B ! 1
on a surface - Specular Transmission, Specular Reflection, Scattered p/a)vN+*x'
Transmission (BTDF). Scattered Reflection (BRDF), and Absorption. :/kz*X=<
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For your property, I expect that Specular Transmission, Specular Reflection, :u7y k@
and Absorption would all be 0, leaving only Scattered Transmission (BTDF). ~fE6g3
Scattered Reflection (BRDF). BTDF and BRDF are controlled by 3 coefficients - tC=`J%Ik
A, B, and g. For an initial estimate, I would suggest entering BTDF(g) = 9cu0$P`}5
BRDF(g) = 0, which defines a Lambertian dsitribution. }!-K )j .
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The challenge is to determine the proper ratio of Transmittance vs + W ?
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Reflectance. You can enter a value for BRDF(A) and then use the Solve For av&4:O!
feature to solve for BTDF, and the editor will display the resulting Cku&s
Integrated BTDF and Integrated BRDF values. You want these to sum to 1, and hYS*J908
to have a ratio that matches the behavior of your surface. If the ratio of T I3A@0'Vm;L
vs R is dependent on the Incidence Angle, you can use the Add button in the ^uu)|
property to add Incidence ANgles to the table, and then define the BTDF and Z[DiLXHL
BRDF separately for each incidence angle.
