Solution: w5C$39e\G
The plastic material with the rough diffusing surface can be modeled in #[
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TracePro, but as two separate properties (select Define/EditPropertyData). R m&^[mv
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MATERIAL PROPERTY Q)/V >QW
A TracePro Material Property can be created, and the index of refraction of <Ny DrO"C3
the material is entered here, as well as an absorption coefficient if it is Wz8 MV -D
known (this would be for absorption losses just from propogating through a B4D#T lB
given thickness of a clear polished sample of the material, unrelated to the 8 vp*U
diffusing surface finish. Entering zero for the absorption coefficient is KT 4h3D`,
propobly a reasonable estimate for a transparent material. Bf21u 9
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The Material Property is applied to the Object (Define/Apply Properties). y[D8r Fw
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SURFACE PROPERTY b p[wr
A TracePro Surface Property can specify 5 possible outcomes for light incident 1*aO2dOq
on a surface - Specular Transmission, Specular Reflection, Scattered a-cLy*W,~
Transmission (BTDF). Scattered Reflection (BRDF), and Absorption. Daw;6f:
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For your property, I expect that Specular Transmission, Specular Reflection, Qm"&=<
and Absorption would all be 0, leaving only Scattered Transmission (BTDF). $_ BoG
Scattered Reflection (BRDF). BTDF and BRDF are controlled by 3 coefficients - xg;o<y KF
A, B, and g. For an initial estimate, I would suggest entering BTDF(g) = PM?F;mj
BRDF(g) = 0, which defines a Lambertian dsitribution. h 7P<3m}
wHR# - g'
The challenge is to determine the proper ratio of Transmittance vs r6b;v2!8
Reflectance. You can enter a value for BRDF(A) and then use the Solve For Uh w:XV@m
feature to solve for BTDF, and the editor will display the resulting ^t $xR_
Integrated BTDF and Integrated BRDF values. You want these to sum to 1, and j; MQ_?"iN
to have a ratio that matches the behavior of your surface. If the ratio of T ~pC\"LU`
vs R is dependent on the Incidence Angle, you can use the Add button in the sTS Nu+
property to add Incidence ANgles to the table, and then define the BTDF and 1_jd1 UT
BRDF separately for each incidence angle.
