Solution: kVe4 #LT
The plastic material with the rough diffusing surface can be modeled in ;lP/hG;`
TracePro, but as two separate properties (select Define/EditPropertyData). cKED RX3
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MATERIAL PROPERTY a${<~M
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A TracePro Material Property can be created, and the index of refraction of slTE.
the material is entered here, as well as an absorption coefficient if it is e%_J
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known (this would be for absorption losses just from propogating through a C116 c "
given thickness of a clear polished sample of the material, unrelated to the riv8qg
diffusing surface finish. Entering zero for the absorption coefficient is d+o.J",E
propobly a reasonable estimate for a transparent material. 38E
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The Material Property is applied to the Object (Define/Apply Properties). J ~.`
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SURFACE PROPERTY s3sPj2e{
A TracePro Surface Property can specify 5 possible outcomes for light incident E< Y!BT[X
on a surface - Specular Transmission, Specular Reflection, Scattered `F`{s`E)
Transmission (BTDF). Scattered Reflection (BRDF), and Absorption. W+Q^u7K
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For your property, I expect that Specular Transmission, Specular Reflection, Y?v{V>;*A
and Absorption would all be 0, leaving only Scattered Transmission (BTDF). of=N+
W
Scattered Reflection (BRDF). BTDF and BRDF are controlled by 3 coefficients - pv]2"|]V)
A, B, and g. For an initial estimate, I would suggest entering BTDF(g) = `nrw[M?
BRDF(g) = 0, which defines a Lambertian dsitribution. (L<q Jd1Q
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The challenge is to determine the proper ratio of Transmittance vs aY-7K._</
Reflectance. You can enter a value for BRDF(A) and then use the Solve For [9^lAhX
feature to solve for BTDF, and the editor will display the resulting ["^? vhv
Integrated BTDF and Integrated BRDF values. You want these to sum to 1, and 1I?`3N
to have a ratio that matches the behavior of your surface. If the ratio of T 8+@j %l j
vs R is dependent on the Incidence Angle, you can use the Add button in the }0V aZ<j
property to add Incidence ANgles to the table, and then define the BTDF and 9 2x)Pc^D
BRDF separately for each incidence angle.
