Solution: 2rP!]
The plastic material with the rough diffusing surface can be modeled in bb/A}<
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TracePro, but as two separate properties (select Define/EditPropertyData). ,`ehR6b
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MATERIAL PROPERTY #{bT=:3a
A TracePro Material Property can be created, and the index of refraction of x*^)B~7}
the material is entered here, as well as an absorption coefficient if it is a! x?Apww
known (this would be for absorption losses just from propogating through a 7&|&y
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given thickness of a clear polished sample of the material, unrelated to the tN;~.\TKg
diffusing surface finish. Entering zero for the absorption coefficient is ;x{J45^
propobly a reasonable estimate for a transparent material. 8+_e= _3R
kf", /?s2Z
The Material Property is applied to the Object (Define/Apply Properties). [py/\zkn
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SURFACE PROPERTY 8`w#)6(V
A TracePro Surface Property can specify 5 possible outcomes for light incident F,GG>(6c
on a surface - Specular Transmission, Specular Reflection, Scattered -Ze2]^#dl
Transmission (BTDF). Scattered Reflection (BRDF), and Absorption. PsS8b
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For your property, I expect that Specular Transmission, Specular Reflection, @2A&eLw LH
and Absorption would all be 0, leaving only Scattered Transmission (BTDF). N*hx;k9
Scattered Reflection (BRDF). BTDF and BRDF are controlled by 3 coefficients - V elX+|w
A, B, and g. For an initial estimate, I would suggest entering BTDF(g) = /$ueLa
BRDF(g) = 0, which defines a Lambertian dsitribution. }cy<$=c#E_
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The challenge is to determine the proper ratio of Transmittance vs hKK"D:?PRs
Reflectance. You can enter a value for BRDF(A) and then use the Solve For 2I ~a{:O
feature to solve for BTDF, and the editor will display the resulting iJ`v 3PP
Integrated BTDF and Integrated BRDF values. You want these to sum to 1, and =G/`r!r*0I
to have a ratio that matches the behavior of your surface. If the ratio of T /u'M7R
vs R is dependent on the Incidence Angle, you can use the Add button in the ~c
GH+M@
property to add Incidence ANgles to the table, and then define the BTDF and *3Ci4\Ew
BRDF separately for each incidence angle.
