Solution: #dft-23
The plastic material with the rough diffusing surface can be modeled in W24bO|>D
TracePro, but as two separate properties (select Define/EditPropertyData). "v1(f| a
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MATERIAL PROPERTY s]iOC6v
A TracePro Material Property can be created, and the index of refraction of &J b.OCf
the material is entered here, as well as an absorption coefficient if it is 0Nu]N)H5<l
known (this would be for absorption losses just from propogating through a b wJi[xF
given thickness of a clear polished sample of the material, unrelated to the vt
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diffusing surface finish. Entering zero for the absorption coefficient is 76b7- Nj"
propobly a reasonable estimate for a transparent material. c)8wO=!
{yHfE,
The Material Property is applied to the Object (Define/Apply Properties). k)p y\
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SURFACE PROPERTY uKy *N* }
A TracePro Surface Property can specify 5 possible outcomes for light incident %SGO"*_
on a surface - Specular Transmission, Specular Reflection, Scattered <.b$
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Transmission (BTDF). Scattered Reflection (BRDF), and Absorption. ^wa9zs2s;/
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For your property, I expect that Specular Transmission, Specular Reflection, Lf#G?]@
and Absorption would all be 0, leaving only Scattered Transmission (BTDF). Y14R"*t~
Scattered Reflection (BRDF). BTDF and BRDF are controlled by 3 coefficients - 1Q SIZoK7
A, B, and g. For an initial estimate, I would suggest entering BTDF(g) = mM* yv
BRDF(g) = 0, which defines a Lambertian dsitribution. "yTh + =
-ZP&zOsDr
The challenge is to determine the proper ratio of Transmittance vs wsrx|n[]
Reflectance. You can enter a value for BRDF(A) and then use the Solve For
:XSc#H4
feature to solve for BTDF, and the editor will display the resulting ^P/D8cXa4
Integrated BTDF and Integrated BRDF values. You want these to sum to 1, and e: LZ s0
to have a ratio that matches the behavior of your surface. If the ratio of T Iv72;ZCh?6
vs R is dependent on the Incidence Angle, you can use the Add button in the J&:W4\ m
property to add Incidence ANgles to the table, and then define the BTDF and l;*l PRoW,
BRDF separately for each incidence angle.
