Solution: BM W4E 5
The plastic material with the rough diffusing surface can be modeled in q.t5L=l^
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TracePro, but as two separate properties (select Define/EditPropertyData). ~}11 6K
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MATERIAL PROPERTY h^)2:0#{I
A TracePro Material Property can be created, and the index of refraction of o_5@R+&
the material is entered here, as well as an absorption coefficient if it is U|QDV16f
known (this would be for absorption losses just from propogating through a -d~'tti
given thickness of a clear polished sample of the material, unrelated to the WveFB%@`;
diffusing surface finish. Entering zero for the absorption coefficient is "8I4]'
propobly a reasonable estimate for a transparent material. !]nCeo
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The Material Property is applied to the Object (Define/Apply Properties). ZjK~s)RC
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SURFACE PROPERTY m~ K]|]iqQ
A TracePro Surface Property can specify 5 possible outcomes for light incident hd B[H8Q
on a surface - Specular Transmission, Specular Reflection, Scattered F*=RP$sj
Transmission (BTDF). Scattered Reflection (BRDF), and Absorption. 8 FITcK^
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For your property, I expect that Specular Transmission, Specular Reflection, '9gI=/29D
and Absorption would all be 0, leaving only Scattered Transmission (BTDF). ao!r6:&v$e
Scattered Reflection (BRDF). BTDF and BRDF are controlled by 3 coefficients - @!da1jN
A, B, and g. For an initial estimate, I would suggest entering BTDF(g) = *GhRU5
BRDF(g) = 0, which defines a Lambertian dsitribution. [8w2U%}]
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The challenge is to determine the proper ratio of Transmittance vs #u$z-M !
Reflectance. You can enter a value for BRDF(A) and then use the Solve For Ah`dt 8t
feature to solve for BTDF, and the editor will display the resulting ccSS a u5N
Integrated BTDF and Integrated BRDF values. You want these to sum to 1, and DvCt^ O*
to have a ratio that matches the behavior of your surface. If the ratio of T ^xwFjQXx
vs R is dependent on the Incidence Angle, you can use the Add button in the LayU)TIt
property to add Incidence ANgles to the table, and then define the BTDF and M=A9a x
BRDF separately for each incidence angle.
