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The plastic material with the rough diffusing surface can be modeled in XNODDH
TracePro, but as two separate properties (select Define/EditPropertyData). z^;0 { q,
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MATERIAL PROPERTY _J' _9M?>
A TracePro Material Property can be created, and the index of refraction of `1;m:,9
the material is entered here, as well as an absorption coefficient if it is AP1Eiv<Hub
known (this would be for absorption losses just from propogating through a |ipL.<v7
given thickness of a clear polished sample of the material, unrelated to the 4KH8dau.fF
diffusing surface finish. Entering zero for the absorption coefficient is <UI^~Azc#
propobly a reasonable estimate for a transparent material. -nM=^ i4)
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The Material Property is applied to the Object (Define/Apply Properties). XEK% \o}
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SURFACE PROPERTY `[.b>ztqgJ
A TracePro Surface Property can specify 5 possible outcomes for light incident v[-.]b*5A$
on a surface - Specular Transmission, Specular Reflection, Scattered fjD/<` }v
Transmission (BTDF). Scattered Reflection (BRDF), and Absorption. mar6/*`I#+
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For your property, I expect that Specular Transmission, Specular Reflection, # !:u*1
and Absorption would all be 0, leaving only Scattered Transmission (BTDF). {,
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Scattered Reflection (BRDF). BTDF and BRDF are controlled by 3 coefficients - q 6R``
A, B, and g. For an initial estimate, I would suggest entering BTDF(g) = ,0j7qn@tm
BRDF(g) = 0, which defines a Lambertian dsitribution. [WZGu6$SU
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The challenge is to determine the proper ratio of Transmittance vs X*4iNyIs_
Reflectance. You can enter a value for BRDF(A) and then use the Solve For /=o~7y
feature to solve for BTDF, and the editor will display the resulting G3[X.%g`
Integrated BTDF and Integrated BRDF values. You want these to sum to 1, and H > Y0R
to have a ratio that matches the behavior of your surface. If the ratio of T .
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vs R is dependent on the Incidence Angle, you can use the Add button in the . }#R
property to add Incidence ANgles to the table, and then define the BTDF and ^?-SMcUHB
BRDF separately for each incidence angle.
