Solution: R+y 9JE
The plastic material with the rough diffusing surface can be modeled in ~ '/Yp8 (
TracePro, but as two separate properties (select Define/EditPropertyData). *kE<7
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MATERIAL PROPERTY 5:sk&0:@U
A TracePro Material Property can be created, and the index of refraction of T@)|0M
the material is entered here, as well as an absorption coefficient if it is 6A9
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known (this would be for absorption losses just from propogating through a qPG>0
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given thickness of a clear polished sample of the material, unrelated to the ]d]rV
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diffusing surface finish. Entering zero for the absorption coefficient is |qFCzK9tD/
propobly a reasonable estimate for a transparent material. r?j2%M\
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The Material Property is applied to the Object (Define/Apply Properties). $]t3pAI[H0
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SURFACE PROPERTY s7> a
A TracePro Surface Property can specify 5 possible outcomes for light incident A5[iFT>
on a surface - Specular Transmission, Specular Reflection, Scattered /_l$h_{DH
Transmission (BTDF). Scattered Reflection (BRDF), and Absorption. L.tW]4 3K
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For your property, I expect that Specular Transmission, Specular Reflection, Cl>{vS N
and Absorption would all be 0, leaving only Scattered Transmission (BTDF). $4ZjN N@
Scattered Reflection (BRDF). BTDF and BRDF are controlled by 3 coefficients - #Li6RSeW
A, B, and g. For an initial estimate, I would suggest entering BTDF(g) = O-jpS?@
BRDF(g) = 0, which defines a Lambertian dsitribution. l1I\khS
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The challenge is to determine the proper ratio of Transmittance vs o;5 ns
Reflectance. You can enter a value for BRDF(A) and then use the Solve For \\UOpl
feature to solve for BTDF, and the editor will display the resulting gql^Inx<
Integrated BTDF and Integrated BRDF values. You want these to sum to 1, and h1A Z+9
to have a ratio that matches the behavior of your surface. If the ratio of T ?hh#@61
vs R is dependent on the Incidence Angle, you can use the Add button in the qb 1JE[2F
property to add Incidence ANgles to the table, and then define the BTDF and ^Ez` WP
BRDF separately for each incidence angle.
