Solution: C5 Mpm)-%
The plastic material with the rough diffusing surface can be modeled in Ml6}47n
TracePro, but as two separate properties (select Define/EditPropertyData). YmD~&J
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MATERIAL PROPERTY qtuT%?wT@Z
A TracePro Material Property can be created, and the index of refraction of ;@qQ^!g2
the material is entered here, as well as an absorption coefficient if it is ^%O $7*
known (this would be for absorption losses just from propogating through a q);oO\<
given thickness of a clear polished sample of the material, unrelated to the jT`u!CwdT
diffusing surface finish. Entering zero for the absorption coefficient is *onVG5<
propobly a reasonable estimate for a transparent material. hPuF:iiQ4
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The Material Property is applied to the Object (Define/Apply Properties). |Xmzq X%
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SURFACE PROPERTY i
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A TracePro Surface Property can specify 5 possible outcomes for light incident `>=@Kc
on a surface - Specular Transmission, Specular Reflection, Scattered r,q.RWuII
Transmission (BTDF). Scattered Reflection (BRDF), and Absorption. a:s$[+'Y
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For your property, I expect that Specular Transmission, Specular Reflection, !-t"}^)
and Absorption would all be 0, leaving only Scattered Transmission (BTDF). f8-~&N/_R
Scattered Reflection (BRDF). BTDF and BRDF are controlled by 3 coefficients - DABV}@ K"
A, B, and g. For an initial estimate, I would suggest entering BTDF(g) = n[\L6}
BRDF(g) = 0, which defines a Lambertian dsitribution. P MI?PC[;
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The challenge is to determine the proper ratio of Transmittance vs #Q BW%L
Reflectance. You can enter a value for BRDF(A) and then use the Solve For Q.Y6
feature to solve for BTDF, and the editor will display the resulting ,{_56j^d,
Integrated BTDF and Integrated BRDF values. You want these to sum to 1, and SNf~%B?`L
to have a ratio that matches the behavior of your surface. If the ratio of T 1Se2@WR'
vs R is dependent on the Incidence Angle, you can use the Add button in the iLN O}EUL
property to add Incidence ANgles to the table, and then define the BTDF and bI8')a
BRDF separately for each incidence angle.
