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The plastic material with the rough diffusing surface can be modeled in Ttu2 skcv
TracePro, but as two separate properties (select Define/EditPropertyData). 0IwA#[m1`
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MATERIAL PROPERTY )JDs\fUE
A TracePro Material Property can be created, and the index of refraction of 6*PYFf`
the material is entered here, as well as an absorption coefficient if it is qW$<U3u}
known (this would be for absorption losses just from propogating through a }6p@lla,%]
given thickness of a clear polished sample of the material, unrelated to the F |d\k Q
diffusing surface finish. Entering zero for the absorption coefficient is i2@VB6]?
propobly a reasonable estimate for a transparent material. \s/s7 y6b+
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The Material Property is applied to the Object (Define/Apply Properties). RHaI ~jb
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SURFACE PROPERTY <Y*+|T+&d
A TracePro Surface Property can specify 5 possible outcomes for light incident (_niMQtF}
on a surface - Specular Transmission, Specular Reflection, Scattered 8| ):`u
Transmission (BTDF). Scattered Reflection (BRDF), and Absorption. k52/w)Ro,$
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For your property, I expect that Specular Transmission, Specular Reflection, .R) D3NZp
and Absorption would all be 0, leaving only Scattered Transmission (BTDF). S'|,oUWDb
Scattered Reflection (BRDF). BTDF and BRDF are controlled by 3 coefficients - nim*/LC[:
A, B, and g. For an initial estimate, I would suggest entering BTDF(g) = HFKf kAl
BRDF(g) = 0, which defines a Lambertian dsitribution. @E;=*9ek{u
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The challenge is to determine the proper ratio of Transmittance vs 4E; VM{
Reflectance. You can enter a value for BRDF(A) and then use the Solve For D N'3QQn
feature to solve for BTDF, and the editor will display the resulting
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Integrated BTDF and Integrated BRDF values. You want these to sum to 1, and ]p _L)
to have a ratio that matches the behavior of your surface. If the ratio of T %b%-Ogz;4
vs R is dependent on the Incidence Angle, you can use the Add button in the 7F zA*
property to add Incidence ANgles to the table, and then define the BTDF and n)L*
BRDF separately for each incidence angle.
