Solution: SI7r `'7A'
The plastic material with the rough diffusing surface can be modeled in KqXPxp^_Al
TracePro, but as two separate properties (select Define/EditPropertyData). O66b^*=N}x
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MATERIAL PROPERTY Y\E7nll:.
A TracePro Material Property can be created, and the index of refraction of =an 0PN
the material is entered here, as well as an absorption coefficient if it is Xkf|^-n
known (this would be for absorption losses just from propogating through a i_p-|I:hQ
given thickness of a clear polished sample of the material, unrelated to the %4Yq
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diffusing surface finish. Entering zero for the absorption coefficient is ^N O4T
propobly a reasonable estimate for a transparent material. iO} KERfU
(.kz J\x
The Material Property is applied to the Object (Define/Apply Properties). eU\_m5xl"
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SURFACE PROPERTY o RK:{?Y
A TracePro Surface Property can specify 5 possible outcomes for light incident Lg|]|,%e
on a surface - Specular Transmission, Specular Reflection, Scattered y_2B@cj
Transmission (BTDF). Scattered Reflection (BRDF), and Absorption. l_P90zm39!
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For your property, I expect that Specular Transmission, Specular Reflection, {X-a6OQj
and Absorption would all be 0, leaving only Scattered Transmission (BTDF). [NbW"Y7
Scattered Reflection (BRDF). BTDF and BRDF are controlled by 3 coefficients - 0*6Q 8`I
A, B, and g. For an initial estimate, I would suggest entering BTDF(g) = fRp(&%8E
BRDF(g) = 0, which defines a Lambertian dsitribution. 1? ,C d
=|H.r9-PK6
The challenge is to determine the proper ratio of Transmittance vs dAi.^! !
Reflectance. You can enter a value for BRDF(A) and then use the Solve For FDuIm,NI
feature to solve for BTDF, and the editor will display the resulting "lL/OmG
Integrated BTDF and Integrated BRDF values. You want these to sum to 1, and _ U Y5
to have a ratio that matches the behavior of your surface. If the ratio of T 4j<[3~:0
o
vs R is dependent on the Incidence Angle, you can use the Add button in the }+K=>.
property to add Incidence ANgles to the table, and then define the BTDF and ?3<Y/Vg%c
BRDF separately for each incidence angle.
