Solution: ^w}BXVn
The plastic material with the rough diffusing surface can be modeled in ]:]w+N%7
TracePro, but as two separate properties (select Define/EditPropertyData). tj!~7lo
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MATERIAL PROPERTY {D 8[pG%z
A TracePro Material Property can be created, and the index of refraction of !='& #@7u
the material is entered here, as well as an absorption coefficient if it is ->YF</I
known (this would be for absorption losses just from propogating through a !RdubM
given thickness of a clear polished sample of the material, unrelated to the L)Ru]X`
diffusing surface finish. Entering zero for the absorption coefficient is K06&.>v_
propobly a reasonable estimate for a transparent material. bU"2D.k
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The Material Property is applied to the Object (Define/Apply Properties). Xb AoW\D(
D~<0CQ3n.
SURFACE PROPERTY _Nq7_iT0
A TracePro Surface Property can specify 5 possible outcomes for light incident <Okl.Iz>
on a surface - Specular Transmission, Specular Reflection, Scattered Wp$'#H hB
Transmission (BTDF). Scattered Reflection (BRDF), and Absorption. *[['X%f
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For your property, I expect that Specular Transmission, Specular Reflection, [mI;>q
and Absorption would all be 0, leaving only Scattered Transmission (BTDF). {f)"F;]V
Scattered Reflection (BRDF). BTDF and BRDF are controlled by 3 coefficients - S A16Ng
A, B, and g. For an initial estimate, I would suggest entering BTDF(g) = w!^{Q'/, Q
BRDF(g) = 0, which defines a Lambertian dsitribution. Uu3< S
1{X ;&y
The challenge is to determine the proper ratio of Transmittance vs gkDlh{
Reflectance. You can enter a value for BRDF(A) and then use the Solve For H#j Z'I
feature to solve for BTDF, and the editor will display the resulting &ffd#2f `@
Integrated BTDF and Integrated BRDF values. You want these to sum to 1, and !
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to have a ratio that matches the behavior of your surface. If the ratio of T dD8f`*"*=
vs R is dependent on the Incidence Angle, you can use the Add button in the }xM >F%
property to add Incidence ANgles to the table, and then define the BTDF and Va m4/6
BRDF separately for each incidence angle.
