Solution: 48tcgFg[
The plastic material with the rough diffusing surface can be modeled in L#` 2.nU
TracePro, but as two separate properties (select Define/EditPropertyData). /"""z=q
=oE_.ux\
MATERIAL PROPERTY +`;+RDKY*
A TracePro Material Property can be created, and the index of refraction of |XKOXa3.
the material is entered here, as well as an absorption coefficient if it is :7p9t.R<$h
known (this would be for absorption losses just from propogating through a x3 7/cu
given thickness of a clear polished sample of the material, unrelated to the 7hB#x]oQo
diffusing surface finish. Entering zero for the absorption coefficient is j)jCu ;`
propobly a reasonable estimate for a transparent material. ud0QZ X
J>`v.8y
The Material Property is applied to the Object (Define/Apply Properties). F:M> z=
-$+,]t^GV
SURFACE PROPERTY >=if8t!
A TracePro Surface Property can specify 5 possible outcomes for light incident )@}A
r
on a surface - Specular Transmission, Specular Reflection, Scattered U/ ?F:QD4
Transmission (BTDF). Scattered Reflection (BRDF), and Absorption. 7:n?PN(p6a
In
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For your property, I expect that Specular Transmission, Specular Reflection, ,*/Pg 52?
and Absorption would all be 0, leaving only Scattered Transmission (BTDF). sYGR-:K
Scattered Reflection (BRDF). BTDF and BRDF are controlled by 3 coefficients - t]s94 R q
A, B, and g. For an initial estimate, I would suggest entering BTDF(g) = w#*/ y?" D
BRDF(g) = 0, which defines a Lambertian dsitribution. M_k`%o
,-@xq.D
The challenge is to determine the proper ratio of Transmittance vs fO K|:
Reflectance. You can enter a value for BRDF(A) and then use the Solve For 60"5?=D
feature to solve for BTDF, and the editor will display the resulting glv ;C/l
Integrated BTDF and Integrated BRDF values. You want these to sum to 1, and 9Ei5z6Vk/+
to have a ratio that matches the behavior of your surface. If the ratio of T L e*`r2
vs R is dependent on the Incidence Angle, you can use the Add button in the gs?8Wzh90*
property to add Incidence ANgles to the table, and then define the BTDF and /@VsqD
BRDF separately for each incidence angle.
