Solution: }Lx?RU+@=
The plastic material with the rough diffusing surface can be modeled in +k'5W1e
TracePro, but as two separate properties (select Define/EditPropertyData). kmM1)- v
&j,rq?eh$
MATERIAL PROPERTY *]fBd<(8
A TracePro Material Property can be created, and the index of refraction of Bl-nS{9"
the material is entered here, as well as an absorption coefficient if it is adh=Kp e!w
known (this would be for absorption losses just from propogating through a d_&R>GmR$
given thickness of a clear polished sample of the material, unrelated to the A
e&t#,)
diffusing surface finish. Entering zero for the absorption coefficient is E8WOXoP(
propobly a reasonable estimate for a transparent material. yVm~5Y&Z
rS>JzbWa
The Material Property is applied to the Object (Define/Apply Properties). \cdNyVY
)eNR4nF
SURFACE PROPERTY y88FT#hR|5
A TracePro Surface Property can specify 5 possible outcomes for light incident ^o]ZDc
on a surface - Specular Transmission, Specular Reflection, Scattered T^8 t<S@`
Transmission (BTDF). Scattered Reflection (BRDF), and Absorption. aE6 I|6W?
T=}(S4n#BX
For your property, I expect that Specular Transmission, Specular Reflection, zR/d:P?
and Absorption would all be 0, leaving only Scattered Transmission (BTDF). <jT6|2'
Scattered Reflection (BRDF). BTDF and BRDF are controlled by 3 coefficients - }\`MXh's
A, B, and g. For an initial estimate, I would suggest entering BTDF(g) = ^ad
p<?q4
BRDF(g) = 0, which defines a Lambertian dsitribution. 2H_|Attoi
uh3%}2'P
The challenge is to determine the proper ratio of Transmittance vs W6D|Rr.q
Reflectance. You can enter a value for BRDF(A) and then use the Solve For _*1/4^
feature to solve for BTDF, and the editor will display the resulting q_5k2'4K
Integrated BTDF and Integrated BRDF values. You want these to sum to 1, and R:98'`X=
to have a ratio that matches the behavior of your surface. If the ratio of T T9\wkb.
vs R is dependent on the Incidence Angle, you can use the Add button in the IpmblC4
property to add Incidence ANgles to the table, and then define the BTDF and Qj? +R F6(
BRDF separately for each incidence angle.
