Solution: 2 Do^N5y
The plastic material with the rough diffusing surface can be modeled in =sPY+ ~<o
TracePro, but as two separate properties (select Define/EditPropertyData). %=S~[&8C
k6QQoLb$V
MATERIAL PROPERTY Txj%o5G
A TracePro Material Property can be created, and the index of refraction of 959&I0=g"
the material is entered here, as well as an absorption coefficient if it is 0:@:cz=#*
known (this would be for absorption losses just from propogating through a _h MMm6a|
given thickness of a clear polished sample of the material, unrelated to the > mgbs>
diffusing surface finish. Entering zero for the absorption coefficient is lnEc5J@c>i
propobly a reasonable estimate for a transparent material. 8h78Zb&[
W 0K&mBu
The Material Property is applied to the Object (Define/Apply Properties). "/[-U;ck
a 9(1 6k
SURFACE PROPERTY 8tK 8|t5+
A TracePro Surface Property can specify 5 possible outcomes for light incident , pq<.?&E
on a surface - Specular Transmission, Specular Reflection, Scattered nG1 m x/w
Transmission (BTDF). Scattered Reflection (BRDF), and Absorption. #^" \WG7{
l=`)yc.
For your property, I expect that Specular Transmission, Specular Reflection, g(7htWr4
and Absorption would all be 0, leaving only Scattered Transmission (BTDF). pj6 Q0h)
Scattered Reflection (BRDF). BTDF and BRDF are controlled by 3 coefficients - Ultx|qU
A, B, and g. For an initial estimate, I would suggest entering BTDF(g) =
dur}3oS0p
BRDF(g) = 0, which defines a Lambertian dsitribution. Y
[0 S
C=t:0.:PJ
The challenge is to determine the proper ratio of Transmittance vs u 3wF)B{
Reflectance. You can enter a value for BRDF(A) and then use the Solve For /x"gpKwsB
feature to solve for BTDF, and the editor will display the resulting qN1(mxa.?
Integrated BTDF and Integrated BRDF values. You want these to sum to 1, and gz;( ).{
to have a ratio that matches the behavior of your surface. If the ratio of T :=UiE DN@
vs R is dependent on the Incidence Angle, you can use the Add button in the 1c(1 YGuH
property to add Incidence ANgles to the table, and then define the BTDF and 4r\Sbh
BRDF separately for each incidence angle.
