Solution: 2
The plastic material with the rough diffusing surface can be modeled in [ p~,;%
TracePro, but as two separate properties (select Define/EditPropertyData). s;=C&N5g
V=% ;5/
MATERIAL PROPERTY al-r gh
A TracePro Material Property can be created, and the index of refraction of ^jUw4Dj~-q
the material is entered here, as well as an absorption coefficient if it is GN9kCyPK
known (this would be for absorption losses just from propogating through a XZ M@Rys
given thickness of a clear polished sample of the material, unrelated to the J=gFiBw
diffusing surface finish. Entering zero for the absorption coefficient is xy4+
[u
propobly a reasonable estimate for a transparent material. ;^0 rY )&
; :q
The Material Property is applied to the Object (Define/Apply Properties). @2a!T03
5E"^>z
SURFACE PROPERTY Ie(.T2K
A TracePro Surface Property can specify 5 possible outcomes for light incident r
1jt~0&K
on a surface - Specular Transmission, Specular Reflection, Scattered c-} [v<o
Transmission (BTDF). Scattered Reflection (BRDF), and Absorption. W]7 /
e
lw[ c+F7
For your property, I expect that Specular Transmission, Specular Reflection, <F(2D<d{;)
and Absorption would all be 0, leaving only Scattered Transmission (BTDF). ,Kl?-W@
Scattered Reflection (BRDF). BTDF and BRDF are controlled by 3 coefficients - p r7lm5
A, B, and g. For an initial estimate, I would suggest entering BTDF(g) = 3Jlap=]68S
BRDF(g) = 0, which defines a Lambertian dsitribution. Rz|@Bx B>n
0V21_" .S
The challenge is to determine the proper ratio of Transmittance vs x: _[R{B
Reflectance. You can enter a value for BRDF(A) and then use the Solve For &KAe+~aPm
feature to solve for BTDF, and the editor will display the resulting 6 h,!;`8O
Integrated BTDF and Integrated BRDF values. You want these to sum to 1, and {G LGDEb
to have a ratio that matches the behavior of your surface. If the ratio of T dpsc gW{M
vs R is dependent on the Incidence Angle, you can use the Add button in the -f mJkI
property to add Incidence ANgles to the table, and then define the BTDF and i,a" 5D R8
BRDF separately for each incidence angle.
