Solution: )o=ip m[
The plastic material with the rough diffusing surface can be modeled in [|5gw3 y
TracePro, but as two separate properties (select Define/EditPropertyData). ?o>JX.Nl&7
nq/SGo[c
MATERIAL PROPERTY | H .
A TracePro Material Property can be created, and the index of refraction of Y&![2o.Q
the material is entered here, as well as an absorption coefficient if it is 9"g!J|+
known (this would be for absorption losses just from propogating through a C>ME gGP
given thickness of a clear polished sample of the material, unrelated to the dcn/|"jr
diffusing surface finish. Entering zero for the absorption coefficient is f4mQDRlD
propobly a reasonable estimate for a transparent material. 7o99@K,
8@)4)+e
The Material Property is applied to the Object (Define/Apply Properties). 6T`F'Fk[
?q*,,+'0
SURFACE PROPERTY p;x3gc;0
A TracePro Surface Property can specify 5 possible outcomes for light incident Ic<J]+Xq
on a surface - Specular Transmission, Specular Reflection, Scattered :`Z 'vRj
Transmission (BTDF). Scattered Reflection (BRDF), and Absorption. G/)]aGr
e`7dRnx&0
For your property, I expect that Specular Transmission, Specular Reflection, tCVaRP8eC+
and Absorption would all be 0, leaving only Scattered Transmission (BTDF). pXE'5IIN
Scattered Reflection (BRDF). BTDF and BRDF are controlled by 3 coefficients - ,UveH` n-
A, B, and g. For an initial estimate, I would suggest entering BTDF(g) =
BH<jnQ
BRDF(g) = 0, which defines a Lambertian dsitribution. `mt x+C
H\PY\O&cP
The challenge is to determine the proper ratio of Transmittance vs ~d9@m#_T#~
Reflectance. You can enter a value for BRDF(A) and then use the Solve For LQo>wl
feature to solve for BTDF, and the editor will display the resulting &{R]v/{p]
Integrated BTDF and Integrated BRDF values. You want these to sum to 1, and ([#4H3uO-
to have a ratio that matches the behavior of your surface. If the ratio of T g[%iVZ
vs R is dependent on the Incidence Angle, you can use the Add button in the v PJ=~*P =
property to add Incidence ANgles to the table, and then define the BTDF and y@'~fI!E4
BRDF separately for each incidence angle.
