Solution: Ha )ANAD
The plastic material with the rough diffusing surface can be modeled in K #.
TracePro, but as two separate properties (select Define/EditPropertyData). o=1X^,
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MATERIAL PROPERTY ^Ox3XC
A TracePro Material Property can be created, and the index of refraction of qg rg CJ
the material is entered here, as well as an absorption coefficient if it is W 5R\Q,x6
known (this would be for absorption losses just from propogating through a =JmT:enV
given thickness of a clear polished sample of the material, unrelated to the f7}*X|_Y
diffusing surface finish. Entering zero for the absorption coefficient is 3 h< ,
propobly a reasonable estimate for a transparent material. {AQ=<RDRF
--DoB=5%8
The Material Property is applied to the Object (Define/Apply Properties). ^b
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SURFACE PROPERTY P~ &$l2
A TracePro Surface Property can specify 5 possible outcomes for light incident Ps<d('=
on a surface - Specular Transmission, Specular Reflection, Scattered n93=8;&
Transmission (BTDF). Scattered Reflection (BRDF), and Absorption. M +x,opl
mml
z& h
For your property, I expect that Specular Transmission, Specular Reflection, ~ar=P mYV7
and Absorption would all be 0, leaving only Scattered Transmission (BTDF). ]~ Z6;
Scattered Reflection (BRDF). BTDF and BRDF are controlled by 3 coefficients - Qa.u Mq
A, B, and g. For an initial estimate, I would suggest entering BTDF(g) = zen*PeIrA^
BRDF(g) = 0, which defines a Lambertian dsitribution. =)7s $
p
@$z<i `4
The challenge is to determine the proper ratio of Transmittance vs twx[ s$O'b
Reflectance. You can enter a value for BRDF(A) and then use the Solve For 0P]E 6hWgg
feature to solve for BTDF, and the editor will display the resulting PsZ
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Integrated BTDF and Integrated BRDF values. You want these to sum to 1, and 3 g6j?yYqb
to have a ratio that matches the behavior of your surface. If the ratio of T y8DhOlewQ
vs R is dependent on the Incidence Angle, you can use the Add button in the jQ)T6 7
property to add Incidence ANgles to the table, and then define the BTDF and +}a ]GTBgA
BRDF separately for each incidence angle.
