Hi Radiance experts,
I was simulating on a translucent material based on Radiance BRTDfunc material primitive. And the model I used was from CIE test case (CIE 171:2006), a simple 4m×4m×3m box with a roof opening of 1m×1m in the middle. But I found the results confusing because the BRTDfunc result was almost the same as that of an opening without any cover, as illustrated in the following picture. I also used a Trans material primitive to compare with BRTDfunc, and it seemed more correct.
Here’s my BRTDfunc material definition:
void BRTDfunc Sample4_front&back
0.0116 0.0139 0.0155
0 0 0
9 0.5875 0.5892 0.6238 0.5892 0.5897 0.6243 0.4291 0.3959 0.3836
And here’s my Trans material definition, using the same measured optical data as in BRTDfunc:
void trans Sample4_Trans
7 1 1 1 0 0 0.4 0.03
And the formulas I use for calculating Trans parameters are:
A7=Ts / ( Td+Ts )
A6=( Td+Ts ) / ( Rd+Td+Ts )
A3=Cb / ( (1-Rs)(1-A6) )
A2=Cg / ( (1-Rs)(1-A6) )
A1=Cr / ( (1-Rs)*(1-A6) )
And now I don’t know what the problem is. Maybe it’s the way I using BRTDfunc that goes wrong.
Can you kindly help me out with this issue and give some advice? Thank you in advance!