[Radiance-general] Trans material - tspec value

[Shrikar Bhave]

Hello All,

I am trying to compare diffusion properties of a glazing assembly by
rendering an exact same scene but changing only the 'tspec' value from 0
(ideal diffuser) to 0.9 (almost clear). I have a room with clerestory
windows which consist of 2 layers of translucent panels. Exterior glazing
is 60% VLT and interior glazing is 30% VLT with about a 30cm of cavity in
between.

*Simulation 1*
void trans panelext60
0 0 7 0.978494624 0.978494624 0.978494624 0.07 0 0.65934066 0

void trans panelint30
0 0 7 0.978494624 0.978494624 0.978494624 0.07 0 0.32967033 0


*Simulation 2*
void trans panelext60
0 0 7 0.978494624 0.978494624 0.978494624 0.07 0 0.65934066 0.9

void trans panelint30
0 0 7 0.978494624 0.978494624 0.978494624 0.07 0 0.32967033 0.9

rpict command is as follows,

rpict -vtv -vp 0.1 7.3 1.8 -vd 1 0 0 -vu 0 0 1 -vh 130 -vv 90 -x 3000 -y
1400 -ab 4 -aa 0.08 -ar 512 -ad 2048 -as 512 -ds .01 -dj .6 -t 60 sunny.oct
> lookeast_june21_noon.pic

I was expecting a significant difference in renderings for 2 scenes. The
second simulation should have resulted in more defined bright patches.
Though that's not the case. Am I missing something obvious here?
Unfortunately I cannot attach the complete renderings due to confidential
nature of the project. I have attached screenshots of the area of interest.

Any help is much appreciated,

Thanks,

Shri
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