Thanks for your reply Chris, I have tried to alter my specular treshold
(-st) to 0.05, 0.01 or even 0.
However I still get that with an incidence angle higher than 45 degress no
reflectance occur, and my transmittance increases! This was not what I would
have expected. I would have expected an increase in reflectance and a
decrease in transmittance with higher incidence angle.
My question is therefore, am I using a wrong approach to test the incidence
angle-dependency on transmittance and reflectance of my "sample"?
My approach has been to vary the rotation of the sample from 'seq 10 10 80'
plus 87 around the x-axis, and do the rtrace from "above" to achieve the
reflectance and from "below" to achieve the transmittance:
xform -rx $ROT -t 0 0 0 LamellaGlowTRANS.rad > lamellaGlow.rad
oconv Materials.mat Glow.sky lamellaGlow.rad > glow.oct
echo "reflectance:"
echo '1.75 0.1 4 0 0 -1' | rtrace -h -w -dt 0.05 -st 0.01 glow.oct
echo "transmittance:"
echo '1.75 0.1 -4 0 0 1' | rtrace -h -w -dt 0.05 -st 0.01 glow.oct
The output is attached to this mail. My trans description is given below--
(you have seen it here on the list before ;o))
# a1, a2 og a3 = 1, due to the color of the glass is included in the
transmittance end reflectance given by the manufacturer
# a4 = 0.31
# a5 = 0
# a6 = trans, determined from t_s=a6*a7(1-a4), where t_s is 0.65 and a7=1
# a7 = 1
void trans lamel_trans
0 0 7 1 1 1 0.31 0 0.942028986 1
And the glow for the sky is:
skyfunc glow sky_mat
0 0 4 1 1 1 0
sky_mat source sky
0 0 4 0 0 1 180
Thanks!
Anne
Message: 5
GlowOutput.txt (1.36 KB)
···
Date: Thu, 21 May 2009 09:56:56 -0400
From: "Christopher Rush" <[email protected]>
Subject: RE: [Radiance-general] Material made of combined trans and
mirror vs.BRTDfunc
To: "Radiance general discussion"
<[email protected]>
Message-ID:
<EB124710ADB8554C930FADF760BB2BE705492464@n-yexc01.global.arup.com>
Content-Type: text/plain; charset="us-ascii"
You may need to decrease the 'specular threshhold' setting. The default
is 0.15, which crudely means that any specular reflection less than 15%
is not accounted for. Depending on how precise you want to go you could
go down to -dt .05 or less, or even to 0, but that may bog down the
calculation.
________________________________
Sent: Thursday, May 21, 2009 5:01 AM
... I have tried to test my "sample" with a glow sky where I rotate
the sample around the x axis. However when I am above a tilt of 45
degrees I get a reflectance of 0... ( My sample have the dimensions 3.5
x 3.5 in x and y and my rtrace point is placed close to the x axis
(0.2))
...
Anne