Illuminance Values

radiance-general
1

Hello Everyone,

I am simulating a simple office space 10' X 18' with a 6' X 6' window, and the automated Venetian blinds. I am trying to compare Illuminance values for two models:
1. In the base case the slats have the same tilt angle at one point of time ("conventional control").
2. In the prototype model, the blinds are divided into three sections: Top , Middle and Bottom Blinds, each of equal dimensions ("splitcontrol"). In each section blinds can have the different slat tilt angle.

For pilot testing I tested conventional control for 0, 45 and 90 degrees and split control for 0, 45, and 90 degrees, too (i.e. I kept the same tilt angle in each section of the split blinds just for the pilot testing and the result comparison purpose).

The results that I obtained show variation in the values of Illuminance obtained for these two models (results difference ranges from 10-150%) although the results should be the same.

Conventional Blind
genblinds whitealum main 0.0125 1.82 1.88 195 90 |xform -rz 90 -t 2.71 0.05 0.8>conventional90.rad

Split Blinds

genblinds whitealum main 0.0125 1.82 0.63 66 90 |xform -rz 90 -t 2.71 0.05 2.06>66-1-90.rad

genblinds whitealum main 0.0125 1.82 0.63 65 90 |xform -rz 90 -t 2.71 0.05 1.43>66-2-90.rad

genblinds whitealum main 0.0125 1.82 0.63 65 90 |xform -rz 90 -t 2.71 0.05 0.8>66-3-90.rad

I am using the following script to obtain the results.

#!/bin/csh -f

set mon=01
set month=Illuminancesplit90
set day=01
set coord=(-a 30.00 -o 82.35 -m 84)
rm $month.out
while($day<32)
foreach hr(08 09 10 11 12 13 14 15 16 17)
echo "hr=$hr"
set skypar=($mon $day $hr +i $coord)
echo "$month/$day/$hr">>$month.out
oconv -i 66-1-2-3-90.oct '\!gensky '"$skypar" sky.rad>hr.oct
rtrace -h -I -ab 1 -ad 4096 -as 128 -av .02 .02 .02 hr.oct<mainsamples.inp|rcalc -e '$1=47.4*$1+120*$2+11.6*$3'>>$month.out
#`./newglares.csh hr.oct $month.out`
echo " ">>$month.out
rm hr.oct
end
@ day++
echo "day=$day"
end

Considering the fact that we use the same room model, same window settings and blinds, why is there such variation in the values of results obtained?

Thanx.

G V DEEPAK
Graduate Research Assistant
M.E. Rinker, Sr. School of Building Construction.
University Of Florida.

2

Hi!

1. In the base case the slats have the same tilt angle at one
point of time ("conventional control").
2. In the prototype model, the blinds are divided into three
sections: Top , Middle and Bottom Blinds, each of equal dimensions
("splitcontrol"). In each section blinds can have the different slat
tilt angle.

(...)

For pilot testing I tested conventional control for 0, 45 and 90
degrees and split control for 0, 45, and 90 degrees, too (i.e. I kept
the same tilt angle in each section of the split blinds just for the
pilot testing and the result comparison purpose).

The results that I obtained show variation in the values of
Illuminance obtained for these two models (results difference ranges
from 10-150%) although the results should be the same.

(...)

So you mean, as the blind settings are the same for both models during
your current test runs, you actually have the same model set-up with
different geometry?

genblinds whitealum main 0.0125 1.82 0.63 66 90 |xform -rz 90 -t 2.71
0.05 2.06>66-1-90.rad

Is the "whitealum" material specular or diffuse?

rtrace -h -I -ab 1 -ad 4096 -as 128 -av .02 .02 .02
hr.oct<mainsamples.inp|rcalc -e '$1=47.4*$1+120*$2+11.6*$3'>>$month.out

Are you sure that your ambient paramters are suiteable for that set-up?
As far as I understand it, you get illumination only for the light
"directly" hitting your surfaces from the sky you generated. So you have
a very non-uniform environment for your rtrace-call. Did you ever render
an image of the scene, with the same parameters, using a fisheye-view
for the same view as your rtrace measurement point is getting? Imagine
the rtrace-measurement-point being a sensor, or put yourself into its
place, what do you expect to see - and do your rendering settings
account for that? As I have not seen the result, these are only guesses
for now, but I am pretty sure that you will need higher -ab settings for
such a set-up (probably -ab 4 or higher), and using ar and aa settings
to get a uniform luminance over your rooms surfaces. I guess your
ceiling is more or less black now (except the -av-contribution, but what
is your aw than)?

Good luck!

CU Lars.

3

You know that putting your blinds at 90 degrees closes them completely, right?

-Greg

···

From: G V DEEPAK <[email protected]>
Date: February 26, 2009 8:24:39 AM PST

Hello Everyone,

I am simulating a simple office space 10' X 18' with a 6' X 6' window, and the automated Venetian blinds. I am trying to compare Illuminance values for two models:
1. In the base case the slats have the same tilt angle at one point of time ("conventional control").
2. In the prototype model, the blinds are divided into three sections: Top , Middle and Bottom Blinds, each of equal dimensions ("splitcontrol"). In each section blinds can have the different slat tilt angle.

For pilot testing I tested conventional control for 0, 45 and 90 degrees and split control for 0, 45, and 90 degrees, too (i.e. I kept the same tilt angle in each section of the split blinds just for the pilot testing and the result comparison purpose).

The results that I obtained show variation in the values of Illuminance obtained for these two models (results difference ranges from 10-150%) although the results should be the same.

Conventional Blind
genblinds whitealum main 0.0125 1.82 1.88 195 90 |xform -rz 90 -t 2.71 0.05 0.8>conventional90.rad

Split Blinds

genblinds whitealum main 0.0125 1.82 0.63 66 90 |xform -rz 90 -t 2.71 0.05 2.06>66-1-90.rad

genblinds whitealum main 0.0125 1.82 0.63 65 90 |xform -rz 90 -t 2.71 0.05 1.43>66-2-90.rad

genblinds whitealum main 0.0125 1.82 0.63 65 90 |xform -rz 90 -t 2.71 0.05 0.8>66-3-90.rad

4

Yes,

I am aware that 90 degrees closes the blinds completely.
But still some Illuminance values are obtained after closing the blinds.

···

On Thu Feb 26 11:57:37 EST 2009, Greg Ward <[email protected]> wrote:

You know that putting your blinds at 90 degrees closes them completely, right?

-Greg

From: G V DEEPAK <[email protected]>
Date: February 26, 2009 8:24:39 AM PST

Hello Everyone,

I am simulating a simple office space 10' X 18' with a 6' X 6' window, and the automated Venetian blinds. I am trying to compare Illuminance values for two models:
1. In the base case the slats have the same tilt angle at one point of time ("conventional control").
2. In the prototype model, the blinds are divided into three sections: Top , Middle and Bottom Blinds, each of equal dimensions ("splitcontrol"). In each section blinds can have the different slat tilt angle.

For pilot testing I tested conventional control for 0, 45 and 90 degrees and split control for 0, 45, and 90 degrees, too (i.e. I kept the same tilt angle in each section of the split blinds just for the pilot testing and the result comparison purpose).

The results that I obtained show variation in the values of Illuminance obtained for these two models (results difference ranges from 10-150%) although the results should be the same.

Conventional Blind
genblinds whitealum main 0.0125 1.82 1.88 195 90 |xform -rz 90 -t 2.71 0.05 0.8>conventional90.rad

Split Blinds

genblinds whitealum main 0.0125 1.82 0.63 66 90 |xform -rz 90 -t 2.71 0.05 2.06>66-1-90.rad

genblinds whitealum main 0.0125 1.82 0.63 65 90 |xform -rz 90 -t 2.71 0.05 1.43>66-2-90.rad

genblinds whitealum main 0.0125 1.82 0.63 65 90 |xform -rz 90 -t 2.71 0.05 0.8>66-3-90.rad

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G V DEEPAK
Graduate Research Assistant
M.E. Rinker, Sr. School of Building Construction.
University Of Florida.

5

So, where is this light coming from? Are your blinds translucent? Do you have light leaks? Are there other sources of illumination? Or is it all coming from the ambient value (-av)?

-Greg

···

From: G V DEEPAK <[email protected]>
Date: February 27, 2009 8:58:45 AM PST

Yes,

I am aware that 90 degrees closes the blinds completely.
But still some Illuminance values are obtained after closing the blinds.