Sun angles,

Hello Everyone,

I am trying to find illuminance values on an yearly basis, I am expecting to get different values for different seasons. Say if we compare between march nad december, we should get higher values of illuminance for december as compared to march. But I am getting almost same values for both the months.

I am not sure if the software is considering sun angles in calculations.

I am running this script to find the values,

#!/bin/csh -f

set mon=12
set month=March
set day=21
set coord=(-a 30.00 -o 82.35 -m 84)
rm $month.out
while($day<23)
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">>$month.out
oconv room.rad '\!gensky '"$skypar" sky.rad>hr.oct
mkillum -ab 0 -ad 1024 -av 0.1 0.1 0.1 hr.oct "<" windowillum.rad>illumination.rad
oconv -i hr.oct outside.rad Conv-0.rad illumination.rad>hour.oct
rtrace -h -I -ab 1 -ad 4096 -as 128 -av 0 0 0 hour.oct<mainsamplesupwards.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

Let me know if there is anything wrong with this.

Thank you

Hi!

I am not sure if the software is considering sun angles in calculations.

(...)

set skypar=($mon $day $hr +i $coord)
echo "$month/$day/$hr">>$month.out
oconv room.rad '\!gensky '"$skypar" sky.rad>hr.oct

You are rendering an intermediate sky /without/ sun. Check the manpage
of gensky about how to switch on the sun. Do a test using rvu, looking
up with a fish-eye view - if you do not see the sun, there will be
little contribution for direct sunlight. You can always test the output
of gensky - if there is no light modifier defined called solar, there
will be no sun (which is defined as solar source sun, by the way).

mkillum -ab 0 -ad 1024 -av 0.1 0.1 0.1 hr.oct "<"
windowillum.rad>illumination.rad

I think you do not want -ab 0 for mkillum. You do not calculate anything
here - setting the ambient parameters high, but calculating 0 bounces
(this means nothing) is not very reasonable. If you still have your
blinds there, run mkillum with 2, than 3 and 4, and find out if you have
significant changes.

oconv -i hr.oct outside.rad Conv-0.rad illumination.rad>hour.oct
rtrace -h -I -ab 1 -ad 4096 -as 128 -av 0 0 0

You should be able to reduce -ad here, a much lower value should be fine
and give a great gain in rendering speed.

Let me know if there is anything wrong with this.

Done :wink:

CU Lars.

At a first glance the script seems fine.

But your problem is most likely that gensky does not know about the
absolute irridiance values of a particular sky. It only creates a distribution
pattern with an unspecified total value. If you want to create a sky with
ie. 50000lux you can specify this with one of the -b/-B or -r/-R options.

You can find typical values for the sky illuminance at your location in
climate data files which are available for various energy simulation packages.

Regards,
Thomas

----- Original Nachricht ----

···

Von: G V DEEPAK <[email protected]>
An: Radiance general discussion <[email protected]>
Datum: 23.03.2009 18:38
Betreff: [Radiance-general] Sun angles,

Hello Everyone,

I am trying to find illuminance values on an yearly basis, I am
expecting to get different values for different seasons. Say if we
compare between march nad december, we should get higher values of
illuminance for december as compared to march. But I am getting
almost same values for both the months.

I am not sure if the software is considering sun angles in
calculations.

I am running this script to find the values,

#!/bin/csh -f

set mon=12
set month=March
set day=21
set coord=(-a 30.00 -o 82.35 -m 84)
rm $month.out
while($day<23)
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">>$month.out
oconv room.rad '\!gensky '"$skypar" sky.rad>hr.oct
mkillum -ab 0 -ad 1024 -av 0.1 0.1 0.1 hr.oct "<"
windowillum.rad>illumination.rad
oconv -i hr.oct outside.rad Conv-0.rad illumination.rad>hour.oct
rtrace -h -I -ab 1 -ad 4096 -as 128 -av 0 0 0
hour.oct<mainsamplesupwards.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

Let me know if there is anything wrong with this.

Thank you

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Hi!

But your problem is most likely that gensky does not know about the
absolute irridiance values of a particular sky. It only creates a
distribution pattern with an unspecified total value. If you want to
create a sky with ie. 50000lux you can specify this with one of the
-b/-B or -r/-R options.

While it may be much better to use empirical weather data, gensky will calculate the brightness of the sky dome and the sun from the sun position. So while overriding these calculated values using b, B, r or R may be the way to improve results for a given location, the value given by gensky is not really unspecified. At least I would hope so... :wink:

CU Lars.

···

--
http://www.seris.sg

Thanx a lot ...

···

On Mon Mar 23 14:12:40 EDT 2009, [email protected] wrote:

At a first glance the script seems fine.

But your problem is most likely that gensky does not know about the
absolute irridiance values of a particular sky. It only creates a distribution
pattern with an unspecified total value. If you want to create a sky with
ie. 50000lux you can specify this with one of the -b/-B or -r/-R options.

You can find typical values for the sky illuminance at your location in
climate data files which are available for various energy simulation packages.

Regards,
Thomas

----- Original Nachricht ----
Von: G V DEEPAK <[email protected]>
An: Radiance general discussion <[email protected]>
Datum: 23.03.2009 18:38
Betreff: [Radiance-general] Sun angles,

Hello Everyone,

I am trying to find illuminance values on an yearly basis, I am expecting to get different values for different seasons. Say if we compare between march nad december, we should get higher values of illuminance for december as compared to march. But I am getting almost same values for both the months.

I am not sure if the software is considering sun angles in calculations.

I am running this script to find the values,

#!/bin/csh -f

set mon=12
set month=March
set day=21
set coord=(-a 30.00 -o 82.35 -m 84)
rm $month.out
while($day<23)
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">>$month.out
oconv room.rad '\!gensky '"$skypar" sky.rad>hr.oct
mkillum -ab 0 -ad 1024 -av 0.1 0.1 0.1 hr.oct "<" windowillum.rad>illumination.rad
oconv -i hr.oct outside.rad Conv-0.rad illumination.rad>hour.oct
rtrace -h -I -ab 1 -ad 4096 -as 128 -av 0 0 0 hour.oct<mainsamplesupwards.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

Let me know if there is anything wrong with this.

Thank you

_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general

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Ihre Internet-Sicherheits-Seiten auf Arcor.de bieten alle Infos und Hilfsmittel, die Sie zum sicheren Surfen brauchen! Play it safe!
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_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general

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