[Radiance-general] Spherical sensor

[Minki Sung]

Hi Greg,

I am sorry for my too late response to your kind comment. I read your
script and it is so helpful. I am using Radiance to calculate ultraviolet
intensity. So I don't need to convert radiance to illuminance, but need to
revise the script for multiply points sampling.
Thank you as always.

Best,
Minki


-----------------------------------------------------------

Hi Minki,

If this quantity is equal to the integral of luminance over the full
sphere, then it would be the same as 4*PI times the average luminance in
all directions.  You can compute the latter quantity by averaging the
output of an appropriate rtrace calculation of random rays over the sphere.
 Something like the following should work:

set N=10000
set orig=(0 0 0)
cnt $N | rcalc -of -e 'Dz=1-2*($1+rand(.77-.61*recno))/'$N -e
'phi=2*PI*($1+rand(-.10+.39*recno))'/$N \
               -e 'rxy=sqrt(1-Dz*Dz);Dx=rxy*cos(phi);Dy=rxy*sin(phi)' \
               -e "Ox:$orig[1];Oy:$orig[2];Oz:$orig[3]" \
               -e '$1=Ox;$2=Oy;$3=Oz;$4=Dx;$5=Dy;$6=Dz' \
       | rtrace -h -ff [options] scene.oct \
       | total -if3 -m \
       | rcalc -e '$1=179*4*PI*($1*.265+$2*.670+$3*.065)'

This should take ray samples in a stratified random spiral over the sphere.
 The 3 averaged radiance values (RGB) output should be multiplied by 179
and 4*PI as above, unless I misunderstand the definition of spherical
illuminance.

Best,
-Greg

> From: Minki Sung <minki.sung at gmail.com>
> Date: December 14, 2011 7:02:14 PM PST
>
> Hi all,
>
> I am calculating spherical illuminance(lux) or irradiance (W/m2), that is
the irradiance of a small spherical sensor in a room. I think it might be
possible if the cosine-correction process for light meter is modifiable. Do
you have any idea?
>
> Best,
> Minki


-- 
Minki Sung, Ph.D.

Building Technology Team
Korea Institute of Construction Technology
TEL.+82-31-9100-586
FAX.+82-31-9100-361
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.radiance-online.org/pipermail/radiance-general/attachments/20120420/f439c746/attachment.html>