[Radiance-general] Perez Sky for Daylight Simulation
[email protected]
[email protected]
Fri, 28 Mar 2003 19:11:59 +0100
Dear Mr.Ward,
I am student of architecture working an a daylight simulation with
radiance, still dealing with several problems.
I want to generate indoor illuminance values in Lux for a validation
with measured values of an office room.
I am working with the Perez all-weather skymodell in oder to
calculate with a sky which is equivalent to the measured outdoor
conditions.
For input in gendaylit I use the measured direct-normal and diffuse-
horizontal- illuminance [W/m�].
# gendaylit 1 11 12.00 -a 51.30 -o -7.28 -m -15 +s -W 154 93
# Ground ambient level: 11.1
void light solar
0
0
3 9.684e+005 9.684e+005 9.684e+005
solar source sun
0
0
4 0.156133 -0.946576 0.282165 0.533000
void brightfunc skyfunc
2 skybright perezlum.cal
0
10 2.411e+001 3.396e+000 -1.254300 -0.605648 10.900086 -
3.202346 0.012553 0.156133 -0.946576 0.282165
Then I add the sky description from gensky by preparing the octree
skyfunc glow sky_glow
0
0
4 1 1 1 0
sky_glow source sky
0
0
4 0 0 1 180
rtrace is running with the option -I and the following parameters
-ab 4 -av 0.10 0.10 0.10 -ds 0.15 -aa 0.15 -ad 512 -ar 128 -as 256 -
dc 0.50
-dj 0.7 -dp 512 -dr 3 -dt 0.05 -lr 8 -lw 0.002 -sj 1 -st 0.15
To obtain results for illuminance I execute rcalc for the coordinates
of the real measured points using a function I found in the mailing
archive
rcalc -e '$1=47.435*$1+119.93*$2+11.635*$3'
Unfortunatly I don't obtain reasonable results, neither for clear sky
nor for overcast conditions.
The generated values for the outdoor illuminance at clear sky
conditions are approximately 25% lower and at overcast
conditions 40 % higher than in reality.
The generated values for the outdoor illuminance are converse and
also definitive non equivalent in their progression.
It would be kind if You could help me.
Regards, Jorg Escher
University of Dortmund
Chair for Environmental Architecture
0049.231.755.54.25
[email protected]