Dear Radiance experts.
I am professionally using radiance for calculating daylight factors and illuminance. It all works quite well. However, I can not fully understand how to use ambient files.
Question 1: Is there any comprehensive documentation on the topic?
Question 2: It seems to me that when rtrace is used with ambient files, a higher value of illuminance is calculated than when no ambient files are used. Is there any explanations to that? Which value is more correct?
I have put together a simple example that illustates the problem. Since I am a newbie in this forum and I can not attach files, I post them here directly. All the files below need to be saved into the same directory. The run.bat file needs to be run and the result is printed to the file res.txt.
materials.mat
void plastic walls
0
0
5 0.5 0.5 0.5 0.002 0.3
void glass windows
0
0
3 0.7 0.7 0.7
zone1.rad
walls polygon zone1.1540
0
0
12
1 0 0
1 0 1
0 0 1
0 0 0
walls polygon zone1.4620
0
0
12
0 0 1
0 1 1
0 1 0
0 0 0
walls polygon zone1.2310
0
0
12
0 1 0
1 1 0
1 0 0
0 0 0
walls polygon zone1.5137
0
0
12
1 0 1
1 0 0
1 1 0
1 1 1
walls polygon zone1.6457
0
0
12
0 1 1
0 0 1
1 0 1
1 1 1
walls polygon zone1.1
0
0
18
0 1 0
1 1 0
1 1 1
0.75 1 0.75
0.75 1 0.25
0.25 1 0.25
walls polygon zone1.2
0
0
18
0 1 0
0.25 1 0.25
0.25 1 0.75
0.75 1 0.75
1 1 1
0 1 1
windows polygon zone1.3267
0
0
12
0.75 1 0.25
0.25 1 0.25
0.25 1 0.75
0.75 1 0.75
zone2.rad
walls polygon zone2.1540
0
0
12
0 0 0
0 0 1
-1 0 1
-1 0 0
walls polygon zone2.4620
0
0
12
-1 0 1
-1 1 1
-1 1 0
-1 0 0
walls polygon zone2.2310
0
0
12
-1 1 0
0 1 0
0 0 0
-1 0 0
walls polygon zone2.5137
0
0
12
0 0 1
0 0 0
0 1 0
0 1 1
walls polygon zone2.6457
0
0
12
-1 1 1
-1 0 1
0 0 1
0 1 1
walls polygon zone2.1
0
0
18
0 1 0
-1 1 0
-1 1 1
-0.75 1 0.75
-0.75 1 0.25
-0.25 1 0.25
walls polygon zone2.2
0
0
18
0 1 0
-0.25 1 0.25
-0.25 1 0.75
-0.75 1 0.75
-1 1 1
0 1 1
windows polygon zone2.3267
0
0
12
0.25 1 0.25
-0.75 1 0.25
-0.75 1 0.75
0.25 1 0.75
shade.rad
walls polygon shade
0
0
12
50 2 0
50 2 50
-50 2 50
-50 2 0
sky.rad
skyfunc glow skyglow
0
0
4 1 1 1 0
skyglow source sky
0
0
4 0 0 1 180
skyfunc glow groundglow
0
0
4 1 1 1 0
groundglow source ground
0
0
4 0 0 -1 180
void plastic groundplane_mat
0
0
5 0.2 0.2 0.2 0 0
groundplane_mat polygon groundplane0
0
0
12
-50 50 0
50 50 0
50 -50 0
-50 -50 0
p1.pnt
0.5 0.5 0.1 0 0 1
p2.pnt
-0.5 0.5 0.1 0 0 1
run.bat
echo This result file is to show that usage of ambient file increases illuminance > res.txt
gensky -ang 0 45 -b 22.86 -c -m 0 -g 0.2 > sky.mat
oconv sky.mat sky.rad materials.mat zone1.rad zone2.rad shade.rad > scene.oct
echo Zone 1 without ambient file >> res.txt
rtrace -ab 5 -h -I+ -ov -u- -faa scene.oct < p1.pnt | rcalc -ia -oa -e $1=179*(0.265*$1+0.67*$2+0.065*$3); >> res.txt
echo Zone 2 without ambient file >> res.txt
rtrace -ab 5 -h -I+ -ov -u- -faa scene.oct < p2.pnt | rcalc -ia -oa -e $1=179*(0.265*$1+0.67*$2+0.065*$3); >> res.txt
echo Zone 1 without ambient file but with large ab >> res.txt
rtrace -ab 50 -h -I+ -ov -u- -faa scene.oct < p1.pnt | rcalc -ia -oa -e $1=179*(0.265*$1+0.67*$2+0.065*$3); >> res.txt
echo Zone 2 without ambient file but with large ab >> res.txt
rtrace -ab 50 -h -I+ -ov -u- -faa scene.oct < p2.pnt | rcalc -ia -oa -e $1=179*(0.265*$1+0.67*$2+0.065*$3); >> res.txt
echo Zone 1 with ambient file >> res.txt
rtrace -ab 5 -h -I+ -ov -u- -faa -af ambf.amb scene.oct < p1.pnt | rcalc -ia -oa -e $1=179*(0.265*$1+0.67*$2+0.065*$3); >> res.txt
echo Zone 2 with ambient file >> res.txt
rtrace -ab 5 -h -I+ -ov -u- -faa -af ambf.amb scene.oct < p2.pnt | rcalc -ia -oa -e $1=179*(0.265*$1+0.67*$2+0.065*$3); >> res.txt
echo The illuminance in zone 2 is higher when using ambient files than without it. Such a high value can not be achieved by using a very large ab. >> res.txt
del ambf.amb
del scene.oct
del sky.mat
