[Radiance-general] can we refer to two sky description files in oconv?

[Ji Zhang]

Hi, list,

May I ask if we can merge two skies through one oconv command?

The irradiance value for an unobstructed upward sensor I get from referring
2 sky files in oconv is different from the sum of the two irradiance
values, each of them obtained by referring to just one sky file at a time
...


The problem is described below:

1). I have the following two sky description files:

"sky_12.sky":
# gendaylit 6 22 12 -a 51.15 -o 0.18 -m 0 -W 248.0 427.0 -O 1
# Ground ambient level: 129.0
void light solar
0
0
3 3.649e+06 3.649e+06 3.649e+06
solar source sun
0
0
4 0.009337 -0.464787 0.885373 0.533000
void brightfunc skyfunc
2 skybright perezlum.cal
0
10 6.250e+01 3.978e+01 -0.842096 -1.184194 10.982493 -3.062295 0.268820
0.009337 -0.464787 0.885373
skyfunc glow sky_glow
0
0
4 1 1 1 0
sky_glow source sky
0
0
4 0 0 1 180

"sky_13.sky":
# gendaylit 6 22 13 -a 51.15 -o 0.18 -m 0 -W 250.0 428.0 -O 1
# Ground ambient level: 129.7
void light solar
0
0
3 3.678e+06 3.678e+06 3.678e+06
solar source sun
0
0
4 -0.228410 -0.442326 0.867281 0.533000
void brightfunc skyfunc
2 skybright perezlum.cal
0
10 6.393e+01 3.975e+01 -0.856480 -1.207987 10.711184 -3.050613 0.255098
-0.228410 -0.442326 0.867281
skyfunc glow sky_glow
0
0
4 1 1 1 0
sky_glow source sky
0
0
4 0 0 1 180

2). I run the following shell script and get a irradiance value of  *859.8564
(Wh/m^2)*

"autorun.sh":
oconv ./sky_12.sky ./sky_13.sky > ./sky_12_13.oct
echo '0 0 0 0 0 1' | rtrace -w -h -I+ -ab 1 ./sky_12_13.oct | rcalc -e
'$1=$1*0.265+$2*0.670+$3*0.065' > ./results_12_13.txt

Windows version of the script autorun.bat is:
oconv ./sky_12.sky ./sky_13.sky > ./sky_12_13.oct
echo 0 0 0 0 0 1 | rtrace -w -h -I+ -ab 1 ./sky_12_13.oct | rcalc -e
"$1=$1*0.265+$2*0.670+$3*0.065" > ./results_12_13.txt

3). However, if I do the same by using one sky file at a time I get  *
640.1146* and *640.1624* (Wh/m^2) for sky_12 and sky_13, respectively, and
they're close to the global horizontal radiance in London's weather file
for 22 Jun 12pm and 13pm. The sum of the these two values, which is
around *1280
(Wh/m^2)*, is not equal to the one mentioned above that is obtained by
using the two sky files together in oconv...


Dose this mean that only one sky description is allowed in oconv?  If
that's the case then why the value shown in 2) is not close to either of
the values shown in 3)?

Advises are appreciated!

- Cheers, Ji
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