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Atmospheric data for sky generation

asked 2025-07-06 16:31:43 -0500

cy's avatar

updated 2025-07-07 10:24:40 -0500

Hi,

I'd appreciate your help with the following. I've been exploring the use of Radiance for sky generation, I've found a problem when using genssky, I get the error:

system: cannot find data file 'Sky/atmos_data/tau_ms_mie_ca_0.12.dat':No such file or directory.

However, the directory and the file exists, but just part of the data is generated (apparently), as is the process was interrupted. The four files in the atmos_data folder are:

irrad_ms_mie_ca_0.12.dat (181 KB); scat_ms_mie_ca_0.12.dat (11,521 KB); scat1m_ms_mie_ca_0.12.dat (11,521 KB); tau_ms_mie_ca_0.12.dat (2,881 KB);

The contents in the files is only one column with thousands of values, and only 3 or 4 values in a second column. I copy the command below:

genssky 6 17 8 -a 53.4666 -o 2.2333 -m -0 -c 1 -n 4 -f June8am -p ./test_hsr

Might this be a problem of memory in the pc? It has 8GB RAM and also sufficient storage space. I'd appreciate any suggestion! Thank you!

-Steph

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It seems you're storing the files at Sky/atmos_data but your command indicate you are storing it at test_hsr. can you run:

ls

genssky 6 17 8 -a 53.4666 -o 2.2333 -m -0 -c 1 -n 4 -f June8am -p ./test_hsr
Taoning Wang's avatar Taoning Wang  ( 2025-07-11 22:51:54 -0500 )edit

I appreciate your help, I corrected the destination file so the problem was solved, however, once I obtained results another question came up, I explain below as it is part of the same topic, I hope is valid.

cy's avatar cy  ( 2025-07-15 16:36:12 -0500 )edit

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answered 2025-07-15 16:35:35 -0500

cy's avatar

updated 2025-09-23 15:39:03 -0500

Thank you! atmos_data is now complete, I corrected the file destination, which was indeed the problem.

I would also like some help with the results I obtained, the command below represents a cloudy sky mid-latitude (same location).

gensky 12 21 12 -a 53.466 -o 2.2333 -m 0 -n 4 -r 256 --f test_hsr.hsr  > ssky.rad

after the octree, I used:

echo 0 0 0 0 0 1 | rtrace -ab 8 -ad 16384 -as 4096 -co+ -cs 20 sky.oct

If I plot it I have a spectral profile (20 samples) high at the end of the spectrum. This is an overcast sky, so I was expecting a rather uniform profile (higher at shorter wavelengths) and not that high values, as I'm assuming is W/m² perhaps I need to normalize it but not sure against what.

I add the plot with -c 0 just to compare, but resulted in similar profiles.

image description

I'd appreciate any comments, thank you!

-Steph

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With latest genssky, the results goes from 780-380, is that how you plot it?

Taoning Wang's avatar Taoning Wang  ( 2025-07-15 16:48:02 -0500 )edit

I plotted 380-780, as I wasn't aware of that, but if the results are 'flipped' the profile makes sense, as it peaks at ~460nm, thanks a lot, I appreciate your help!

cy's avatar cy  ( 2025-07-16 16:33:09 -0500 )edit

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Asked: 2025-07-06 16:31:43 -0500

Seen: 619 times

Last updated: Sep 23