Blocking < 20 deg CIE overcast sky

radiance-general
1

Hi,
I would like to block ( no light emission from) the lower part of the CIE overcast sky ( < 20 degrees with the groundplane).
How would I do that,

Thanks for any help,
regards
Jur

2

Hi Jur,

I am not too familiar with Daysim myself, but since it does a daylight coefficient calculation for the diffuse sky, you should be able to “cut” the source representing the sky hemisphere. Some something like replacing

skyglow source skyHemisphere
0
0
4 0 0 1
   180

by a truncated hemisphere:

skyglow source skyTruncHemisphere
0
0
4 0 0 1
   170

Now rays pointing to zenith angles above 170 deg (so anything near the horizon) will never miss the receiver source and should return zero contributions.

As mentioned, I cannot test this myself, so this is just a starting point for you to try out.

Best, Lars.