How to configure Radiance for direct daylight only

radiance-general
1

Hello everyone!

I am currently working on having only the direct daylight in my calculations. Specifically, I am using a fully overcast sky model, but I need to include direct sunlight as well for my analysis.

I understand that setting the -ab parameter to 0 in Radiance will exclude ambient bounces and indirect light.

What is the recommended way to configure Radiance parameters to focus only on direct daylight (using the -ab, -aa, -av, etc. parameters)?

Thanks in advance!

2

Hi @pavlek86,

Your question is somewhat confusing. If you have a fully overcast sky, then by definition there is no direct sunlight.

Perhaps you mean you would like to know how much daylight is received directly from the sky without any reflections. In that case, consider replacing all the materials in your model with black plastic. And running a simulation with -ab 0 (for calculating radiance) or -ab 1 (for calculating irradiance).

3

Yes, you’re right, but I was thinking to support both overcast sky and direct sunlight, sorry for being unclear.

Thanks for the black plastic, really good tip, I’ll try it.

And I’ve already tried with -ab 1, because I need to have values at a specific height of the ground. I think this will cover both cases.

Kind regards,
Pavle