All results are zero when I enter zero to ambient accuracy

daylight
#1

Hello Everybody,

i have some problems with my daylight simulation.
I want to modify my radParameters, but if i set ambient accuracy to zero every testPoints value becomes zero. Normaly there should be still a higher amount of light than zero if i am not wrong.
This only happens when I use glass surfaces. If I leave the areas blank, I get normal results.
I hope you have any answer to this question.

I registered myself today and for this reason I can not upload anything yet.

Thanks in advance

#2

We need more details to be able to help you. Are you using honeybee or honeybee[+]? Which daylight recipe are you using in this case? Did you get any errors?

#3

Attached you will find the file which has both variants

ambient_accuracy_problem.gh (540.1 KB)

I am using honeybee with the daylight factor simulation and get no errors.

#5

Do you think honeybee [+] could work in a more proper way?
I didn’t try it yet.

#6

Hi @GreenCape

When you set -aa to 0, Radiance turns off ambient caching. This dramatically changes the way Radiance performs the calculations, as a consequence, you need to change a couple of other parameters to get accurate results. One of the most important setting is -lw. When you set -aa to 0, always make sure that -lw is to a very small number (such as 1e-6). You can do it in your definition in honeybee like shown in the image below:

This should fix your problem.

Good luck!

Best,
Hamza

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#7

Hi MohammadHamza,

thank you for your answer.
It solves my problem!
Is there a good composition for the respective parameters and how they react to each other?
It is very important for me to understand all the parameters to make a meaningful calculation.

Thank you in advance

#8

See Radiance’s rtrace manual for documentation of different parameters.
https://floyd.lbl.gov/radiance/rtrace.1.html

Also see this crash course on Radiance ambient calculation:

https://www.radiance-online.org/community/workshops/2014-london/presentations/day1/Mardaljevic_AmbientCrash.pdf

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