Dear All,
I am trying to simulate a 'prismatic diffuser' of a flourescent luminaire. Anyone can let me know which would be the best way to model it. Some questions I have regarding this are:
- Is there any material readily available that I can try to use and validate in my case? As I am not very expert in Radiance materials, this would help me to learn things.
- Which Radiance material would define a 'prismatic diffuser' well ?
- Is there any good reference or text to understand well the Trans, Transdata, BRTDFunc etc. etc. diffuser related matters ??
Any suggestion would be fine ....
Thanks,
Sharif
I am trying to simulate a 'prismatic diffuser' of a flourescent
luminaire.
I think the fprism.cal file in Radiance's lib directory may help you. But I also think that this (luminaire modeling) is not really a use case Radiance was developed for, so I do not how reliable results you will get without tweaking parameters a lot. Maybe (!!!) it will help to hide your modeled luminaire behind an illum face (using mkillum) so that you get less noise.
Lars.
I'll second Lars' warning: Radiance is not the best tool to model the light output distribution of a luminaire. Of course, modelling pre-determined light output distributions for luminaires is another matter and Radiance has no problem with that.
See "Development and validation of a Radiance model for a translucent panel" by Reinhart and Andersen for a very thorough description of how to go about modelling translucent panels -- not the same as a 'prismatic diffuser' but should prove informative.
Direct link to paper here:
http://irc.nrc-cnrc.gc.ca/pubs/fulltext/nrcc48165/nrcc48165.pdf
-John
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-----------------------------------------------
Dr. John Mardaljevic
Senior Research Fellow
Institute of Energy and Sustainable Development
De Montfort University
The Gateway
Leicester
LE1 9BH, UK
+44 (0) 116 257 7972
+44 (0) 116 257 7981 (fax)
[email protected]
http://www.iesd.dmu.ac.uk/~jm
Agreeing with the others, Radiance is not the ideal tool for modeling a fluorescent luminaire with a prismatic panel, but it can be done. You have to know a lot of details about the geometry and materials involved, but this is a case where mkillum may work reasonably well. That isn't to say the whole thing is straightforward.
You are much better off either measuring the luminaire somehow, or using an IES luminaire file belonging to something similar.
Best,
-Greg
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From: "Shariful Shikder" <[email protected]>
Date: December 5, 2007 2:10:51 AM PST
Dear All,
I am trying to simulate a 'prismatic diffuser' of a flourescent luminaire. Anyone can let me know which would be the best way to model it. Some questions I have regarding this are:
- Is there any material readily available that I can try to use and validate in my case? As I am not very expert in Radiance materials, this would help me to learn things.
- Which Radiance material would define a 'prismatic diffuser' well ?
- Is there any good reference or text to understand well the Trans, Transdata, BRTDFunc etc. etc. diffuser related matters ??
Any suggestion would be fine ....
Thanks,
Sharif