Exact effect of a 40 watt fluorescent light

andybot

Guess I never thought of that, you could grab and IES file for a tubular light. Andybot, if you have one, can you share with the class ?

Well, that's just the issue - ies as it is currently implemented in vray is a point source. The ies profile would have to be "stretched" along the length of the tube for it to represent a fluorescent bulb. You can only get sharp shadows from an ies source currently.

rspierenburg

So with the model shown above, what effect would you get if you completely incased the tube in 6 rectangular lights? Sort of a Cubic light if you will.

andybot

I played around with simple rectangular lights, here are some results. You can see the light pattern is different depending on how many facets you make with the rectangular lights. It ends up with a bit of a hotspot on the ceiling using 5 planes, I actually think the 3 planes turned out better. The thing I made different from what valerostudio showed above is that I made the rectangular lights much larger than the bulb in order to get a softer more spread out effect. I have the lights set as hidden in vray.

valerostudio

Andybot, nice work. The thing that we need to disclaim here is that nothing we are showing you is the "exact" effect of a 40w bulb. I am fairly certain this cannot be done in Vray, unless I am wrong. You can give an light a Watts setting, but I dont think this is directly related to how a real bulb works. Someone correct me if I am wrong here.

andybot

@valerostudio said:

Andybot, nice work. The thing that we need to disclaim here is that nothing we are showing you is the "exact" effect of a 40w bulb. I am fairly certain this cannot be done in Vray, unless I am wrong. You can give an light a Watts setting, but I dont think this is directly related to how a real bulb works. Someone correct me if I am wrong here.

Thanks!
Correct, this is all approximate and relative. With IES files, there is actually a relationship to real values, but even then, the render engine uses an approximation (biased)

pilou

There is not a tool for that in Light Up ?

valerostudio

I have no experience with Light-Up but I think only an unbiased rendering engine will give you "real" world results.

nomeradona

if its using wattage then biased render cant replicate that.

nomeradona

andy that is cool tests.

john2

what is biased rendering and unbiased rendering??..and andybot. awesome effect.

valerostudio

I think this article has the basic answers to this question.
http://galaxycityradio.com/2012/01/04/biased-vs-unbiased/