Black Light - how?

[Tim Nelson]

I never even thought of this before, but now I have a project with black lights in it. How in the heck do you do something like that? I haven't started pulling my hair out yet, but I probably will in the near future.

 

The lighting designer made this insightful comment, because I was asking about an IES for it. "The lights are black light and the lamp has no lumens. Therefore it has no rendering properties". So clearly, there is no way to use real world data for this kind of thing, at least not that I am aware of.

 

Any takers?

[Crazy Homeless Guy]

What type of material is it? If it is glass, I think you will probably need to be a little more accurate. If it is a graphic that is simply illuminated from behind, or say, a thin veneer of Onyx then I approach it in a different way. I paint a map in Photoshop using dark's or blacks where I want less illumination, and lighter colors where I want illumination. I then drop this into the illumination slot on the material that is applied to the sign. This is the quickest way I know, and will work perfectly if you are not to close to the sign.

[quizzy]

Travis, he means bLack light not back light. ;-)

 

hmmmm... interesting light that blue-ish black light. What you could try is to place an ordinary light that only includes the white diffuse compnonent in the material in the scene.

Dont even think the "un"biased render engines can do it.

[Tim Nelson]

Hey Travis, you know I said black light, not back light, right? You reply sounded more light back lighting. If I'm wrong, sorry.

 

At any rate, it is a general area that is being illuminated by black fluorescent lights. Ok, it's a bowling alley. I don't really have any other bright ideas other than to super saturate a vray light. It sort of works as you can see in the crop here, but would not have the same effects that a real black light does, where light colors are the only ones that seem to be affected.

[Tim Nelson]

What you could try is to place an ordinary light that only includes the white diffuse compnonent in the material in the scene.

Thats a good idea. I could do two sets of lights. One that affects lighter objects, with a higher multiplier, and then a 2nd light which only affects the dark objects with a much lower multiplier. Or only do the light objects and the the dark objects pick up the bounced light...

[quizzy]

http://en.wikipedia.org/wiki/Black_light

 

so basically, light your scene, get the objects with the fluorescent materials (or the ones you want to be fluorescent, then add a light that only includes those objects, and crank up the brightness.

[Crazy Homeless Guy]

I guess I need to slow down a bit, and read a bit more closely. Yes, I read back light.

[quizzy]

http://upload.wikimedia.org/wikipedia/en/d/d0/Midnight_bowling.jpg

[Justin Hunt]

glad I had a look at this one, O too am about to do a bowling alley, ( it's in a house, dont ask:p)

 

Would a little self illumination work?

 

jhv

[quizzy]

glad I had a look at this one, O too am about to do a bowling alley, ( it's in a house, dont ask:p)

 

Would a little self illumination work?

 

jhv

 

as long as the black-light does not cast shadows you can just do this with self-illum...

[Peter M. Gruhn]

Self-illum is what I'm just opening Max now to test. iiuc, all that's really going on with black lights is the bulb emits a frequency we can't see and the material picks up that light and returns it at a frequency we can see. From a purely energy transfer point of view, I guess it isn't, but from a "what humans think they see" angle, it sure sounds like SI.

 

...

 

Ah, here's the rub. Fluorescence still relies on illumination so it's possible to be in shade. So I did an rgb multiply of my self illum colour (gradient map) and a light/shadow falloff with the output cranked in heavy favour of the white for the falloff. It's a start.

[Jeff Mottle]

Here's some reading for you: http://www.cis.rit.edu/fairchild/PDFs/PRO03.pdf

[Tommy L]

I think its also known as a 'Dr. Zeuss' light.....!!!

 

"...phosphor typically used for a near 368 to 371 nanometer emission peak is either europium-doped strontium fluoroborate (SrB4O7F:Eu2+) or europium-doped strontium borate (SrB4O7:Eu2+)"

 

Good luck when they ask for a photo-real lighting analysis....

[Tim Nelson]

Well this old dog just loves his vray lights. And since the black light was mostly over the lanes themselves and there are other normal lights in the scene, it's really not as complicated as I was thinking. Probably could be better using other techniques, but this is how it turned out.