Light > Prism > Dispersion into Spectrum?

Light > Prism > Dispersion into Spectrum?

Post by Jaso » Thu, 24 Aug 2000 12:44:11



Does anyone know how to accomplish the effect of dispersing light into a
spectrum as it passes through glass?

I'm going to have to do it with a large number of surfaces/bevels, so I'd
rather avoid "cheating" with hidden lights and colored gels, etc.

I'll probably be taking my chances with 6.0b Intel for the caustics.

Any advice would be great.

Thanks,

Jason

 
 
 

Light > Prism > Dispersion into Spectrum?

Post by e.. » Thu, 24 Aug 2000 13:30:48


Quote:> Does anyone know how to accomplish the effect of dispersing light
into a
> spectrum as it passes through glass?

> I'm going to have to do it with a large number of surfaces/bevels, so
I'd
> rather avoid "cheating" with hidden lights and colored gels, etc.

> I'll probably be taking my chances with 6.0b Intel for the caustics.

> Any advice would be great.

render in three (or more if you want:) passes with different indices of
refraction, composite afterwards.

i remember someone doing some gems this way.. way back.. walter
turberville perhaps ?

eetu.

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Before you buy.

 
 
 

Light > Prism > Dispersion into Spectrum?

Post by Steve Boye » Thu, 24 Aug 2000 04:00:00


The optical property is called spectral diffusion, Alias PA has a shader
that does this well (for diamond, prism, gem, cd glints).

I think it can only be faked as you have indicated with LW.  Caustics
refract the light correctly, but don't diffuse the spectrum.

Perhaps fancy experimentation with gradient spectrums on specular or corona
channels could pull off a good simulation.

Steve Boyer.


Quote:> Does anyone know how to accomplish the effect of dispersing light into a
> spectrum as it passes through glass?

> I'm going to have to do it with a large number of surfaces/bevels, so I'd
> rather avoid "cheating" with hidden lights and colored gels, etc.

> I'll probably be taking my chances with 6.0b Intel for the caustics.

> Any advice would be great.

> Thanks,

> Jason

 
 
 

Light > Prism > Dispersion into Spectrum?

Post by Will » Thu, 24 Aug 2000 04:00:00



>render in three (or more if you want:) passes with different indices of
>refraction, composite afterwards.

>i remember someone doing some gems this way.. way back.. walter
>turberville perhaps ?

>eetu.

Would it be possible to use a spinning light trick, except with an enveloped
IOR, and light color, and motion blur?

Just checked, and 5.6 doesn't have envelopeable IOR.  What about 6?
---------------------------
"I /want/ Moofeus!"
-The V E C T O R-

 
 
 

Light > Prism > Dispersion into Spectrum?

Post by Jeff Kilgro » Thu, 24 Aug 2000 04:00:00



Quote:> Does anyone know how to accomplish the effect of dispersing light into a
> spectrum as it passes through glass?

> I'm going to have to do it with a large number of surfaces/bevels, so I'd
> rather avoid "cheating" with hidden lights and colored gels, etc.

With LW, You will have to "cheat" because LW doesn't provide any type of
diffusion (and I don't believe there are any plugins available that do) --
as others in this thread have pointed out.  Anyway, give this a try:

Draw an image of your diffused spectrum in a program like Photoshop or
photograph a real one shat is projected onto a white wall or suitable
surface.  Use the image as a projection map for a spot light.  Place
spotlights projecting this map inside your prism wherever you need a
diffused spectrum emission.  You can fine-tune the appearance of the
reflected spectrum on the sides of your prism and on other surfaces by using
the BRDF shader or Worley's Gaffer.

If you need to animate the effect, I would imagine that the same technique
would work, but you may have to produce an animated/changing spectrum map to
get the right effect.  Perhaps a procedural spectrum or adding some
noise/turbulence to your spectrum can accomplish this...

...Just some suggestions...

--
- Jeff Kilgroe : change the .nospam to .com to reply by e-mail!
- Applied Visual Technologies, LLC
- www.appliedvisual.com

 
 
 

Light > Prism > Dispersion into Spectrum?

Post by Chris Golcher » Wed, 30 Aug 2000 04:00:00


On Wed, 23 Aug 2000 21:52:38 GMT, "Jeff Kilgroe"

Quote:>With LW, You will have to "cheat" because LW doesn't provide any type of
>diffusion (and I don't believe there are any plugins available that do) --
>as others in this thread have pointed out.  Anyway, give this a try:

  I had one that was giving results (not all good)  due to the 80
hours a week at work it hasn't seen any work on it for a long time.

  I may bring visual studio up to work (since I don't use it at home
anymore)  and use it as a distraction during the long days.