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View Full Version : Prismatic rainbow caustic effects - can it ever be done?



DonJMyers
09-20-2012, 01:22 PM
Shine a bright white light through a prism and it breaks it into caustic rainbows which are cast on a nearby surface.

Rainbow surfaces like compact discs can finally be simulated with complex nodal shaders but what about rainbow caustics?

LW caustics (which people complain about) can make whitish caustics through glass or golden caustics from golden shiny metal. But nothing truly makes these rainbows. This is not a criticism as I don't think any program can do it out of the box.

Can it be done and what is the basic math behind it?

Some of the nodal shaders make rainbow refractions inside clear objects but that is not the same as projecting colored light.

I notice LW cannot make a discoball hit with light shoot out beams of dots around the room either. I assume it is the same problem. Something tells me when programs can finally sim these fine points render times will get really long!

macb
09-20-2012, 01:37 PM
Haven't tried it myself, but might be able to create a similar effect with this plugin.
http://www.evasion3d.com/sp_lw_intro.html


Shine a bright white light through a prism and it breaks it into caustic rainbows which are cast on a nearby surface.

Rainbow surfaces like compact discs can finally be simulated with complex nodal shaders but what about rainbow caustics?

LW caustics (which people complain about) can make whitish caustics through glass or golden caustics from golden shiny metal. But nothing truly makes these rainbows. This is not a criticism as I don't think any program can do it out of the box.

Can it be done and what is the basic math behind it?

Some of the nodal shaders make rainbow refractions inside clear objects but that is not the same as projecting colored light.

I notice LW cannot make a discoball hit with light shoot out beams of dots around the room either. I assume it is the same problem. Something tells me when programs can finally sim these fine points render times will get really long!

stiff paper
09-20-2012, 04:36 PM
http://forums.newtek.com/showthread.php?42148-New-Prismatic-Caustics-plugin

erikals
09-20-2012, 08:07 PM
 
alternative method > http://forums.newtek.com/showthread.php?t=66218

do-able for stills, but for animation it's tricky (looong rendertimes)

DonJMyers
09-20-2012, 08:58 PM
Thanks everybody!

jwiede
09-20-2012, 10:31 PM
LW caustics (which people complain about) can make whitish caustics through glass or golden caustics from golden shiny metal. But nothing truly makes these rainbows. This is not a criticism as I don't think any program can do it out of the box.
Actually most "unbiased" renderers (Maxwell and that camp) can do so easily, and other renderers that support "optical dispersion" caustic effects can do so as well, to varying levels -- Vray and Modo both support such effects, to name two.

(edit) IIRC, Kray (for LW) also now supports such dispersion caustic effects as well. Perhaps use Kray?

erikals
09-21-2012, 03:23 AM
one of the best programs for this is actually LuxRender.
LuxRender is free :]

12min per frame in 720p >
http://www.youtube.com/watch?v=wD3OZ4xXwRM

erikals
09-21-2012, 03:40 AM
this would be nice > Real-time caustics
http://www.youtube.com/watch?v=ajEj1A0FVGI

open source i believe...

jwiede
09-21-2012, 01:49 PM
I seem to recall someone had a nice way of faking it in LW in the past, using color gradients->IOR adjustments, but can't find the details right now (search is being...uncooperative). Anyone else recall any of the details?

erikals
09-22-2012, 11:14 AM
post #4 does this, but technique flickers for animation.

v1u1ant
09-23-2012, 04:06 PM
Seems to be straight forward with Vray.
http://www.youtube.com/watch?v=Zys-yKIt-ls


Still, I would like to understand how to achieve this in LW. The other threads pointed at here dont seem to explain it so well, at least not for me.