View Full Version : Realistic Ocean Caustics..

03 March 2003, 07:28 AM
Does anyone know how I would get realistic caustics on a surface underwater?
I have been using the 'Underwater' procedural on the underwater objects, but there are so many, and sometimes it looks odd where the textures meet object edges.

Is there any way to actually get the water to make caustics?
Below is an image of where I'm currently at.. I've tried everything and I'm nearly at the 'I'll pull all my hair out!' stage...:D

03 March 2003, 07:39 AM
hmm, there are a couple ways to do it. Texture map the light so it projects the caustic effect. Or model the ocean surface and animate it with a displacement map and turn on caustics under the lights - global illumination panel. check for a tutorial, I think i saw one there......
anyway hope i helped...

03 March 2003, 08:28 AM
Thanks, but all the tuts on Caustics are down except one, which uses Mental Ray, so I'm guessing the pages are gone...
But thanks anyway.
Anyone with more suggestions?

03 March 2003, 08:33 AM
theres a free tute at simplylightwave, might help

03 March 2003, 09:19 AM
Thanks, I'm signing up to have a look around.
I know that in Maya, caustics isn't that hard to simulate, I did download the Ocean_Caustics movie, it looks really cool.. There must be a simple solution, maybe it's all to do with the water surface.
It would be ultra-cool (ultra's a good word...:buttrock: ) if you could get those strips/rays/beams/shafts of light to appear under the water's surface.. Like in Finding Nemo. Anyone seen that? (Or the trailer?) That looked so amazingly good..
You could probably get that effect using volumetric lights, but the rendering time would be horrific!
The problem stands...

P.S, if I do find a really good solution, I'll post it as a tutorial if I can.

03 March 2003, 09:53 AM
i think I would suggest if your doing an animation, that you maybe render a displacment or similar animation and comp it in an editing program, over your sea scene.

your right one frame OK, an aniamtion with all volumetrics, wheeeeew,:eek: render time.


03 March 2003, 12:43 PM
I had pretty good results by doing the folowing:
I modeled a flat plane, made it bluish and applied the underwater- procedural to the color- channel (give this a bright color, maybe even white). The plane has to be 99% transparent and you need to apply colorfiltering 100% to it. Then place t right below the main- light.
In an alternative technique you may also try using the underwater- procedural in the transparency- channel and so vary the light- intensity instead of the light- color.
Hope that helps.

03 March 2003, 01:43 PM
how deep is your scene supposed to be? The reason I ask is because caustics on an ocean floor to be visible has to be very shallow with crystal clear water with no or little debris and nutrients. If you are making a scene that is supposed to be 35 feet and deeper I wouldn't bother with caustics and show the underwater feel in a different way. If you decide that you still want caustics to a scene that might be very deep you run the risk of ending up with an image that looks like objects are miniatures.

BTW the "God rays" effect can be done with a very large point light lens flare.

03 March 2003, 10:59 AM
Thanks a heap everyone. Your comments are all really helpful and I'm trying them all out now.
It's a tricky thing to do.. I found that, as anieves said, the caustics work fine in shallow water, but get past a few feet and they vanish..
I'm still trying..

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