Volume Caustics in Autodesk Maya 2013


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A description is presented of a simple procedure for creating volume caustic effects beneath a water surface (visible light rays in the volume beneath the water surface) produced by refracted light rays. The effect is achieved using two mental ray shaders, parti_volume and parti_volume_photon.

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20 responses to “Volume Caustics in Autodesk Maya 2013”

  1. Very useful tutorial. But, I have one question.

    I’m creating a room under the sea.
    The camera is in front of the room and the roof is water surface.

    If I use a directional light and tilt it like you did in this tutorial, caustics will only appear on the floor, back, and one of the sides.
    I want all of the planes to have caustics, so I tried using other lights such as point light and spot light, but none of these seems to emit caustics…
    Do you have any suggestion on how to get all the planes to receive caustics?

  2. Go to the "find" menu under the help tab, I think you can find most of the options (in different locations compared to Maya 2013).  If not write  me back and I will reproduce the tutorial and let you know where to find things.

  3. Wow, thank you so much for posting this tutorial. All the other tutorials online for these nodes have me producing 5-hour frames, but now I'm rendering in ten seconds. Big sarcastic thank-you to mental ray for its lack of documentation, and big serious thank-you to Samuel.

  4. I think you are referring to the background appearing in a render if the transmat shader is not applied to the background. I don't see any advantage to the background appearing in the render. Its function is to enable the volume caustic effect to render.

  5. Haven't tried this but it would seem simpler just to use the background object with parti_volume and transmat shaders attached (so the background does not render), then make your tiled pool using separate objects.

  6. You might get the effect by using maya fluids to produce a merkey water effect. See the blog by Duncan on Autodesk Area ("Torpedo bubble trails with maya fluids"). The light rays might fade with distance from the camera.

  7. @Sliles12yt, Thank you for this tutorial. If you would be so kind as to describe how one would control the depth of the rays without effecting the quality of the atmosphere. I was creating a much larger scene and your settings do work at the scale that I am working. Ive tweeked every setting I can think of and it seems like I brake the effect with just a few number changes. Thank you

  8. Well, it's nice to know that it works without the transmat and the dummy box, that you can use the environment to double as your volumetric material as well. It's all of course dependent on what you wanna create. Thanks for a good and informative video! 🙂

  9. I forgot to mention in the video that a transmat shader was applied to the background material. If the transmat is removed the background plane will appear in the render.(along with any texture applied to it). It may be simpler to keep the background plane (with transmat and parti_volume shaders) separate from the objects you wish to show up in the render.

  10. That's curious… I always thought that you needed a box surrounding the volume you'd want to render in order to get volumetric lighting. Judging by this video, you only need geometry with the volumetric shaders at the same angle (from the camera) as you'd want your volumetric effect. So, in essence, if I were to make a tiled pool, I could make the tile shader double as a volumetric shader as well, instead of encasing the entire thing in a volume box and using the old transmat-material solution?

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