Introduction to Maya - Rendering in Arnold
This course will look at the fundamentals of rendering in Arnold. We'll go through the different light types available, cameras, shaders, Arnold's render settings and finally how to split an image into render passes (AOV's), before we then reassemble it i
# 1 19-04-2011 , 06:07 PM
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Rendering Volumetric Clouds/Ray Marching/ Volume Sattering

Hello, I have a scene in a temple and I really need to have some raylights which make the dust particles visible. I've done a pretty big research, but most of the info i got was for old maya versions (before v.7).

What i do is to make a volume container for the lightrays, assign a transmat in the mental ray shader-override for material and shadow, then add a Parti_volume node for the scattering. So far, so good, after some tweeking and adding a physical light node into a maya lght I get a pretty decent image like the attachment (ignore the wierd shadows). The PROBLEM is, that if i want to get smooth results, i need a pretty BIG container... and i CAN NOT enter with the renderable camera into the volume container. It just doesnt render the light... I have tried adding another light with photon emission into the container, than adding a photon_parti_node into his photon-volume attribute... but still doesnt work. I will be very glad, if there is some experienced mental ray artist (or just anyone who knows what I am talking about user added image ), who can help me solve this problem,. Thank you!

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# 2 20-04-2011 , 02:21 AM
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I don't get the problem. Apart from the mix/max step lens attribute on the partiVolume, volume container size and grain are unrelated as far as I know plus I don't see any noise in the render. I don't use the "physical light", a regular Maya light with a quadratic falloff is more accurate so I don't know if that is part of the problem, it could be dying before it gets a chance to illuminate the scene. I can't imagine why the camera being inside the volume makes the lights not render :s.

This is a render that is using a renderable camera and it's inside the volume primitive.

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# 3 20-04-2011 , 01:03 PM
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This is really nice render! Do you use anything except parti_volume? Again, I tried just a really simple setup - cube container (material transmat, parti_volume), 1 maya point light with quadratic decay (and decent intensity of 50). I havent tweeked the party volume node, but the problem still persists: When the camera is outside the container - theres light, when i cross the bounding box - no light at all!

What could go so wrong? Thank you for the troubleshooting, maybe if you can upload your scene It can be helpful too.

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Last edited by xukca; 20-04-2011 at 01:06 PM.
# 4 21-04-2011 , 03:47 AM
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Actually I was just about to ask you to upload yours as it would make it easier to pinpoint what got messed up.


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# 5 21-04-2011 , 04:08 PM
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Oh well...I just realized, that maybe i havent had anything as background, to actually see the rays... Because these rays does get rendered on top of something else, they dont have its own alpha. After I did a closed interior shot, there are no more problems seeing the scattering, when the camera is inside the container. (actually if i get closed interior my camera SHOULD be inside to render it, lol...) Thank you for the assistance, helped me to clear this up user added image

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