Light passing through cube

# 1 29-10-2013 , 12:49 PM

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Join Date: Oct 2013

Posts: 3

Hey,

I am trying to set up a scene where a Rubic's cube seem to emit the light. The thing is that I don't want the cube to be like a light bulb and shine but simply to emit light onto Wall-E and the surroundings. I have taken a sphere and assigned a mia_light_surface to it to get the effect I am after.

My problem now is I want to place the sphere inside the cube so none of the lighting shows on the cube but only around it.

Is there a way to get the cube to let the light pass through it without lighting it up?

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# 2 30-10-2013 , 12:26 AM

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Join Date: Dec 2006

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In this case you could try using a real light source then unlink the cube from it, or set the cube not to cast shadows (in the render stats of the shape tab). This way you get true shadows with the FG to help with the indirect illumination.

- Genny
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# 3 30-10-2013 , 04:31 AM

The Nurb Herd
Join Date: Oct 2007

Location: London

Posts: 2,381

why not apply the light surface to the cube? i'm a bit lost.

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# 4 30-10-2013 , 09:01 AM

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So should I remove the sphere and just try a regular light source instead? Any specific light? Isn't there a way to remove the cube from being affected by the sphere inside it?

When I use IPR-rendering my "light sphere" does not show up, it doesn't act like a regular light. Could that be why turning of cast shadows and recieve shadows does not work on the cube outside the sphere?

I have been following this tutorial for the "light sphere":

How to emit light from Objects in Autodesk Maya [Full HD] - YouTube

Applying it directly to the cube removes any texture on the cube itself and makes it a bright white color.

I am self-taught and experimenting with lighting is my next project, so forgive me if I miss obvious things and ask stupid questions.

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# 5 30-10-2013 , 11:28 PM

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Join Date: Dec 2006

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Posts: 3,522

Dom, he doesn't want the cube to brighten up.
----
Barrie, there are no stupid questions, especially when dealing with Mental Ray for Maya haha user added image

. I'm giving you a heads up now, strange and frustrating happenings will litter your path to learning Mental Ray, it's powerful but not the most user friendly.

Ok apart from the video being a bad tutorial another issue is trying to light a scene entirely with light surface shaders. The Final Gather settings would have to be tuned pretty high to avoid blobby shadows and even then you'll have only so much control because they are not real shadows(and no, turning off cast or receive shadows won't work there for that exact same reason). Also, using an object to emit light without appearing to do so pretty much defeats the point of using the light surface shader to begin with.

I'm biased so I'd say a mental ray area light (which is just a regular area light with "use light shape" turned on in the mental ray section) but even a regular point light would be better than the surface shader for this.

Also check out light linking.

- Genny
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Light passing through cube

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