Only one mia light surface will work at once

# 1 04-01-2014 , 03:12 PM

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Only one mia light surface will work at once

I'm lighting a nocturnal scene by making various objects (street lamps, neon signs, etc) emit light, using mia light surfaces attached to mia material x. The problem is that I can only seem to use one glowing material in my scene at any one time. As soon as I introduce another, the first one stops working. I thought this might be a memory problem but I've upgraded from 6GB of RAM to 16GB and still have this problem. I'm running Maya 2011 on a four Intel core Mac Pro on OSX 10.5.8. Any ideas?

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# 2 04-01-2014 , 04:10 PM

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Why are you making it so convoluted in your approach....? To me theres clearly no understanding why you are doing it, hence the reason for your problem

If I was lighting lamps and neon signs, I'd just add a lambert or a blinn to the surfaces with incandescence cranked up and add color to ambient channels...far easier to control...

This is the problem with CG, people go down the dark path without the understanding of the basics and get in a mess....try the simple approach

Jay

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# 3 05-01-2014 , 04:19 AM

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This is how I'd approach it.

Use actual lights(non specular emitting lights so they don't show in the reflections) along with the mia_mat and light surface since the self illuminating shaders have limited ability to light a scene. Have the light drive the intensity and color of the light surface. Do the glow in post.

And you most definitely can use more than one light surface in a scene.

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# 4 05-01-2014 , 12:00 PM

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nice one Gen

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# 5 05-01-2014 , 01:57 PM

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Thanks for the replies. I want to make the scene as photorealistic as possible and most of the tutorials I have seen have pushed me towards Mental Ray and mia materials for this. Perhaps I don’t need to rely so heavily on making geometry emit light but it’s frustrating that I can’t get this to work. I’ve actually come across a number of strange issues of things just not working properly and suspect it’s because I’ve been working on this scene for a number of months and it’s become an extremely complex one with numerous objects and textures and some errors have accumulated over time.

I am using lights with IES profiles for the streetlights so there will be some other light in the scene. Plus there is some residual light from a physical sun and sky with the light angled so that the sun is just below the horizon. I’m doing the glow in the scene, using a lambert because I understand mia materials don’t offer this effect. Is there any particular reason why you say I should do this in compositing?

I’m not sure, Jay, why you consider my approach so convoluted. I’m doing pretty much the same as you’re suggesting, only using mia materials.

Gen, if I’ve understood you correctly, you’re suggesting I reflect a light with the appropriate colour off the mia material and light surface in order to make it illuminate the surrounding area more effectively. Is this correct?

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# 6 06-01-2014 , 08:05 AM

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Thanks Jay user added image

BuzzinFly, I'm saying to use lights as usual and have the the light surface only serve to give the light sources a physical representation. Pretty much what it says here in the help files.

As for glow in post, in my opinion its better this way because:

- Baking it into the raw render locks you into a certain look unless you re-render. It's a post process effect even inside Maya(which is why you can't see it until the render finishes)

- There is one shader glow in Maya so its the same behavior for all glows

- There are much better looking glow effects to be had in external packages

- Genny
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# 7 06-01-2014 , 12:18 PM

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Thanks for the clarification, Gen. I'll also consider doing the glow effect in post, as you suggest. Right now, I'm pretty happy with the results I'm getting from the mia material and light surface without supporting it with an additional light. I just wish I wasn't limited to one mia surface in my scene, which for some reason I seem to be. Annoyingly I seem now also to be having problems getting my lights to cast shadows, though I know perfectly well how to achieve this. Perhaps this is one of the pitfalls of making a complex scene - you get weird glitches which no one can explain.

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# 8 06-01-2014 , 12:33 PM

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Buzz, I think it was the way it was written it came across as convoluted

Jay

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# 9 07-01-2014 , 01:49 PM

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Gen, can you suggest software I might use for creating glows in post? I'll be using After Effects for the compositing.

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# 10 07-01-2014 , 06:02 PM

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After effects is fine for creating glows: https://www.google.ca/search?q=creat...sm=93&ie=UTF-8

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# 11 07-01-2014 , 10:53 PM

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Indeed AE can pump out some pretty nice effects. First page on Google search landed me a Video Copilot link. Even if you create complex layered effects at least you can save them as presets and to me, that's another reason why its better than the Maya glow.

You will however need a mask layer which is easy enough with Mental Ray. I think there was a tut on here about material id passes.

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Only one mia light surface will work at once

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