Rendering Light Bulb Glow

# 1 17-12-2012 , 01:44 PM

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Hello,

I am new here and also have only been using Maya for around 2 months, so please go easy on me! I have followed several tutorials and decided I would have a go at creating something from scratch with no video tutorials etc to guide me.

I tried to create a realistic light bulb. But it doesn't quite look right.
I can't replicate the glow! And the glass looks smudgy?

The first pic is the full light bulb, which looks ok, a little dark maybe.
But the second one is smudgy, the glow of the filament is non existent, I want it to actually shine a little light around the scene, not too much, just to give the idea it is a bulb.

I have used mia material X for the filament and glass, and for the filament used the 'Advanced>additional colour' option to add a mia_light_surface. If i turn the intensity up on this the filament just goes white, if I turn the Fg Contrib up, the filament goes more yellow. There is no glow really on the scene?

Any one know why or can give me a better way to achieve this?

Thanks again!

Justin

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# 2 17-12-2012 , 04:15 PM

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You should really do things like glow in post with Photoshop. Not only will it be faster, but it will give you more control as well.

Imagination is more important than knowledge.

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# 3 17-12-2012 , 04:34 PM

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Thanks for the response, I really wanted a way to achieve it in Maya just so I could animate if needed, Using this as a learning tool! Any ideas on how it can be done with mental ray/lights etc?

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# 4 17-12-2012 , 05:37 PM

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You could assign a surface shader to the object and pipe the 'result' of the mia into the out color of the surface shader using the connection editor and control the glow from that shader. However, doing it in post will indeed give you more control, and it can be animated from there, just get your image sequences to a compositing package like After Effects, Nuke etc.

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# 5 17-12-2012 , 06:09 PM

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Glow is also caused by a number of optical phenomena. One of them is particles in the air. You can create these in mentalray by using the parti_volume shader.

Another few things you can play with:

1) Put a physical lens shader on your camera, which will help "blow out" areas correctly.
2) Attach an mib_blackbody shader to the additional color attribute of the filament's additional color. This will allow you to specify a physical color temperature for an incandescent bulb. (Usually around 3300K) You'll need to push the intensity to some stupid number (something like 1000000) in order to see it properly.

Imagination is more important than knowledge.

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# 6 17-12-2012 , 06:35 PM

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Thank you both,

I will try each of your options just to see the differences really! The lens shader is for creating a depth of field isn't it? Unless I am referring to the wrong one. Well I will have a play and see what I can come up with! I tried one on a previous tutorial but I couldn't get it to focus correctly, it just blurred out the entire image... So i resorted to photoshop. Being a graphic designer by trade I feel more comfortable with that! Just wanted to learn a new skill!

I will be back with my results, either with a 'yay it's worked' or 'nay, i've hit another brick wall'!

Thanks again

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# 7 18-12-2012 , 01:32 AM

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The lens shader does a bunch of other things besides depth of field. It also simulates a real camera; so you have exposure, aperture, ISO, etc.

Imagination is more important than knowledge.

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# 8 18-12-2012 , 04:00 PM

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Have never used the mib_blackbody before, so did a quick render with one at 3300K and intensity 10. I had not used a lens shader either and I think it adds nice realism.

Thanks NextDesign.

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# 9 18-12-2012 , 05:45 PM

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No problem Charles. mentalray is full of these neat little features, but they aren't documented that well, so it's difficult to know how to connect things properly.

Another interesting thing you can do is with a light, go to it's attributes, and under the mentalray light shader, map a "physical light". In the color, you can use a black body as well. It can make some nice effects as well.

Imagination is more important than knowledge.

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# 10 18-12-2012 , 07:02 PM

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Oh yes - I remember hearing about that - but it went over my head at the time.

I think that might work nice for a lamp and a light bulb, maybe add some volumetric fog as well would create a nice scene. Was meaning to try that at some stage.

Problem is all these things are nice for stills I'm guessing, prob expensive for animations?

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# 11 18-12-2012 , 07:37 PM

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This looks good, I am currently trying a render but have had to turn the final gather up as the light is being blotchy, is taking forever to render, might be using the wrong settings but here goes nothing!

It's a shame about all the circles that are appearing everywhere, will look for a solution on that, but either way is closer to what i was aiming for.

Thanks guys!

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# 12 19-12-2012 , 02:58 AM

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Looks good. To speed it up, try the following:

In final gather, turn down the accuracy to around 50. Turn down the point density (Eg 0.5), then increase the point interpolation (Eg 20).

Imagination is more important than knowledge.

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Rendering Light Bulb Glow

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