Render Speculrity/Highlights only

Introduction to Maya - Modeling Fundamentals Vol 2

This course will look in the fundamentals of modeling in Maya with an emphasis on creating good topology. It's aimed at people that have some modeling experience in Maya but are having trouble with complex objects.

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# 1 16-03-2012 , 01:38 PM

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Hey all Im trying to render out a specularity pass. In the light that I am using I unchecked emit diffuse and the image renders the highlights only as intended but if i check the alpha of the image the model is still there. I only need the highlights is there something that I am doing wrong

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# 2 16-03-2012 , 02:31 PM

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If it's just for one image can't you just go into the alpha channel in comp and manually fill it in black, leaving the colour channel with just the highlights. Do you need the spec hits in the alpha?

Or can't you adjust the matte opacity of the model material in the attribute editor/hypershade?

Last edited by ben hobden; 16-03-2012 at 02:34 PM.

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# 3 16-03-2012 , 03:12 PM

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Its an animation

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# 4 16-03-2012 , 03:35 PM

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also played around with the matte opacity values nothing changed

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# 5 16-03-2012 , 06:26 PM

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Aren't highlight's usually screened onto the comp anyways?

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# 6 16-03-2012 , 08:32 PM

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Yeah. And even it's for a sequence you could black out or switch off the alpha channel in some way. how are you intending to use the spec pass?'

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# 7 17-03-2012 , 12:56 PM

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Using it in a compositing package(AE) wanted to add effects to the specular pass. How do you guys usually render out a specularity pass? I have switched from multiply to screening but it still looks awefull in AE

Last edited by murambi; 17-03-2012 at 01:00 PM.

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# 8 17-03-2012 , 02:07 PM

The Nurb Herd
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i dont use AE, but the math you use is "plus" i thought.

if i rebuild a primary i plus everything except the alpha.

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# 9 17-03-2012 , 02:41 PM

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Yeah. I don't really use ae but in ps I would screen or linear dodge it. I don't really render out spec passes from Maya, but it's something I mean to do more of, which is why I was interested in this thread. Any screenshots from your results? Have you tried adding any slight tint of colour or blur to the spec to try and make it look a little better?

I have rendered out key light passes before using display layers. Just rendering the scene from a single key light and screening / plussing that over the top, which can be interesting.

Last edited by ben hobden; 17-03-2012 at 02:46 PM.

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# 10 17-03-2012 , 03:06 PM

The Nurb Herd
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yeah if i do a lighting slap comp i render multi diffuse and multi specular passes.
so say i have 3 lights (1, 2 and 3)
i render the diffuse from light 1, 2 and 3 and the spec from light 1, 2 and 3. I also render a primary (rgba beauty). copy the alpha from the primary to all the multi passes, unpremult and use a merge (plus minus alpha) and plus them all together then premult. this way i can use exposure, multiply and grade on each light and relate it back to maya to make changes.

edit: how do you make a gif?

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# 11 17-03-2012 , 04:04 PM

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What do you mean, a gif in PS? An animated gif? Easiest way for me is "save for web and devices" then you can change everything you need like size, transparency and matte color etc.