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Macha

Smoke alpha

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I have 2 renders: A pyro explosion and a light in a volume with some shadows.

I composite both of them to get a nice bang but the prob is I have no proper alpha for the light. The pyro effect has the Asmoke and Afire export parameters, so that's good but my light only gives me the alpha of the volume it sits in (a sphere).

What's the best way to get a good alpha channel out of this? I tried using luminance, etc but...meh... doesn't look good.

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Rather than using an Over, try using a simple add or screen (if 8b). This will make the light rays less shadowy looking.

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That's right, but then it looks too bright. Tricky tricky.

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In that case, go back to the over and use a gamma and/or bright COP to adjust only the alpha matte of the explosion until you get the look that you want. You'll probably want to reduce the gamma to 0.7 or something to have the matte falloff more quickly, which would increase the contribution of the background image under the rays.

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