Alpha Channel for Fire & Smoke passes

[AlexC]

Hi,

When I render seperate Smoke and Fire passes in 3dsMax 2011 64bit, the alpha channel is the same for both passes!? Is this correct?

If I disable Smoke and render Fire only (and vice versa), I get the correct alpha in the passes which allows more freedom in the comp.

I am confused as to why there is an option to render the elements if the alpha is the same.

Am I a missing a trick here in the comp stage or should the alpha's be different when rendering both smoke and fire together and saving the different elements?

I have searched as much as possible, and have not found an answer here, so apologies if a post exists.

Thanks
AlexC

[sitnisati]

Hello,

Did you try to put one RE on top of another and use multiply filter in Photoshop ?
That should work fine.

Kresimir

[Jordan]

I have ended up turning the alpha spinner in the Fire follout in the Rend tab of FumeFX to 0 the you get a nice alpha for the smoke and then plus the fire over the smoke.
Though it would be good to get different alphas for fire and smoke.

[AlexC]

Thanks for the replies,

I have tried both methods, but still not exactly what I am after. I want the freedom in the Comp (using Nuke), to alter both completely seperately, using the alphas as masks. To me this seems to give the most freedom.

Can I add it to the wishlist for the next update please?

[sitnisati]

It would be hard to tweak just fire or smoke alpha in post as those two channels are usually completely mixed during rendering on the camera axis.
It's like you have 4 layers of smoke, then 6 layers of fire, 2 layers of smoke, etc.
So, if you'd have just opacity of fire that does not include smoke at all, how you can blend it in ?

Kresimir