CGTalk - alphas and spectral clouds

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lotusexige

01-27-2007, 06:50 AM

hi all
I can't seem to pull an alpha matte on my scenes with cloud fomations. I want to generate some nice clouds in vue6 and comp them into a live action plate - but they seem to be ignored by the alpha chanel.

Am I doing something wrong? I tried putting an alpha plane behind the clouds, but that made no difference it only masked out the sky - not the cloud.

is this a 'feature' I wonder ?

bruno021

01-28-2007, 06:03 PM

If you use volumetric layers, you can't separate them for the sky, they're part of it, so you need to use metacloud objects.

Farsheed

01-30-2007, 03:03 PM

I tried Using metaclouds.. I still don't get an alpha .. of just the cloud ..

lotusexige

01-30-2007, 03:59 PM

Exactly - no matter how much I play with it, i just can't get a mask of my metaclouds/spectralclouds

Doing multi-pass/g-buffer doesn't matter either. load up the layered PSD file and no mask data for the cloud, only planes like ground and water etc.

Khalor

01-31-2007, 07:22 AM

Maybe MetaClouds against the 'Mask' atmosphere (I forget what it's called - the plain black one), and a 'screen' transfer mode or similar onto your footage might do the trick?

Farsheed

01-31-2007, 12:52 PM

meta coulds don't work with the mask atmospheres .. they only work with the spectral atmospheres.

Grrr.. . . that's lame .. how can they not have alpha setup in a 3D porgram .. !! ..

skin12002

01-31-2007, 09:17 PM

Hi

How about creating a huge black plane behind the clouds and using that as your alpha

Skin

piper1234

02-02-2007, 11:31 PM

or greenscreen inside vue :shrug: and later compositing it

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