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View Full Version : generate alpha ? (newbie)

nirishere
06-01-2008, 07:05 PM
Hi there guys !
I want to know if there is anything in AE (say even a solid), that I can use to make a hole in my comp i.e. alpha ?

for example there's a man talking in there, and there's a rectangle layer on top of him that makes hsi lower body disappear ?

thanks
superblack
06-01-2008, 10:38 PM
Put a solid above your layer, and set your layers blending mode to "Alpha Inverted Matte".

Sascha
scrimski
06-01-2008, 11:28 PM
Draw a rectangle mask on the layer and set it to 'substract'
nirishere
06-02-2008, 07:55 AM
I understand.
But don't these apply to only one single layer ? what about those that come underneath ?
scrimski
06-02-2008, 09:46 AM
what about those that come underneath ?
Precompose 'em.
nirishere
06-03-2008, 12:10 AM
Cool thanks.
nirishere
06-03-2008, 12:49 AM
Hi there,
I need to make footsteps of a group of people (35, actually as if there were ghosts walking on the surface, leaving traces) walking on a 3D terrain (elevated from a displacement map). there is a camera hovering above the surface (path constraint'd).

What I thought to do was create an animation of the steps on the disp. map...
only problem was that there is quite a big distance of walking (and therefore lots of footsteps).

Now all I need to do is somehow create an footage that places more and more footsteps (that should be aligned to the path), and that will show up on the white background as black (fading from gray into black).

Any ideas ?
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06-03-2008, 12:49 AM
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