Mask compositing

[beenyweenies]

Hi, i need help to compositing a scene in AE. I rendered on a layer a character and on an other layer his mask, everything saved in tiff.
Now in AE i want compositing the two layer because i want cahenge the backround with an image, but i don't know how do it.
Can you help me?

Put the render of the mask above the character layer in your timeline. Then, on the character layer, there is a pulldown menu for choosing the matte type - set it to "alpha matte." If you cannot see this pulldown menu, there is a tab at the bottom of the timeline window (in AE 6.5) called switch/matte push that and you should see the matte options. In AE 7 the button to reveal this option is in the lower left corner of the timeline window.

[ciambella]

0k, thank yoou!! i fixed it!

but now i have another question : what do i must to do if i have in the first layer the alpha of the character in the second layer the color of the character then in the third the backround and i need to put another alpha (different from the first) for the character??

[beenyweenies]

0k, thank yoou!! i fixed it!

but now i have another question : what do i must to do if i have in the first layer the alpha of the character in the second layer the color of the character then in the third the backround and i need to put another alpha (different from the first) for the character??

I don't know if I catch your meaning, but I'm assuming you mean that you want to apply a second alpha to your character/ If so, select the character and the first alpha, then press <CTRL><SHIFT> C - this will bring up the "precompose" window. give this new precomp a name and apply your second alpha channel to the precomp.

[ciambella]

you are the best!!:buttrock:

thank you, i fixed everything!!:thumbsup:

[tCREAM36]

quick question.. i have a 3d animation and all the png file masks(alphas) so i wouldgo through each frame a placeing the next mask over the animation to get it cut out, does AE know its a mask and auto cut it or do u like click the layer and click like (i dunno) apply mask?

[scrimski]

Import as a sequence, bothe the animation and it's alpha sequence.
Create a new comp, put both sequences in, the alpha above the footage, choose alpha matte for the matte settings for the footage in the timeline.

If your footage already contains an alpha channel, the choose the approriate option when importing the footage sequence.

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