Adding alpha channel

#1

Hi guys, I’m quite new in after effects…I rendered 2 images sequences from Maya; I need to use the first images sequence as rgb, while the second one as alpha information for the first sequence: both sequences are obviously rendered without alpha.
After I imported both in AE, I used the Set Channels effect and I set Source Layer 4 to my “alpha image sequence”: my probem is that nothing seems to change and if I render everything out…but sequence has still no alpha; should I use another way to set my alpha or I’m doing something wrong using the Set Channels effect?

thanks in advance for any help :wink:

#2

What are you trying to use from the 2nd sequence as your alpha? Is it a black and white sequence? If it’s b&w you could use it as a luma track matte.

If you’re trying to use one of the RGB channels in the “Layer 4” area of the Set Channels plug-in you need to set the “Set Alpha to Source 4’s” drop down to something.

From there you could use your 2nd sequence as an alpha track matte.

#3

yes, the second sequence is a black and white rgb sequence and I selected it in the drop down menu but nothing changes in my alpha channel that is still solid white…

#4

Check your render settings. Enable RGB+Alpha and also of course chose a suitable format that supports alpha…

Mylenium

#5

Yes, I saved it as Tiff image sequence including alpha, but the final result is a white solid alpha channel…

#6

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