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Alpha Channel Export Problem!

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Guido AgüeroAlpha Channel Export Problem!
by on Aug 21, 2011 at 6:33:37 pm

Hello Folks!

I am having a problem trying to export an animation with alpha channel!

The animation ends with a cam's lens where the lens is going to be the final Scene, where the AE cam is going to fly and then make a transition to other scene!

I am using a Black circle and the blend mode of it is set to "silhouette alpha" so I can have alpha channel in that area(The circle one).

The thing is that I can see the alpha in the composition but as I export it what I get is a black circle and it is suppose that i should have the alpha channel in the export!

I know that I should select the RGB+Alpha in the render settings menu but AE doesn't give me alpha!

So my question would be: Am I doing something wrong? or Is there any other way to do it?

Or I really do not remember well. but i guess someday I downloaded a plugin or script that can do it!

As i said, I know there is some preset that allows you to convert that "fake" alpha to real alpha when you export it but i forgot the name of the plug in and also it's creator.

I hope you can help me with this issue! and also understand my bad english.

Thanks in advance!


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Stefan HinzeRe: Alpha Channel Export Problem!
by on Aug 21, 2011 at 6:40:34 pm

hey,

and you are shure there is no alpha in the final render?
did you reimported the video back in AE and checked it?

i am thinking, maybe the edit-software just can´t read the alpha..

greetz

(take a step back, to see the bigger picture)


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Guido AgüeroRe: Alpha Channel Export Problem!
by on Aug 21, 2011 at 6:59:30 pm

Hey Stefan! Thanks for the reply!

Yes, I have re imported the render to AE but it does not have Alpha! AE does not ask me about alpha.

Where it is suppose to have alpha, AE Renders on Black.

So still looking for some help!

Thanks a lot!


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Stefan HinzeRe: Alpha Channel Export Problem!
by on Aug 21, 2011 at 7:04:04 pm

hey,
go to the projekt-window, right-click the reimported video, interpret footage, look at the alhpa settings, play with them...

hope that helps
(becouse i am german i´m not shure about the translation... just in case you are wondering..)


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Guido AgüeroRe: Alpha Channel Export Problem!
by on Aug 21, 2011 at 7:18:08 pm

Mmm That's right I already check those out!

Alpha settings are grey out!


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Tudor "Ted" JelescuRe: Alpha Channel Export Problem!
by on Aug 21, 2011 at 7:42:43 pm

When you say "AEW dosn't give me alpha" it makes me think that you are rendering to a codec that does not support alpha... so, what codec are you rendering to?

Tudor "Ted" Jelescu
Senior VFX Artist


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Guido AgüeroRe: Alpha Channel Export Problem!
by on Aug 21, 2011 at 8:08:21 pm

Yeah the codec i am selecting is "Animation"!

But when renders it gave me a black solid color instead "Alpha channel"!


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Tudor "Ted" JelescuRe: Alpha Channel Export Problem!
by on Aug 21, 2011 at 8:53:31 pm

That's weird! I just tried a simple test replicating your comp and it renders just fine... Are you sure that you do not have a layer at the bottom - black solid? In the Comp window, if you select the alpha view only do you see the black and white image of the alpha?

Tudor "Ted" Jelescu
Senior VFX Artist


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Guido AgüeroRe: Alpha Channel Export Problem!
by on Aug 21, 2011 at 9:21:24 pm

There is not black solid in there!

Maybe i am not explaining it well.

I have on top of all layers a black circle, with it's scaled from 0 to 100, that's is going to be a transition to go to other scene. Right?

There are like 20 different layers behind it and i have set that black circle as "Silhouette alpha" in the blend modes(because is the only mode that shows the alpha channel in the black circle area).

Yeah and also the alpha view bottom is enabled.

It is weird because I see the alpha in the comp but as soon as I export it doesn't.

I have tested it with different codecs just to try, and using TGA image sequences in 32bit worked as I wanted but in this case i do not need image sequence i need video.


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Tudor "Ted" JelescuRe: Alpha Channel Export Problem!
by on Aug 21, 2011 at 9:48:47 pm

Instead of doing it this way, you can precompose all your layers, except the Circle layer that is animated and then animate a mask on the precomp. This way you are just cutting a mask and that should work with no problems.
On the other hand, if you already have a TGA sequence with alpha, why not bring that sequence in AE and render out an Animation .mov with alpha?

Tudor "Ted" Jelescu
Senior VFX Artist


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Guido AgüeroRe: Alpha Channel Export Problem!
by on Aug 21, 2011 at 11:14:00 pm

You are right Ted!

I precompose the comp and it works but i really did not wanted to do it! I thought there was a way to do it with out pre-composite it.

thnks anyways for helping me!!!


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