I love working with alpha / luma mattes in After Effects.

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Creating that kind of composition should be a piece of cake, but it is incredibly difficult because there is no real good way to work with mattes in After Effects (CS6 here); while it's one of the most important feature in a compositing software.

I would be glad to know how you work with them and what workarounds you know.

Track mattes

Track mattes is the best way to work with mattes; but what if you need to use the same matte on several layers ?

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You end up duplicating your matte, which multiplies the number of layers in your composition, and is a good way to bring problems since you have to keep your layers "synced" : if you have animation keys on a layer matte, you'll need to copy/paste them on the cloned layer every time you change something, unless you parent them or use complex expressions to do the job for you, which bring other problems.

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Set Matte plugins

The Set Matte (native) plugin is really cool about this; since it allows you to use a unique layer as matte anywhere in your comp.

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There is also the bs-Smart Set Matte plugin (from BS_CompositingBundle 2), which has some advanced options: you'll be able to stack several mattes and to choose how they are composited, which is really, really nice; and to select the mode to use for the matte (alpha, luminance, lightness, etc); among other options, but you'll have to pay for it (~30$).

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But the problems with both plugins are that :

  • If the matte / matted layer geometry (scale, position, etc) differs or are animated, the plugins will fail to keep them "synced" and you'll get weird offsets. You could eventually parent them, but that brings other problems (what if I want to rotate my matte layer ? The matted layer will rotate too :/ )

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  • If you copy a layer which has a set matte effect on it, the Take Matte From Layer value is lost when pasting the layer, which is really annoying since you'll quickly won't remember where which layer is used as matte.
  • If you use a layer (matte) that already have a set matte effect on it AS matte for another layer (matted); matted will be matted with matte WITHOUT considering the set matte effects applyed on matte.
  • bs-Smart Set Matte responds poorly when applyed on text layers.

Well, my head hurts.

I'm sure I'm not the only person facing those problems.

What I would dream of is a set matte effect which would have advanced options as bs-Smart Set Matte has, and above all an ignore transformations option, avoiding the offsets issue described above.

Any hints ?

  • I don't have any help to offer, but I just wanted to say thank you for posting this question. This is exactly the sort of question that belongs here and gets the site out of just being the ffmpeg support forum. Nov 19, 2016 at 0:49
  • You know about Stencil / Silhouette Alpha mode, right? That applies the matte to all the layers below it. Also, keeping animated properties in synch is super easy with expressions. Just alt-click the stopwatch and drag the expressions pick-whip (like the parenting pick-whip) to the property you want to synch to and you're done. Too easy!
    – stib
    Nov 22, 2016 at 5:44
  • Sure stib. But it forces you to do a lot of precomps as all the layers (eg. a background) below will be hidden, which is not handy. It would be great if you could use "folders" in the timeline, as Flash does... :/
    – gordie
    Dec 10, 2016 at 17:44
  • @gordie If folders on the timeline were a feature, it would make this incredibly easy. Imagine being able to Stencil Alpha inside of a folder and only affect a select number of layers, ignoring the ones below the folder. A person can dream :) Apr 12, 2017 at 22:38


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