2 Replies Latest reply on Mar 26, 2013 12:35 PM by Rick Gerard

    track mattes in after effects




      I'm looking to create a mask so that I am able to insert mutiple screenshots into a specific framework.  I would like to be able to resize and reposition each screenshot while keeping them inside this framework.  I believe the best way to achieve this is to draw a mask on a solid layer, and then have my screenshot use the alpha channel of the solid layer.  Is this the correct way to go about achieving this effect?


      I run into trouble when I enter my second screenshot under that same mask layer (or if I duplicate the screenshot layer), as the mask no longer effects the screenshot layer and it reverts back to its original image size.  My workaround is currently drawing a new mask for each screenshot that I bring in, but that just seems tedious.  Is there a better way to do this? Am I not understanding the concept of track mattes?  Feedback appreciated, thank you.

        • 1. Re: track mattes in after effects
          Dave LaRonde Level 6

          You're in luck:  this is easy stuff.


          If the track mattes are rectangular, you can use the same solid over and over again by duplicating it.  Once you have your footage positioned properly, just parent the track matte to the footage layer, and you can move/scale/rotate the footage layer as you wish.


          If you've created a mask on a solid -- let's say it's curvy with some sharp points, for example -- again, just duplicate the layer and use it as a track matte.  Use the same parenting trick on them, too.


          Nothin' to it.

          1 person found this helpful
          • 2. Re: track mattes in after effects
            Rick Gerard Adobe Community Professional & MVP

            You can do this several ways.

            1. Put your grid mask on the bottom layer and enable preserve underlying transparency. It's the little T between mode and track matte. This will make everything clip to the alpha channel of the underlying layer.
            2. Put your grid mask on the top layer and select a blend mode of Silhouette Alpha or it's inverse, Stencil Alpha
            3. Pre-compose all of the layers you want to mask and then use your grid mask as a track matte.
            4. Pur your grid mask anywhere, turn off visibility, and apply Set Matte to each layer you want to mask. Pick the grid mask layer as the matte source.

            I could go on and on. There are at least 4 more that come to mind. Without knowing more about your project I can't say which would be the easiest.

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