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Activity Forums Adobe After Effects Alpha Track MAtte Problem – a weird border appears!

  • Alpha Track MAtte Problem – a weird border appears!

    Posted by Florian Liedtke on November 15, 2018 at 2:07 am

    Hello guys and gals,

    First, sorry if that is a duplicate post, but I was not able to find anything on the net, I might not have the right keywords. If there already is a post with a solution, I would be really happy if you can send me a link!

    So the problem is this:
    I am sitting here with my students and I show them the track mattes. We are creating a face that blinks, very simple.
    So the eyelids are tracked by an alpha track matte, and we created it like I always do: Duplicate the eyeball layer, put it on top of the eyelid layer, and set the eyelid layer to alpha track matte. We also used this technique for the teeth inside of the mouth.

    We all get a thin border around the result, just like a line of 1px is missing/not being erased.
    This really baffles me. I am experienced in AE, but never encountered it before (or I just did not notice it).

    For your info, the graphics are created in Illustrator, the AI file imported as a composition, and the collapse transformations/continously rasterize “sun” is activated. The eyelid-layer is a solid created in AE.

    You can best see it in the mouth, thats why I upload this picture. (its zoomed in quite a lot, thats why its this pixely)

    There should be no black line where the white teeth hit the border of the mouth, but its there. Its the same for the eyelids.

    CAn you tell me why this is happening, and maybe also give a solution?

    Thanks and best greetings from China,
    Flo

    motionkontor.de

    Kalleheikki Kannisto replied 7 years, 6 months ago 2 Members · 2 Replies
  • 2 Replies
  • Kalleheikki Kannisto

    November 15, 2018 at 2:20 pm

    Answered a couple of days ago here:

    https://forums.creativecow.net/thread/2/1133182

    Kalleheikki Kannisto
    Senior Graphic Designer

  • Kalleheikki Kannisto

    November 15, 2018 at 2:28 pm

    You can use a different solution in your case: Precomp the mouth interior color with the teeth with extra area extending beyond the final mouth area and then use a track matte to clip both the interior and the teeth in one go.

    Kalleheikki Kannisto
    Senior Graphic Designer

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