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J
jamesf88455360
Participant
November 11, 2016
Question

Track matte alpha matte problem

  • November 11, 2016
  • 2 replies
  • 1953 views

I have a line and a square and a invisible box. The line is on the bottom and is keyframed to move from the top to the bottom of the screen. I parented the invis box to the line and placed it above the line. Then i alpha matted the box to the invis box (so the box can only be seen when the invis box is above it). According to youtube videos it should work so the box can only be seen when the invis box is above it, but when i do this, the non invis box cannot be seen any more even when the matte invis box is above it. So in other words my track matte is making its matted object invisible even when its above it.

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2 replies

Dave_LaRonde
Dave_LaRonde
Inspiring
November 11, 2016

I'll guess you're brand-new to AE.  Beware of YouTube tutorials!  A lot of them really suck!  Go here:

After Effects tutorials

Learn AE from the Pros and not some lame high school kid who just thinks he knows what he's doing.

J
jamesf88455360Author
Participant
November 12, 2016

Yes what I was asking at the time was why wasn't my invisible box working as a matte layer. I worked it out though and it was because it was invisible, it has no stroke or fill, so there was no matte. When I watched the tutorial a guy clicked the alpha matte and it was invisible so I thought it was invisible to begin with. There's where I got stuck. Any way thank you for your help.

Roei Tzoref
Roei Tzoref
Legend
November 11, 2016

I am not sure about your setup. a screenshot would be better. you should educate yourself through the tutorials from professional authors - there are a good number of those in the adobe website. such as this:

Luma and Alpha modes in track mattes | Adobe After Effects CC tutorials

you can also read about it here:

https://helpx.adobe.com/after-effects/using/alpha-channels-masks-mattes.html

the basic idea is to control transparency of a layer through another layer i.e one layer control the transparency, and the other controls the movement. a good example is to making a peekaboo. a layer beneath reveals itself through a window. that window is the alpha matte on top of it.

so the below layer is the peekaboo element that moves from point A to point B. the window is a solid with a mask or a rectangle shape layer and it is placed above the peekaboo layer. now set the peekaboo element to alpha matte the layer above. now the layer above is its alpha matte and automatically the video switch will be turned off. you can now move the peekaboo layer and it will be visible only in the area that's opaque in the layer above it.

    J
    jamesf88455360Author
    Participant
    November 12, 2016

    Yes what I was asking at the time was why wasn't my invisible box working as a matte layer. I worked it out though and it was because it was invisible, it has no stroke or fill, so there was no matte. When I watched the tutorial a guy clicked the alpha matte and it was invisible so I thought it was invisible to begin with. There's where I got stuck. Any way thank you for your help.

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