• Apple Motion

  Intersecting layers with alpha produces strange line

  Posted by Jack Everitt on July 17, 2009 at 8:46 am

  Hi,

  I have a problem with Motion when two layers intersect. On layer is totally opaque, and the second layer has transparent areas. The problem occurs in areas when the transparent areas intersect with opaque areas. In those regions I get a dark gray line appearing.

  Check out this image and you will see what I mean.

  https://jack.fxhome.com/MotionLine.jpg

  Note: I get this unwanted line in the exported frame as well.

  Why does motion do this?

  Is there anyway around this?

  Thanks

  My website – https://jackeveritt.com

  Arnie Schlissel replied 17 years, 2 months ago 2 Members · 1 Reply
• 1 Reply

• 

  Arnie Schlissel

  July 17, 2009 at 2:31 pm

  I think that this is a premultiplication error. Open up the media tab, select that clip, then in the inspector, change the premult setting until the line goes away.

  If it doesn’t go away, it’s an aliasing error. In that case, you’ll need to blur the alpha slightly, maybe 1 or 2%.

  Arnie
  Post production is not an afterthought!
  https://www.arniepix.com/

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