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  • Adobe After Effects

    Composition from Moving Shape?

    Posted by Sam Pipes on February 20, 2012 at 3:28 pm

    This seems like it must be possible, but maybe I’m thinking about it the wrong way, or I don’t know what to call what I’m trying to do.

    I have a large PNG sequence that features a small character running around all over the place. For the sake of file size I must crop it down to a size more befitting the character, but I still want to use after effects to make him blend seamlessly with the background he’ll be dropped into.

    To that end, I came up with this plan:

    1. Place the 1024×768 character render onto the 1024×768 background and composite as normal.
    2. Use the motion tracker to place a null object that follows the character around.
    3. Somehow use the null object as the center of a new, smaller composition, in which the character is always centered.
    4. Export the motion tracker’s position data and use it to properly position the character in-game, resulting in a perfectly composited character with a fraction of the file size. Parades and cake all around.

    Number 3 is the one giving me trouble. Has anyone else had to do something like this?

    Thanks in advance,
    Sam Pipes

    Jon Merrifield replied 14 years, 2 months ago 2 Members · 3 Replies
  • 3 Replies

  • Jon Merrifield

    February 21, 2012 at 8:51 pm

    There are probably ten ways to do this. I am just tossing one out due to me current limited time.
    You could copy and paste your null with the tracking data in the new smaller comp. Then parent that null to a new null created in that comp. Use the new null to shrink the scale of the original null so it now matches the new size of your smaller comp. May be helpful if your new comp size has the same aspect of the original.

    Jon Merrifield
    VFX Artist / Supervisor
    PELi Studios, Austin TX

  • Sam Pipes

    February 22, 2012 at 7:30 pm

    I got it working base on your suggestion. I made an appropriately-sized comp, copied the null and its position data over, then made a new null layer. I attached the comp to the old null, the old null to the new null, then rotated the new null 180 degrees, the chraracter’s motion and the motion of the null cancelled each other out, keeping the character centered at all times.

    Thanks a lot!

  • Jon Merrifield

    February 22, 2012 at 7:36 pm

    That’s awesome, I am glad that worked for you.
    cheers,
    -Jon

    Jon Merrifield
    VFX Artist / Supervisor
    PELi Studios, Austin TX

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