• Adobe After Effects Expressions

  interpolating a 3D camera track onto 2’s

  Posted by Rural_idyll on August 19, 2007 at 1:59 pm

  i’m comping a 3D camera pass from studio max with a character pass moving through it on singles, at 29.97fps.
  i’ve posterized the character animation onto 14.985fps to get a more stopframe feel, but am keeping the camera move on 1’s to avoid a clunky track.
  i’m now manually repositioning the character pass on every even frame to keep him moving with the track.
  has anyone any clever expressions or sneaky frame blending tricks to avoid copy and pasting hundreds of frames?
  as its a 30 second spot at NTSC,
  thanks again

  Rural_idyll replied 19 years ago 2 Members · 2 Replies
• 2 Replies

• 

  Filip Vandueren

  August 19, 2007 at 4:43 pm

  so your scenery pass is also 3d footage at 30fps,
  The character uses the same camera move, but it is rendered out at 15 fps…

  Or is the background live footage that was cameratracked ?

  I gather you have exported your camera to After Effects ? What about a Null or light that is at the 3D position of your character ?

  if you have a point in 3D that’s moving at 30fps, it could be possible:

  find out the 2D position on screen of the 3D point, using toComp().

  Find out if we’re on an even frame -> if so, calculate the difference of that point between now and 1 frame ago, and add that difference to the position of your Character pass layer.

  get me some more info, and we’ll figure out the expression.
• 

  Rural_idyll

  August 24, 2007 at 11:05 am

  Thanks a lot for your response to this post.

  we did export the camera info and hitched it onto a null in AFX.
  the main issues have been to do with all the lighting render passes and shadow mattes on singles jarring with the remapped character passes on 2’s.
  luckily the directors have opted for the whole piece, including the camera pass, to now all be on 2’s, so its a much easier solution alround.

  Thanks again nonetheless

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