2 Replies Latest reply on Mar 3, 2011 2:03 PM by Dave LaRonde

    Advice : Tracking multiple times in one clip

    Lee Faulkner Level 1



      Having a few workflow issues getting this to work for me...


      I have a 1 minute clip ... its a bunch of people dancing around in front of a fireplace circa 1800's (ie in period costume). The shot is handheld and pans around a bit.  The crew left a very visible camera lens on the mantlepiece above the fireplace! I am trying to hide it by placing a framed drawing  in front of it (a tiff still image)


      I figured I'd create tracking data from the background (dancing) and apply it to the  picture in the foreground which would be scaled and rotated to fit over the Lens. This I can do. However the dancers frequently pass over the inserted picture so I'll need to cut moving masks around them as they pass in front of the foreground picture.  Laborious, but I can do that too.


      My problem comes because the dancers also pass over tracking points. In addition tracking points also move out of frame, so I need to motion track in sections.


      This is what I've done:


      I import Dancers and Picture ... set the playhead at the beginning of the clip, I scale the picture, rotate it and place it correctly over the errant lens.


      I open the Tracking window,  set the Background as the source, and the picture as the Destination, select two points on the background, I start at the beginning of the clip with the 2 good tracking points (position and rotation) and let AE track forward it works until it loses the one or both of the track points. I apply the data. This makes the Picture hold still until the track runs out of good data.


      What now?


      I've tried adding a second tracker just before the first goes bad (trying 'cut' from one set of tracking data to the next) ... but the result of the second track is a picture way out of position. I've tried deleting the 'bad' keyframes at the end of the first track , but just can't get a clean transition to the second tracking data. I've split the clip  and tried tracking each segment separately,but for the life of me I can't get the picture to stay in place seamlessly between splits ...


      Can anybody suggest a better workflow please?  ( if you can understand my rambling!! ;-)  )


      Thanks in advance