-
Motion Tracking Jitters and instability.
I am having difficuties with jitter in my motion tracks after they are applied to the object. some of the footage I am tracking moves a bit fast and that seems to be where I run into problems, but not always since some shots are in slow motion and smooth.
The footage is interlaced and I try to track with the fields, but that still doesn’t work.
I tried expanding the motion target, doing a few of the shots myself frame by frame, using the smoother (which does not work because it is taking all the middle key frames away when I apply it).
One of the shots that I am having the most difficutly with is a shot of a van that is passing by, the shot is in slow motion, and I created a peace sign on the side of the van using the paint tool. I had to do the movement tracking myself because I had nothing to target the tracker on to and the van leaves frame which stops the tracker.
The manual track that I did works well until just at the end of the shot and then the peace sign wiggles and I can’t get it right. The van seems to be moving smoothly across frame, but no matter what I do, the peace sign wiggles at the end.
Also, I don’t quite how to apply a motion track to the paint effect. I tried the whip but, it doesn’ work, so the only thing I can think of is to make a pre-comp of the peace sign effect and do it that way. Any help here would be apppreciated
I just need to find out if there is anything else I can try that can solve this wiggle and jitter problem?
Thanks,
Scott -
3 Replies
-
To smooth out the instability/jitters in a track (or stabilize), a good trick is to use multiple trackers and average their results to obtain your final track. The standard one I use all the time is to track the footage in the forward direction, then make a new tracker and track the footage in reverse with it (tracking the same point I did in the first track, …when combined this should eliminate most small jitters), …then apply an expression to a null layer to average the two tracks to derive its position data, …then you parent whatever object is you wish to lock to that track. Do a search of past posts from this forum to find expressions which do this.
Goodluck!
Andrew
-
I’ve found that After Effects standard issue tracker does a horrible job at small motion. You can have footage with the best contrast, zero noise and motion blur and your track will still produce jitter with small (sub-pixel) motion. Andrew’s method will probably help but if you are using CS4, it’s a much better idea to use the bundled Mocha tracker instead.
-
Here is a link to a page containing the expression text for averaging the tracking data, as applied to multiple null layers. You apply each set of tracking data to an individual null layer, then create a final null layer with the expression to average all of the position data from each of the prior null layers.
https://iaian7.com/aftereffects/NullAveraging
Reply to this Discussion! Login or Sign Up