This sounds like you want to use parenting. It is hard to tell because we can't see your timeline and the modified properties of the layers.
If I understand things correctly:
- Tracked the nose of the character
- Applied tracking info to the null
- For clarity we name the null "nose track"
- Character rigged with nulls
- The important null is the one attached to the hand
- For clarity let us name the null "hand null"
The problem: Attach the Hand null to the nose null but with an offset.
- Add a new null to the Character Comp and name it "nose tracker null"
- Drag the Parent comp timeline above the Character comp timeline so you can see both timelines
- Select the new 'most tracker null' in the timeline and press the p key to reveal the position property
- Select the 'nose track' null in the Parent comp and press the p key to reveal the position property
- Alt/Option click on the stopwatch for position for the "nose tracker null' in the Character Comp to start an expression
- Drag the expression pickwhip from the 'nose tracker null' in the Character Comp to the position property of the 'nose track' null in the Parent comp and release
- The expression should now read: comp("Parent").layer("nose track").transform.position
- Parent the hand null to the nose tracker null
You should be done.
Thanks a lot Rick, but that doesnt work unfortunately, that was my first attempt aswell of course.
The "Parent comp" and the "Character comp" are different size, plus the "Character comp" is scaled to 30% and linked to a Null having tracking data,
i have at some point to use expressions like toComp or toWorld i guess, but a simple parenting doesnt work in that case.
Any other idea ?
Thanks in advance,
Having your comps at different scales would make this fairly complicated. It might be faster/easier to just open up a second comp viewer so you can see your main comp and just animate the hand instead of trying to attach it to a tracking point or something.