? Incomplete Tracker Fade In ?

See attached: I am smoothing a shaky camera move using a Tracker Node, and following the "Smoothing Motion" section of the manual. The Manual does not mention one of the parameters AT ALL!! Google returns zero results for
https://www.google.com/search?q=fusion+%22incomplete+tracker+fade+in%22

Grrr!!!

Help?

(And someone update the manual please.)

Interesting. I've never used that mode before, and the control doesn't appear in the Fusion Tool Reference, either. My guess would be that if you have a tracked pattern that doesn't exist for the entire time over which you're tracking, that tracker's contribution is applied gradually from the time it appears until it reaches full strength. That would prevent the track from suddenly jumping when new data becomes available. The value is probably the number of frames over which it happens.

Mathematically, you'd have something like this:

Suppose you have two trackers, A & B. The average value of these two trackers is used to determine a position: (A + B) / 2. A third tracker, C, becomes available. You want it to have no influence when it first appears, but after a certain number of frames, to have equal strength with the other two. We'll use t to represent a normalized (from 0 - 1) value for time elapsed since the new tracker appears.

((A + B) / 2) * (1-t) + ((A + B + C) / 3) * t

That's a guess, though.

Thank you Bryan!
That sounds right.
Update: that google search now returns... one result!