[Dale Paquette] " Here's where I get lost. Where do I add the expression? I'm thinking the null's position (because the anchor is different for a null than a regular layer). Also, it's not clear if I'm to copy your expression verbatim or if the references to pick-whips means to actually pick-whip. Finally, since each tracker is on a different layer, both have the same number whereas you have different numbers."
You should take a step back and analyse what you're doing. I think this will allow you to understand things better.
Firstly, each of your trackers provides an Attach Point as a result of the tracking. Your job is to average the values of the Attach Points.
It doesn't matter where the values are, be they in theire original Attach Point parameters, a Null Layer's Anchor Point or Position or Expresion COntrol Sliders. Whether you have $100 in your left or right pocket is immaterial. The fact is you have that $100.
The same holds for your Attach Point values. Where you place them via an Expression pickwhip is inconsequential as their values are absolute values. So to your lastg para, yeah, they are the same thing.
I suggest that you take a look at JJ Gifford's excellent introduction to Expression -
http://jjgifford.com/expressions/basics/index.html
You will do well if you work your way to the Vector Math section.
Cheers
RoRK
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