Expression to get an axis position in screen space?

Hey all,

I’m trying to us Ls_Nail to fix some slightly floaty cg. It wants 2 tracker values, which is all well and good except the part I’m trying to nail down moves briefly out of frame. I have solid planar tracks on both the CG and the plate and can just parent an axis to the tracks where I want and it sticks, but am not sure how to convert that back to a 2d tracker. I guess I could put something in there and then track it, but that seems dumb. Plus, I’d still have to jimmy the resulting curve when it goes out of frame.

I want to get a screen space x,y for an axis that’s getting moved by other means (be it planar track, camera track, etc.) Is there a way to do this with expressions? TIA!

Best solve I can think of is to make a surface with 2 x’s on it. Parent it to your planar track and then 2d track the x’s.

The planar tracker tends to have skew which won’t translate to a 2d track.