Using a 2-point track pulled from the text on the original card, I try tracking on some new text. And this the problem; the text never remains properly centred on the card. You can see that on frame 1 it's positioned correctly, but by the end it's shifted vertically:
Setting Match Move to "horizontal only" isn't really a solution, because there *is* a small amount of vertical movement, and that need to be present with the replacement text to sell the shot properly.
Can anyone suggest anything? The anchor point of the text is set to the dead centre of the group. Am I thinking the wrong way with a simple 2-point track? Is there something really obvious that I'm missing?
I seem to have fixed it, but I'm not entirely sure why it's worked!
I applied the Threshold filter to the original card to create a hicon B&W clip, rendered that out and reimported it and did a 3-point track on the text. The fact that it was quite sharp-edged B&W helped the tracker retain a better lock during the frames where the card was moving the most and the text was motion-blurred.
Then I just applied Match Move to the text and played with the sources of the Anchor and Rotation-Scale parameters until I got what I wanted. Turns out that to make it work, Anchor needed to follow Track 3 and Rotation needed to follow Track 1. Any other combinations gave me wrong results.