I’ve been playing around with putting IR LEDs on the corners of a rectangular plane, and initally thought I could maybe use that to define the corners of a homgraphy node. but this is a bit simplistic and I haven’t got very far because of having problems sorting the blobs. I suspect it’s not the right approcah anyway.
A couple of solutions (not tested):
use 1 led, 2 leds, 3 leds, 4 leds for each corner, use blob size to fetch etch one separately
use colored leds (no IR “transparency” in this case but fancy lights instead) for each corner
track the leds with contour only at the start, and use the bounding boxes of contour to set the roi of a camera shift tracker. in theory it would be track the points (without loosing the id) until they are inside the view of camera