Best marker for detection & cam matrix calculation

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Hi, I have a following problem that could use community wisdom.

I need to design a real word pattern/image that i can put on the floor or stick to wall, that has following features:

• can easily be detected by opencv, even if highly warped
• I should easily calculate camera matrix from it
• must hold small amount of data (like a number from 0-2^16)
• there will be many such markers in one image (with different data coded in them)

I was thinking QR codes but they are kinda hard to detect, maybe some combination of chessboard and QR inside?

Maybe QR will be ok for that? Which algorithm you suggest then? (Remember it has to deal with multiple qr on the same image and get the camera matrix from it)