Checkerboard

Calibration target for camera intrinsics & extrinsics. Calibrate the screen once, then the squares are physically correct in millimetres.

1 · Screen calibration

Drag until the white box is exactly the size of a bank card (or any ID-1 card)

2 · Pattern

Inner corners across

Inner corners down

Square size (mm)

Origin marker

3 · This display

Studio wants inner corners, not squares — the drawn board is one square larger in each direction. The origin marker identifies which physical corner the detector called (0,0); without it a symmetric board has four equally valid labellings and the extrinsic solve refuses to guess.