Pose estimation of QR code?

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Hello,

I want to find the distance between my camera(Single/ monocular camera) and the QR Code.

There is an OpenCV function to find the distance between camera and object, for that we need 3D object points and corresponding 2D image point.

How can i find the vertices of QR code in world space(3D points) and image space(2D points) for find the distance between them? and how can we relate the size of QR code to find the pose?

Please anyone can suggest me.