If you want to make it unique, it syould be simple to cover it wit QR codes. If you know the location, size and orientation of each (which can be encoded in the

If you want to make it unique, it syould be simple to cover it wit QR codes. If you know the location, size and orientation of each (which can be encoded in the QR itself), you should be able to calculate the position of the cameea pretty accurately by meassuring the perspective distortion.