Before working on Wonderbook, I worked on EyePet. An augmented reality virtual Pet game for PlayStation 3.
The game was shipped with a “Magic Card” which was used to move objects in the game work around in 3D. This was before the PS Move controller was developed. The Magic card uses the fiducial marker system which was later used in Wonderbook. Since this was not tolerant to occlusion, the card had to be physical designed so it was always held without the players hands covering the marker.