We present our new interaction technique for tabletop system and video game application using it. This technique is for recognizing a pinching gesture performed with the thumb and forefinger and tapping gestures with them by a ceiling camera above the table. The positions and orientations of multiple gestures are recognized at 200Hz, and the users around the table are tracked by their arm positions. This technique is useful for large-sized tabletop system for multiple users because it does not require any additional equipments to them nor registration process before using the system. Some pilot studies demonstrated the robustness and accuracy of the proposed technique with displaying appropriate guide on the display. We also developed a video game application called "Pac-pac". A player can shoot a bullet along the orientation of his hand by tapping, from any side of the table. We exhibited Pac-pac several time and well-received.
2. Kentaro Fukuchi, Toshiki Sato, Haruko Mamiya, Hideki Koike, An Augmented Tabletop Video Game with Pinching Gesture Recognition, SIGGRAPH ASIA 2008, Emerging Technologies, 2008.