Abstract. We designed and implemented a vision-based projected tabletop interface for finger interaction. The system offers a simple and quick setup and economic design. The projection onto the tabletop provides more comfortable and direct viewing for users, and more natural, intuitive yet flexible interaction than classical or tangible interfaces. Homography calibration techniques are used to provide geometrically compensated projections on the tabletop. A robust finger tracking algorithm is proposed to enable accurate and efficient interactions using this interface. Two applications have been implemented based on this interface. Key words: Projector-camera systems, projector-based display, interface design, tabletop interface, homography calibration, finger tracking, augmented reality, bare-hand interface.