Instant Replay

Real-world, slow-motion instant replay for air hockey. This new space-labeling technology tracks the pucks with a high degree of accuracy and speed (1cm/500 Hz) in natural illumination without visible tags.

Enhanced Life
Instant Replay is an inexpensive, highly accurate "motion capture" system that effectively tracks many fast-moving, rotating objects. The system works at very high frame rates (500 Hz) and reduces cost by employing relatively simple LED projector components instead of high-speed cameras. The cost of the system is only a few hundred dollars.

To demonstrate a new space-labeling projector technology within a fast-paced, engaging, high-impact setting that presents multiple challenges to system throughput and component wear.

The core technical innovation of this work is the system's space-labeling technology. An array of inexpensive, solid-state, high-speed LED devices project 10,000 invisible (infrared) patterns per second into the space. Any number of photo-sensing tags within the space detect these patterns and are thereby able to determine their own locations. Since the entire space is "labeled," the speed of the system remains constant regardless of the number of tags being tracked. The tags use very inexpensive, off-the-shelf IR-decoding modules and micro-controllers. The tags can be detected in natural environments (under natural illumination and imperceptibly embedded on natural surfaces). Traditional motion capture systems require high contrast between tags and background.

The theoretical maximum speed of this system is much higher than our (500 Hz) prototype and is limited only by the speed of optical communication components. This technology could be used in a variety of industrial applications such as tracking crash-test dummies or localizing robots. In the future, space-labeling projectors might be deployed throughout buildings and other space, allowing people (or their electronic devices) to determine their precise location at any time.

Emerging Technologies Sketch

Ramesh Raskar
Mitsubishi Electric Research Laboratories (MERL)
Raskar (at)

John Barnwell
Vlad Branzoi
Erich Bruns
Paul Dietz
Hideaki Nii
Michael Noland
Jay Summet
Jonathan Westhues
Yong Zhao
Mitsubishi Electric Research Laboratories (MERL)

Shree K. Nayar
Columbia University

Masahiko Inami
University of Electro-Communications