Tracking Locations of Moving Hand-Held Displays Using Projected Light Jay Summet and Rahul Sukthankar Georgia Institute of Technology,Intel Research Pittsburgh

Motivation “All lights in an environment will eventually be replaced with projectors” –The Office of the Future projectThe Office of the Future project Tracking locations by programmable light –Demo videoDemo video

Localization by Light single pixel light sensor –bright = 1, dark = 0 projectors update screen at 60 Hz –send 60 bits data in 1 second

Packet 1 packet contains 16 bits data –10 bits for location Identify 1024 unique locations of a 32 * 32 grid –6 bits for projector ID identify 64 different projectors Hamming code: detect transmission error & the start of each packet –(log 2 N ) + 1 additional bits –5 bits (31%) overhead –Examine the last 21 bits received and attempt to validate the packet

Tracking the sensor Once the location of a sensor is detected, switch to a tracking mode –A hexagonal tracking pattern around the light sensor can track which direction the sensor move to

Packet in Tracking Mode 1 packet in tracking mode contains 8 bits –3 bits data to identify 7 areas –2 framing bits Use the framing bits from the current packet and those from the following packet to synchronize –3 check bits Tracking slow hand motions – approximately 12.8 cm/s

Contributions Use hamming code to validate packets; do not need additional RF receivers to synchronize with projectors as related works –Self-synchronization –Cost down –Robustness Tracking of sensor while using remainder of the display for output –Flexibility –Independence