Tag system with low-powered tag and depth sensing camera

A tag system is proposed that offers a practical approach to ubiquitous computing. It provides small and low-power tags that are easy to distribute; does not need a special device to read the tags (in the future), thus enabling their use anytime, anywhere; and has a wide reading range in angle and distance that extends the design space of tag-based applications. The tag consists of a kind of liquid crystal (LC) and a retroreflector, and it sends its ID by switching the LC. A depth sensing camera that emits infrared (IR) is used as the tag reader; we assume that it will be part of the user's everyday devices, such as a smartphone. Experiments were conducted to confirm its potential, and a regular IR camera was also tested for comparison. The results show that the tag system has a wide readable range in terms of both distance (up to 8m) and viewing angle offset. Several applications were also developed to explore the design space. Finally, limitations of the current setup and possible improvements are discussed.