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Tuesday, January 06, 2009

Paper Review: Bridging Physical and Virtual Worlds with Electronic Tags

This paper is written by Roy Want, Kenneth P. Fishkin, Anuj Gujar, and Bevely L. Harrison from Xerox PARC that was published in CHI 1999.

This paper is an extension from previous work that attempts to connect physical objects with virtual representations or computational functionality by using RFID (Radio Frequency ID) tags. The problem this paper is trying to solve here is how to leverage strengths and intuitiveness of the physical world to provide users additional ways to interact with applications and information in virtual worlds by following physical objects’ natural affordances. This problem is important because it enriches interfaces that enable the users to interact with information and computational devices naturally. It is important to both interface designers and general users.

The main insight of this paper is that RFID tags should be used instead of bar codes or glyphs, because they allow seamless augmentation with unobtrusive tagging. They are very small (easy to hide), inexpensive, and required no precise alignment and registration. The RFID tags themselves do not need on-board power, last a long time, and can be easily added to physical objects. The authors also pointed out two disadvantages: the administrator will need to associate functionalities to the tags and maintain it; because of the unobtrusiveness, the users might not know what are tagged and with what semantics.

The authors experimented with several prototype applications, such as tagging a French dictionary; so when sensed, it will invoke a language translation program to translate the currently displayed document. Another example is a tagged bookmark that will bind the current page to the tag and use it later to retrieve the page. Other examples include tagged books/documents, business cards, photo cube, and wristwatch. The power of this idea is that a tag can be associated with any semantics such as functionality associated, or context based services.

The evaluations used in this paper are the prototyping applications. Since this paper discusses the general idea of using RFID tags with physical objects, such an evaluation is proficient. For papers that might propose using RFID tags for a very specific problem under specific context (such as using RFID tags for an intelligent walker for eldercare), more extensive evaluation under that context would have been very necessary.

Since we are talking about RFID technology here, I'll extend on this topic some more. The kind of tags discussed in the paper look like the one shown in the image on the right. Another type that is more commonly used with merchandises nowadays look like the picture below that. What makes the technology so attractive is that these tags are passively powered. So the tags themselves do not include batteries. And when we point a RFID reader to the tag, it gets powered by the reader and then send radio signals back. That's why the more powerful the reader (and the antenna length and sensitivity), the longer range we have in sensing. These tags are also super cheap and very durable and can last a long time. These two educational videos below explain what RFID is and how it works.

Currently, the most widely usage of RFID technolgoy is in the manufacturing and retailing industry. The technology enables quick and easy way to identify products. However, they also arouse very severe security and privacy concerns. For example, I have read news articles that thieves equipped with powerful RFID readers could scan semi-trucks at truck stops to identify what kind of goods are transported and were able to successfully identify a truck load of brand new Dell computers, which they stole later. Extending from that, someone could also easily identify what kind of appliances or furniture you have at your home. The following videos demonstrate how hackers could easily start your car or duplicate your passport information when the technology was applied carelessly.

A few years back, one government lab in California (I cannot remember which one now) wanted to require all employees to be implanted with RFID tags for security reasons, because unlike badges, implanted tags cannot be stolen or lost (in fact, this actually makes it less secure because tag IDs can be easily duplicated). This ultimately resulted in a new law being signed into effect by Governor Schwarzenegger making it illegal in California to track employees by implanted RFID chips.

Public detectability and ease for duplicability are the two culprits to be blamed. However, what I want to point out is the RFID technology can still be applied to many areas as long as we go through careful design. And also the usefulness and feasibility really depend on the context. Like for example, with the French Dictionary example shown in the paper, security and privacy are not really the concerns, and RFID tagging can indeed be used creatively and with lots of fun.

Don't wait till the last day to submit your conference paper. The power supply of your computer might die and you might not be able to get to your files in time.