Electronic Design

Bokode Barcodes Use Angular Dimension To Encode Information

MIT Media Lab has discovered a new use for barcodes by shrinking their size and enabling them to encode information in the angular dimension. This could be useful in shops, the classroom, business meetings, videogames, and motion-capture systems. Named Bokode, the system adds a fourth approach to the options for communicating optical data, which include two-dimensional ordinary imaging, time dimension temporal variations, and light wavelength variations.

Using the angular dimension, emanating rays of light have different degrees of brightness that vary with the angle where they merge. Ramesh Raskar, Media Lab Associate Professor, states that “almost no one seems to have used” the angular dimension for information encoding. “There have been three ways to encode information optically, and now we have a new one,” he says.

In August, the concept will appear in New Orleans at SIGGRAPH, an international conference and exhibition on computer graphics and interactive techniques. Out of over 400 papers submitted, it is one of six highlights of the conference.

The 3-mm wide labels are roughly the size of an at (@) symbol, yet they can hold thousands of bits of data (see the figure). A lens and LED light source are currently required, but researchers hope to make them reflective in the future to reduce costs and make them less noticeable.

“We’re trying to make it nearly invisible, but at the same time easy to read with a standard camera, even a mobile phone camera,” says Ankit Mohan, a Media Lab postdoc and lead author of the paper.

The new labels are designed to be read easily from a distance, as far as several meters, and can be read by digital cameras instead of laser scanners. The name is derived from the Japanese photography term bokeh, which describes the round blob that appears in an out-of-focus image of a light source. The new system actually uses an out-of-focus camera to note the encoded information, as it comes out of the blurred spot. The tag can also be read by the naked eye when the person is less than an inch away.

The MIT research group hopes these tags will replace existing barcodes, since they can hold much more information and are readable to the naked eye, and multiple tags can be scanned simultaneously for easier product comparison. With potential use in the classroom and business meetings, the tags could be put in a keychain device, scanned by a camera, and used for coinciding interaction on a screen.

In motion-capture systems, utilized in the creation of videogames and movies, the position and angle of the tag could be determined by the camera with the Bokode system, which has an accuracy of a tenth of a degree, says MIT. Raskar added that the system “could enable a whole new range of applications.” Some ideas include use in museums with background information and with restaurants, which could advertise their menus on the sidewalk, at least to those with a cell phone camera.

Tags could also replace RFID systems, specifically in near-field communication applications. Currently utilized in some ID cards, RFIDs offer much information accessible from a distance, even when the card is not in plain sight. Unsuitable for credit cards, the Bokode hopes to fix this problem by encoding the same data but requiring the card to be in view as a safety precaution.

At $5 per prototype, the current high cost covers an off-the-shelf convex glass lens, but the price could decrease to 5 cents once production begins. Nokia, Samsung, and the Alfred P. Sloan Foundation sponsored grants for the research, and the SIGGRAPH paper entitled “Bokode: Imperceptible Visual Tags for Camera-based Interaction from a Distance” will be accessible online as of July 27 on the conference Web site.

MIT Media Lab

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