Quality Table Time: ShareTable Facilitates Long-Distance Communication

Monday, June 6, 2011


When Svetlana Yarosh came south to Georgia Tech from her hometown in Maryland, it was the first time she’d ever lived more than an hour’s drive from her little brother. She promised to keep in touch. She promised weekly phone calls, long video conversations via Skype. And she delivered on those promises, but something was missing.

“With a phone call, your interaction is limited,” says Yarosh, a Ph.D. candidate in human-centered computing. “Even with Skype, after a while you’re just staring at each other.”

Eager to maintain connection with her brother, Yarosh began visiting long-distance parenting forums on the Web. She found that, other than communications media like telephone and email (and, now, Skype), technology didn’t offer a lot of options for families separated by distance—families like herself and her younger brother, but also divorced parents and their children, or military families dealing with overseas deployments.

This is how research ideas are born.

Yarosh is now on the cusp of filling this void with some technology of her own. Her project ShareTable is designed to facilitate meaningful, two-way interaction that goes beyond video chat. Through ShareTable, a parent and a child can play a board game together, or color in a coloring book, or work on the evening’s homework assignment. The system also is designed to be easy enough for a young child to operate; to turn it on, they would simply open the cabinet door to reveal their monitor.

“My main goal with ShareTable is to extend interactions between people,” said Yarosh, who was born in Russia and immigrated with her family to Maryland when she was 11. "Living so far away from my all of my extended family after we moved to America is what initially got me thinking that phones just weren't enough."

ShareTable is a simple concept that proved to be somewhat trickier in execution. Each station—and there must be two for every interaction—is equipped with two cameras that shoot video of the user’s face and a shared workspace on the table, as well as a projector that displays in virtually real time (depending on the Internet connection) images from the other user’s workspace camera. Thus not only do both users see and hear each other, they also see simultaneously what’s being produced on the workspace.

Problem-solving with computation, physics

Yarosh pulled all the technology for the ShareTable prototype off the shelf, and she predicts that cost ultimately would not be a significant limiting factor for the system. And though the test units are built into their furniture housing, she says future ShareTables could be mobile units adaptable to a user’s home environment.

Though it might have been readily available, the initial technology did present some challenges, most notably the “visual echo” created when two cameras are each filming the projected image of the other. For help, Yarosh turned to postdoctoral fellow Tony Tang of the School of Interactive Computing. Tang suggested moving to a pre-networked camera (rather than a conventional camera retrofitted to networking components), and he also converted ShareTable’s code from Python to C#. Finally, the cameras were yielding some image distortion, which Tang fixed in the code itself rather than in the hardware.

“Other people do this all the time,” Tang shrugs. “It was just a matter of pulling out the relevant bits and reintegrating them.”

Still, not all problems are fixed with computation, Yarosh says. “Some we had to solve with physics.”

To deal with the visual echo problem, the team turned to polarization. They incorporated lenses of different polarizations into the two cameras and projectors; light of one polarization could not be seen through a lens of a different polarization. Finally they incorporated a non-polarizing, silver lenticular projection screen as the ShareTable workspace, and voila—no more echo (or, at least, 95 percent less echo).

That’s not to say the system doesn’t have its limitations, most notably those imposed by bandwidth. When operated over a local area network, ShareTable works flawlessly, but most people have to deal with connections significantly slower. This forces a compromise between frame rate and image resolution, but it’s a compromise Yarosh hopes the future solves by building faster Internet for everyone.

“My understanding of what it takes to go from simply ‘It works!’ to ‘It works well enough to put in someone’s home’ has really evolved,” Yarosh says. “Especially because we’re dealing with small children as users. There need to be no surprises at all.”

Passion for child’s play

She should know about designing for kids. Yarosh’s advisor, Gregory Abowd, Distinguished Professor in the School of Interactive Computing, says she’s more sophisticated in it than he is—and this from a man whose major research focus is to develop technology that can help and support autistic children.

“Lana has always had a passion for designing for children,” Abowd says. “From the beginning, ShareTable has been something she developed, but she’s also worked on other interesting technologies that facilitate children’s play, such as videoconferencing. The point is to try to enrich their communications.

Her work has attracted like-minded colleagues. Sanika Mokashi, a master’s student in human-computer interaction from Pune, India, began working on ShareTable after watching Yarosh demo the project shortly after Mokashi arrived on campus in Fall 2010.

“I applied to Georgia Tech specifically because I wanted to work in this field—I want to learn by doing,” says Mokashi, whom her fellow ShareTable researchers call “the best coder on the team.”

In fact, most challenging in ShareTable’s evolution has been not the technical aspects or working with kids, but the testing. Staying true to its intended users, Yarosh has worked to find divorced parents with small children to pilot ShareTable in their own homes. This has proved more difficult than she’d like, but Yarosh is undaunted.

“I’ve found people to interview through long-distance parenting forums, through word of mouth,” she says. “The ability to talk to the people who could actually benefit from your work is incredibly motivating. It keeps my spirits up during the tough or slow times.”