Sharing A Vision
by David Pescovitz
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A
snapshot of the ShareCam interface with a view of the Stanley
Hall construction site.
Courtesy the researchers
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Nobody wants to
wait in line. This is especially true on the World Wide Web, where
myriad distractions are just a mouse-click away. UC Berkeley professor
Ken Goldberg and graduate student Dezhen Song are tackling this
problem with regard to telerobotic webcams, Internet-connected video
cameras that users currently queue up to control. ShareCam, the
researchers' collaboratively-operated robotic webcam system, eliminates
the wait.
"We wanted to create a way for a robotic webcam to be controlled
by many people at once," says Goldberg, who holds a joint faculty
position in the Department of Industrial Engineering and Operations
Research and the Department of Electrical Engineering and Computer
Sciences.
Commercially-available and inexpensive webcams with pan, tilt, and
zoom controls are being installed in hundreds of locations, from
Hiroshima Harbor to the Giant Panda habitat at the National Zoo.
The conundrum, Goldberg explains, is that the more popular a webcam,
the fewer number of people get to use it.
"When there's
a lot of demand, robotic webcam systems simply don't scale," he
says. On the other hand, ShareCam could potentially scale to millions
of simultaneous users, Goldberg adds.
To participate
in the collaborative control of ShareCam, users register online
and select a color to represent themselves. The ShareCam interface
contains two windows. The first provides a streaming video view
from the camera's lens. The second window depicts a static image
of the camera's entire range of vision. A user simply draws a box,
or frame, around the portion of the image he'd like the camera to
hone in on. The size of the frame characterizes the zoom of the
camera. Meanwhile, nineteen other users do the same thing. The computer
then tallies the user requests and calculates an "optimal" single
frame. The camera then shifts its gaze to that frame.
Ken
Goldberg is the editor of two books on Internet telerobotics,
both published by MIT Press: The Robot in the Garden
and (with Roland Siegwart) Beyond Webcams.
Bart Nagel photo
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The magic of the ShareCam software is its ability to please most
of the people, all of the time. A seemingly obvious approach would
be to average all of the votes to determine the camera's next position.
Failure quickly occurs though, Goldberg says.
"If you have a bunch of votes to move right and a bunch to move
left, the camera would end up moving to the middle of the picture,
which nobody wants," he says. "So we needed a more sophisticated
model that resolves conflict between all the different votes."
Goldberg and Song came up with a novel satisfaction metric, a method
to measure the satisfaction of each user with respect to the potential
camera frame computed from the votes. The researchers then devised
new algorithms that enable the system to find a camera frame that
optimizes the measure of total user satisfaction.
"The algorithms
are very fast and very computationally efficient," Goldberg says.
The ShareCam research ties directly to Goldberg's online experiments
in collaborative filtering, the notion that people who agreed in
the past will probably agree in the future. The project also follows
Goldberg and his team's development of the TeleActor, a system where
users democratically control a human "robot" to explore remote spaces.
Like the TeleActor, the ShareCam project is part of a larger distance
learning effort in the Berkeley-based Center for Information Technology
Research in the Interest of Society (CITRIS).
A prototype ShareCam is now mounted outside of the new Stanley Hall
construction site. When completed, the Stanley Hall Biosciences
and Bioengineering Facility will house laboratories for CITRIS,
the California Institute for Quantitative Biomedical Research (QB3),
and the Department of Bioengineering.
"We want to place cameras where there's a lot of public interest,"
Goldberg says. "We've also talked about locations like a live volcano
or in a war zone — anywhere lots of people would like to see
but it's not practical to install very many cameras."
ShareCam
Ken Goldberg's Home Page
Dezhen Song's Home Page
Center for Information Technology Research in the Interest of Society (CITRIS)
Lab Notes is published online by the Public Affairs Office of the UC Berkeley College of Engineering. The Lab Notes mission is to illuminate groundbreaking
research underway today at the College of Engineering that will dramatically change our lives tomorrow.
Editor, Director of Public Affairs: Teresa Moore
Writer, Researcher: David Pescovitz
Designer: Robyn Altman
Subscribe or send comments to the Engineering Public Affairs Office: lab-notes@coe.berkeley.edu.
© 2003 UC Regents.
Updated 5/30/03.
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