Interface blends screen and
Technology Research News
Email, telephone calls and even conferencing
software all fall far short of direct collaboration.
Researchers from the University of North Carolina at Chapel Hill
have devised a videoconferencing system that comes a step closer. Facetop
superimposes transparent images of a computer's desktop over video images
of the user to allow the user to look at the video and desktop at the
The video shows a ghostly mirror image of the user so that when
he points, his video reflection appears to touch objects on the screen.
The system tracks fingertip position in the video to allow the user to
control the mouse pointer.
As it turns out, the human visual/brain system "seems to be quite
good at paying attention to one and ignoring the other, depending on whether
you want to see the user or the desktop information," said David Stotts,
an associate professor of computer science at the University of North
Carolina at Chapel Hill.
The system can be used for remote teaching, PowerPoint presentations,
and as a basic PC interface with fingertip and pointing mouse control,
A two-user version combines the video streams of remote users
and presents the images side-by-side. This allows each person to control
the desktop, watch the other person control the desktop, and see the other's
face. A third version of the system allows users to hyperlink objects
in video image.
The system is especially appropriate for remote collaborations
where two people need to discuss some sort of document or artifact that
can be represented on a PC, including architectural and medical images,
software code, and Web documents, said Stotts. "Internet-based collaborations
have always been hampered by a lack of sense of presence, a lack of being
able to know what your partners are doing," he said. "Body language is
critical to understanding."
The system is easier to use than current videoconferencing systems
that put video and content in separate windows or screens because these
require the user to shift attention back and forth, said Stotts.
The idea came when one of the researchers was simultaneously running
a video application that had come with a camera and a PC whose display
was projected on the wall when a colleague came in to his office. "I happened
to have a small video application running... had pointed the camera back
at myself and... set it to reverse the horizontal direction like a mirror,"
"When Jason [Smith] and I were talking about something that was
on my PC desktop projected onto the wall... I reached my hand into the
air so that... my image on the screen also was pointing to the item on
the desktop," said Stotts. "Jason saw that and said 'what if we made that
full-screen', and we were off," he said. "We added the idea of transparency
so that the entire desktop would show through."
The system is relatively inexpensive to implement, said Stotts.
"All we need is a $100 FireWire camera, a Macintosh and the Internet,"
he said. The system's software controls the transparency effect and the
The technical challenges were getting the transparency to work
so that user applications did not shut it off, carrying out finger tracking
quickly enough to match the 30-frames-a-second video, and sending a video
signal over the Internet, said Stotts.
The system contains a setting that turns the transparent video
on and off when the user raises a hand into the camera view. "This is
nice for PowerPoint presentations," said Stotts. In one experiment, the
researchers were able to allow two users who have hearing disabilities
to have a video-based signing conversation using the software, he said.
The user can set the level of transparency, said Stotts. "Some
users like to see a lot of face mixed in with their [desk]top, others
like a faint video image."
The third version of the system, dubbed FaceSpace, allows users
to create hyperlinks for objects in the video image. A second camera is
aimed at a whiteboard and this image is mixed into the FaceTop composite.
Words, symbols and lines drawn on the whiteboard appear to float over
objects in the user video image. The system lets users create hyperlink
hotspots for markings on the whiteboard or objects in the user video.
A Macintosh version of FaceTop could be implemented within a few
months, and a PC version within two years, according to Stotts. The PC
version would have to wait for the next major version of the Windows operating
system, which will have the needed technical infrastructure, he said.
The researchers are working on a multi-person version of the system,
are performing studies of how well the system works for collaborative
programming, and are adapting a version that can be used with wide, very
high quality displays.
Stotts's research colleagues were Jason McC. Smith and Karl Gyllstrom.
The research was funded by the U.S. Environmental Protection Agency (EPA).
Timeline: > 2 years
TRN Categories: Human-Computer Interaction
Story Type: News
Related Elements: Technical papers, "Synchronous Pair Collaborations
Support with the Transparent Video Facetop," posted at http://rockfish-cs.cs.unc.edu/pubs/TR04-008.pdf;
"Distributed Collaborations in Facetop" posted at ;
"FaceSpace: Endo- and Exo-Spatial Hypermedia in the Transparent Video
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