The Consumer Electronics Show in Las Vegas in January 2010 was abuzz
about a slew of prototype 3-D TVs, but if new research from the MIT Media
Lab is any indication, holographic TVs could be close behind.
At the Society of Photo-Optical Instrumentation Engineers' (SPIE)
Practical Holography conference in San Francisco the weekend of Jan.
23, members of Michael Bove's Object-Based Media Group presented a
new system that can capture visual information using off-the-shelf
electronics, send it over the Internet to a holographic display, and
update the image at rates approaching those of feature films.
In November, researchers at the University of Arizona made headlines
with an experimental holographic-video transmission system that used
16 cameras to capture data and whose display refreshed every two
seconds. The new MIT system uses only one data-capture device - the
new Kinect camera designed for Microsoft?s Xbox gaming system - and
averages about 15 frames per second. Moreover, the MIT researchers
didn?t get their hands on a Kinect until the end of December, and
only in the week before the conference did they double the system's
frame rate from seven to 15 frames per second. They're confident that
with a little more time, they can boost the rate even higher, to the
24 frames per second of feature films or the 30 frames per second of
TV rates that create the illusion of continuous motion.
The difference between holograms and the type of 3-D images becoming
common in movie theaters is frequently overlooked, Bove says. During
a screening of, say, the 3-D version of Avatar, viewers on the
far-left aisle of the theater see the same image that viewers on the
far-right aisle do. That image may have depth, but it's filmed from a
single perspective. As a viewer moves around a hologram, however, his
or her perspective on the depicted object changes continuously, just
as it would if the object were real.
A standard 3-D movie camera captures light bouncing off of an object
at two different angles, one for each eye. But in the real world,
light bounces off of objects at an infinite number of angles.
Holographic video systems use devices that produce so-called
diffraction fringes, fine patterns of light and dark that can bend
the light passing through them in predictable ways. A dense enough
array of fringe patterns, each bending light in a different
direction, can simulate the effect of light bouncing off of a
The challenge with real-time holographic video is taking video data -
in the case of the Kinect, the light intensity of image pixels and,
for each of them, a measure of distance from the camera - and, on the
fly, converting that data into a set of fringe patterns. Bove and his
grad students - James Barabas, David Cranor, Sundeep Jolly and Dan
Smalley - have made that challenge even tougher by limiting
themselves to off-the-shelf hardware.
"Really, the focus of our work in digital holography - and I think
this makes us pretty much unique among the very small community of
people in the world even doing holovideo - is that we?re trying to
make a consumer product," Bove says. "So we've been saying, How do
you make it as cheap as possible ? take advantage of hardware and
standards and software and everything else that already exists??
Because that's the quickest way to bring it to market."
In the group's lab setup, the Kinect feeds data to an ordinary
laptop, which relays it over the Internet. At the receiving end, a PC
with three commercial graphics processing units - GPUs - computes the
The one component of the researchers? experimental system that can't
be bought at an electronics store for a couple hundred dollars is the
holographic display itself. It's the result of decades of research
that began with MIT's Stephen Benton, who built the first holographic
video display in the late 1980s. (When Benton died in 2003, Bove?s
group inherited the holographic-video project.) The current project
uses a display known as the Mark-II, a successor to Benton's original
display that both Benton's and Bove's groups helped design. But Bove
says that his group is developing a new display that is much more
compact, produces larger images, and should also be cheaper to
manufacture. (Bove and his students reported on an early version of
the display at the same SPIE conference four years ago.)
Mark Lucente, director of display products for Zebra Imaging in
Austin, Texas, which is commercializing holographic displays for
videoconferencing applications, says that his company's prospective
customers are often uncomfortable with the sheer computational
intensity of holographic video. "It's very daunting," he says. "1.5
gigabytes per second are being generated on the fly." By
demonstrating that off-the-shelf components can keep up with the
computational load, Lucente says, Bove's group is "helping show that
it's within the realm of possibility." Indeed, he says, "by taking a
video game and using it as an input device, [Bove] shows that it's a
hop, skip and a jump away from reality."
When the Media Lab researchers demonstrate their new technology at
the conference in San Francisco, another grad student in Bove's
group, Edwina Portocarrero, sporting a cowled tunic and a wig with
side buns, will re-enact the scene from the first Star Wars movie in
which a hologram of Princess Leia implores Obi-Wan Kenobi to re-join
the battle against the evil empire. The resolution of the real
hologram won't be nearly as high as that of the special-effects
hologram in the movie, but as Bove points out, "Princess Leia wasn't
being transmitted in real time. She was stored."