快猫短视频

NOT much gets past the eagle-eyed sentries who guard the Internet gateway at
the University of North Carolina at Chapel Hill. You鈥檇 be ultra-vigilant too, if
you were watching over Internet2, the prototype next-generation Net. So when, on
9 May, the electronic traffic suddenly surged to more than four times its normal
level, alarms began to ring and panic set in. Someone, somewhere was driving
juggernaut-sized wodges of data over the Net. This was big . . . really big.

A swift investigation revealed that the culprits, led by UNC computer
scientists Henry Fuchs and Greg Welch, had just opened a pair of portals
connecting Chapel Hill with Philadelphia and New York. Through these portals,
they could peer into the offices of colleagues hundreds of miles away, in
life-sized three dimensions and real time. It was as if they had teleported
distant chunks of space into their laboratory.

The experiment was the first demonstration of tele-immersion, which could
radically change the way we communicate over long distances. Tele-immersion will
allow people in different parts of the world to submerge themselves in one
another鈥檚 presence and feel as if they are sharing the same physical space. It鈥檚
the real-world answer to the Star Trek Holodeck, the projection
chamber on the Starship Enterprise where crew members interact with projected
images as if they were real. 鈥淲e call it 鈥榖eing there鈥�,鈥� says Welch.

May鈥檚 experiment was the culmination of three years鈥� work by the National
Tele-Immersion Initiative (NTII), a project led by virtual reality pioneer Jaron
Lanier. The test linked three of the members of the group: UNC Chapel Hill, the
University of Pennsylvania in Philadelphia, and a non-profit organisation called
Advanced Network and Services in Armonk, New York, where Lanier is chief
scientist.

At Chapel Hill, there were two large screens, hung at right angles above a
desk, plus projection cameras and head tracking gear. The screens were flat and
solid, but once the demo was up and running they looked more like windows.
Through the left-hand screen, Welch could see colleagues in Philadelphia as if
they were sitting across the desk from him. The right-hand screen did the same
for Armonk. When Welch changed his point of view, the images shifted in a
natural way. If he leaned in, the images got larger, if he leaned out they got
smaller. He could even crane his neck to look round the people.

To make it work, both target sites were kitted out with arrays of digital
cameras to capture images and laser rangefinders to gather positional
information. Computers then converted the images into 3D geometrical information
and transmitted it to Chapel Hill via Internet2. There, computers reconstructed
the images and projectors beamed them onto the screens.

The images were split and polarised to create a slightly different image for
each eye, much like an old-fashioned 3D movie. Welch wore glasses with
differently oriented polarising lenses so his left eye saw one image and his
right eye the other, which his brain combined to produce 3D images. A
head-mounted tracker followed Welch鈥檚 movements and changed the images on the
screens accordingly.

Like the first transcontinental phone call, the quality was scratchy. It was
also jerky, updating around three times a second rather than 10, the minimum
speed needed to capture the full range of facial expressions. And it only worked
one-way: the people in Armonk and Philadelphia couldn鈥檛 see Chapel Hill.
Nevertheless, it moved UNC video services manager Thomas Cox to say: 鈥淚t looks
like somebody took a chainsaw and cut a hole in the wall and he鈥檚 on the other
蝉颈诲别.鈥�

All this may sound like conventional videoconferencing. But tele-immersion is
much, much more. Where videoconferencing delivers flat images to a screen,
tele-immersion recreates an entire remote environment. 鈥淭he person is projected
life-size in 3D around you, and you can look behind them,鈥� says Kostas
Daniilidis of the Pennsylvania tele-immersion team.

It鈥檚 easy to dream up applications for such a technology. Business people on
different continents could conduct face-to-face meetings. Schoolchildren in
China, Australia or Britain could walk beneath massive dinosaur bones in a
museum in New York. Patients in remote areas could see a doctor. And once
haptics鈥攖ouch simulators鈥攁re built in, people could use
tele-immersion to come together in even stranger ways. A woman in Europe could
reach out and touch her newborn grandchild in the US.

But not yet. Problem is, today鈥檚 Internet can鈥檛 ship data fast enough. To
look anything like reality, tele-immersion will have to be able to move
mountains of data鈥攕patial and visual information about people and their
environments鈥攁cross the Internet in a trice. Today鈥檚 56-kilobit-per-second
connections can鈥檛 do that. Even the bare-bones demonstration at Chapel Hill
needed 60 megabits per second. High-quality tele-immersion will require even
more鈥攁round 1.2 gigabits per second.

Pioneering spirit

Fortunately, that kind of capacity is on its way. Leading the charge is
Internet2, a consortium of American universities, government agencies, private
companies and international organisations that is trying to recreate the
collaborative spirit of the early Internet. The group is building high-speed
networks and developing software with the aim of transmitting data at speeds an
order of magnitude faster than the Net does now. The project鈥檚 leaders say it is
a unique test bed for Internet applications of the future, including
tele-immersion.

In addition to high-speed networks, tele-immersion will require
supercomputers to perform the trillions of calculations that are needed to
portray environments in 3D. This kind of computer power would have to be on tap
over the Internet. Something like that is on the way, too, in the form of a
network called the Grid
(see 鈥淧ower sharing鈥�).

In the next tele-immersion experiment, the teams will open two-way portals so
that all three locations can see and hear one another. They will then try out a
dummy collaborative project: rearranging the furniture in a doll鈥檚 house.

Eventually the researchers would like to make tele-immersion even more
naturalistic, perhaps by jettisoning the headgear and glasses altogether. One
possibility is to use a screen that transmits different information to each eye,
using swivelling pixels that track either the left or right eye. Another idea is
to turn the entire tele-immersion room into a screen. Walls, tables, curtains,
even floors could be coated with special light-sensitive material. Cameras would
photograph the surfaces, computers would calculate their shapes in 3D, and
projectors would shine pre-warped images, making it seem as if they filled the
room.

Tele-immersion may seem like another kind of virtual reality, but Lanier says
it鈥檚 something different. And he should know: he coined the term. Virtual
reality, he says, allows people to move around in a pre-programmed
representation of a 3D environment, whereas tele-immersion is more like
photography. 鈥淚t鈥檚 measuring the real world and conveying the results to the
sensory system,鈥� he says.

But that doesn鈥檛 mean there鈥檚 no place for virtual reality within
tele-immersion systems. The NTII researchers are working on incorporating
virtual objects that can be seen, manipulated and altered by all the
participants. 鈥淲e might want to look at the design of a product together,鈥� says
Welch. Meanwhile, Tom Defanti and his colleagues from the University of Illinois
at Chicago are taking the marriage of tele-immersion and virtual reality a step
further. In their systems, people share a virtual environment and each is
visible to the others as a computer simulated entity, or 鈥渁vatar鈥�. People could
choose the way they look in a tele-immersion session鈥攆rom changing their
hair colour to looking like a film star.

Defanti thinks that such technology would enable researchers to collaborate
in fields such as architecture, medicine, astrophysics and aeroplane design. The
beauty of it is that it allows widely separated people to share a complex
virtual experience. 鈥淵ou might be testing a vehicle,鈥� says Defanti. 鈥淵ou want to
smash it into the wall at 40 miles per hour and put your head by the cylinder
block. Say there鈥檚 a guy from Sweden and you have to prove to him that it
doesn鈥檛 move by 3 centimetres or more. That kind of stuff works.鈥�

But tele-immersion is not just a research tool. The fast-food chain McDonalds
showed interest at one early workshop, says Defanti. McDonalds envisioned
fitting tele-immersion booths in its restaurants so people away from home could
have dinner with their family. 鈥淭he technology for that is not that far off,鈥�
says Defanti. The gaming industry is another potential user. Players could
tele-immerse themselves in a virtual reality environment, chasing monsters or
firing phasers at each other.

All of this, of course, relies on other emerging technologies. Most important
is the ability of the Internet to ship vast amounts of data across continents
without delay. Luckily for the developers of tele-immersion, their needs are at
the forefront of Internet2鈥檚 thoughts. In fact, the two projects go hand in
hand. Internet2 needs a raison d鈥櫭猼re for its increased capacity, and in
tele-immersion it seems to have found one. The experiment at Chapel Hill in May
was made possible by UNC鈥檚 Internet2 link. 鈥淭here is simply no other known
application that would push the network to its limits,鈥� says Lanier.