VIDEO-ON-DEMAND and shopping in 3D will be available over the Internet within
a year, thanks to two new data compression techniques. Anyone with a standard
56k modem and an ordinary telephone line will be able to take advantage of the
new services.
The techniques are likely to produce a spate of new applications. John
Kingsbury, executive editor of BBC Online, says the BBC is very interested in
making the most of its 50 years of television archives. 鈥淭his is certainly a
technology that we could be interested in.鈥�
Forbidden Technologies, a high-tech start-up based in South London, says it
will offer VHS-quality video-on-demand by the end of the year. The company says
its streaming video technology will work with any Java-enabled Web browser
without needing extra software.
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The company鈥檚 technique compresses the data in the video, focusing only on
the parts of images that people perceive to be important. The compression
algorithm encodes skin tones far more accurately than other colours, for
example, and gives higher resolution to a person鈥檚 lips than to their clothes.
The result is that a speaker鈥檚 lip movements can be easily seen鈥攁lthough
small changes in the position of clothing are less clear-cut.
Stephen Streater at Forbidden Technologies says that the compression works
only with head-and-shoulder shots of people talking, but adds that the vast
majority of broadcasts are in this form. The technique cannot be applied to live
broadcasts because it is not possible to compress the data in real time鈥攕o
the main application will be previously converted videos.
Meanwhile, researchers in the US have developed a way of compressing 3D data
so efficiently that the shapes of human bodies, faces and internal organs could
soon be transmitted over standard Internet links. As well as helping in the
diagnosis of medical problems, the technique could lead to a new generation of
3D shopping and gambling on the Internet. It will enable people buying
furniture, for example, to examine the object from several different angles.
At present, the size and shape of a real object can be represented on the
computer as a surface made up of a dense mesh of interconnected triangles. One
way of storing this data is as the 3D coordinates of all the vertices in the
mesh. But this creates a huge amount of data, which would take ages to transmit
over a standard modem.
Wim Sweldens from Lucent Technologies鈥� Bell Labs in New Jersey and Peter
Schr枚der from the California Institute of Technology in Pasadena, realised
that they didn鈥檛 have to describe all three coordinates for each vertex. They
could just describe the perpendicular coordinate for each, together with a few
details about the basic shape of the object鈥攚hether it鈥檚 a sphere or a
doughnut, for example.
On screen, the basic shape acquires more details as more data is downloaded.
鈥淪o you can tell early on in the download process whether you have the wrong
file,鈥� says Sweldens.
The new technique, known as progressive geometry compression, will also allow
people to send and receive highly compressed 3D files over the Internet. 鈥淭he
big difference with our algorithm will be the low cost of the connection
needed,鈥� says Sweldens.