Consumer holographic TV creeps closer to reality
Despite a relatively tepid consumer take-up, the buzz surrounding 3D television is still quite intense. But even the viewing improvements offered by stereoscopic technology may pale by comparison to the holographic goings-on at MIT. Researchers are taking the first steps toward making holographic technology a reality for consumers. Using primarily off-the-shelf components, the team has managed to capture, transmit and display a holographic subject on-the-fly.
Personally my holographic moment came when watching the TV adaptation of Douglas Adams' trilogy in five parts, The Hitch Hikers Guide to the Galaxy. Noted coastline designer Slartibartfarst appears as a holographic recorded announcement to the bemused occupants of the Heart of Gold spaceship. But for most people, the most memorable science fiction holographic image is that of Princess Leia asking Obi-Wan-Kenobi to rejoin the fight against the Empire from the first Star Wars movie. Now, rumblings of science fiction becoming science fact have emerged from the lab of MIT's Object-Based Media Group.
A matter of perspective
Whereas all viewers of so-called 3D films such as Avatar see the same image from the same perspective no matter where they sit in the theater, the perspective of holographic pictures changes depending on the viewing angle. A stereoscopic camera records light bouncing of an image at two slightly different angles that closely match each eye on a human face. This gives an illusion of depth, but in the real world light comes off objects at numerous angles all at once.
Holographic video systems don't require glasses in order to view a 3D image. They use devices that produce diffraction fringe patterns, light and dark streams that bend around objects in predictable ways. Bending the patterns in different directions can produce an image which looks truly three-dimensional but the process can be very computer-intensive. Zebra Imaging's Mark Lucente says that customers have been put off by the sheer computational intensity involved, "1.5 gigabytes per second are being generated on the fly."
Under the direction of Michael Bove, team members James Barabas, David Cranor, Sundeep Jolly and Dan Smalley set themselves the challenge of producing sets of fringe patterns using off-the-shelf hardware. They first tweaked a Kinect camera from Microsoft's X-Box gaming system so that it's frame capture rate was more than doubled to 15 frames per second (fps). The captured image was fed to a laptop which transmitted the data over the internet. A receiving PC sporting a threesome of commercially-available 3D graphics processors then calculated the diffraction patterns and sent the result to the one piece of the kit that's not available at consumer level ...
The Mark II holographic display
The Mark II holographic display was developed at MIT and is an updated version of holographic video display technology developed by Stephen Benton. Bove's group inherited the project after Benton's death and went on to develop its successor, which Benton's group helped design. The team is currently working on the development of a new display technology that's more compact but can produce larger images and should be cheaper to manufacture.
Help me Obi-Wan
The innovation was presented to attendees at the Practical Holography conference hosted by the Society of Photo-Optical Instrumentation Engineers in San Francisco recently. Edwina Portocarrero from Bove's group, decked out in tunic and wig, stood in for Carrie Fisher and re-enacted the famous holographic message, which was captured and displayed in real-time. It wasn't anywhere near the clarity of the movie version, but the latter was supplied by the Lucas special effects department and not generated on-the-fly using (mostly) consumer-level technology.Given time, the team reckons that they'll get that up to the 24 fps used for feature films or even right up to 30 fps used in television, which create the illusion of continuous motion.
Zebra's Lucentne said that "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."
Below is a video from the lab that shows MIT researchers achieve the highest frame rate yet for streaming holographic video: