Subscribe free to our newsletters via your
. 24/7 Space News .




TECH SPACE
Glasses-free 3-D projector
by Larry Hardesty, MIT News Office
Boston MA (SPX) May 20, 2014


The MIT Media Lab's Camera Culture group introduces a novel approach to multiple-perspective, glasses-free 3-D. Watch a vdeo on the research here.

Over the past three years, researchers in the Camera Culture group at the MIT Media Lab have steadily refined a design for a glasses-free, multiperspective, 3-D video screen, which they hope could provide a cheaper, more practical alternative to holographic video in the short term.

Now they've designed a projector that exploits the same technology, which they'll unveil at this year's Siggraph, the major conference in computer graphics. The projector can also improve the resolution and contrast of conventional video, which could make it an attractive transitional technology as content producers gradually learn to harness the potential of multiperspective 3-D.

Multiperspective 3-D differs from the stereoscopic 3-D now common in movie theaters in that the depicted objects disclose new perspectives as the viewer moves about them, just as real objects would. This means it might have applications in areas like collaborative design and medical imaging, as well as entertainment.

The MIT researchers - research scientist Gordon Wetzstein, graduate student Matthew Hirsch, and Ramesh Raskar, the NEC Career Development Associate Professor of Media Arts and Sciences and head of the Camera Culture group - built a prototype of their system using off-the-shelf components.

The heart of the projector is a pair of liquid-crystal modulators - which are like tiny liquid-crystal displays (LCDs) - positioned between the light source and the lens. Patterns of light and dark on the first modulator effectively turn it into a bank of slightly angled light emitters - that is, light passing through it reaches the second modulator only at particular angles. The combinations of the patterns displayed by the two modulators thus ensure that the viewer will see slightly different images from different angles.

The researchers also built a prototype of a new type of screen that widens the angle from which their projector's images can be viewed. The screen combines two lenticular lenses - the type of striated transparent sheets used to create crude 3-D effects in, say, old children's books.

Exploiting redundancy
For every frame of video, each modulator displays six different patterns, which together produce eight different viewing angles: At high enough display rates, the human visual system will automatically combine information from different images.

The modulators can refresh their patterns at 240 hertz, or 240 times a second, so even at six patterns per frame, the system could play video at a rate of 40 hertz, which, while below the refresh rate common in today's TVs, is still higher than the 24 frames per second standard in film.

With the technology that has historically been used to produce glasses-free 3-D images - known as a parallax barrier - simultaneously projecting eight different viewing angles would mean allotting each angle one-eighth of the light emitted by the projector, which would make for a dim movie.

But like the researchers' prototype monitors, the projector takes advantage of the fact that, as you move around an object, most of the visual change takes place at the edges. If, for instance, you were looking at a blue mailbox as you walked past it, from one step to the next, much of your visual field would be taken up by a blue of approximately the same shade, even though different objects were coming into view behind it.

Algorithmically, the key to the researchers' system is a technique for calculating how much information can be preserved between viewing angles and how much needs to be varied. Preserving as much information as possible enables the projector to produce a brighter image.

The resulting set of light angles and intensities then has to be encoded into the patterns displayed by the modulators. That's a tall computational order, but by tailoring their algorithm to the architecture of the graphics processing units designed for video games, the MIT researchers have gotten it to run almost in real time. Their system can receive data in the form of eight images per frame of video and translate it into modulator patterns with very little lag.

Bridge technology
Passing light through two modulators can also heighten the contrast of ordinary 2-D video. One of the problems with LCD screens is that they don't enable "true black": A little light always leaks through even the darkest regions of the display. "Normally you have contrast of, let's say, values between 0 and 1," Wetzstein explains.

"That's the full contrast, but in practice, all modulators have something like 0.1 to 1. So you get this 'black level.' But if you multiply two optically together, the black level goes down to 0.01. If you show black on one, which is 10 percent, and black on the other, which is also 10 percent, what you get through is 1 percent. So it's much more black."

By the same token, Hirsch explains, if the patterns displayed on the modulators are slightly offset from each other, the light passing through them will interfere with itself in ways that actually heighten the resolution of the resulting images. Again, the researchers have developed an algorithm that can calculate those patterns on the fly.

As content creators move to so-called "quad HD," video with four times the resolution of today's high-definition video, the combination of higher contrast and higher resolution could make a commercial version of the researchers' technology appealing to theater owners, which in turn could smooth the way for the adoption of multiperspective 3-D.

"One thing you could do - and this is what actual projector manufacturers have done in the recent past - is take four 1080p modulators and put them next to each other and build some very complicated optics to tile them all seamlessly and then get a much nicer lens because you have to project a much smaller spot and bundle that all up together," Hirsch says.

"We're saying you could take two 1080p modulators, stick them in your projector one after the other, then take your same old 1080p lens and project through it and use this software algorithm, and you end up with a 4k image. But not only that, it's got even higher contrast."

.


Related Links
Massachusetts Institute of Technology
Space Technology News - Applications and Research






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle








TECH SPACE
Engineering Breakthrough Will Allow Cancer Researchers to Create Live Tumors With a 3D Printer
Philadelphia PA (SPX) Apr 30, 2014
Drexel's Wei Sun, PhD, Albert Soffa chair professor in the College of Engineering, has devised a method for 3D printing tumors that could soon be taking cancer research out of the petri dish. Using a mixture of cervical cancer cells and a hydrogel substance that resembles an ointment balm, Sun can print out a tumor model that can be used for studying their growth and response to treatment. ... read more


TECH SPACE
LRO View of Earth

Saturn in opposition tonight, will appear next to the moon

Russia to begin Moon colonization in 2030

Astrobotic Partners With NASA To Develop Robotic Lunar Landing Capability

TECH SPACE
NASA Mars Rover Curiosity Wrapping Up Waypoint Work

Cascading dunes in a martian crater

MAVEN Solar Wind Ion Analyzer Will Look at Key Player in Mars Atmosphere Loss

Against the current with lava flows

TECH SPACE
A light-speed voyage to the distant future

US spacecraft enters giant asteroid's orbit

Chris Hadfield's 'Space Oddity' video to be taken off YouTube

'Convergent' Research Solves Problems that Cross Disciplinary Boundaries

TECH SPACE
Moon rover Yutu comes closer to public

The Phantom Tiangong

New satellite launch center to conduct joint drill

China issues first assessment on space activities

TECH SPACE
Rounding up the BCATs on the ISS

Botanical Studies, Dragon Departure Preps for ISS Crew

NASA hopes to continue cooperation with Russia on ISS

Three astronauts land back on Earth in Soyuz capsule

TECH SPACE
SpaceX-3 Mission To Return Dragon's Share of Space Station Science

SpaceX supply capsule heads back to Earth

Replacing Russian-made rocket engines is not easy

Pre-launch processing begins for the O3b Networks satellites

TECH SPACE
Giant telescope tackles orbit and size of exoplanet

Odd planet, so far from its star

New Exomoon Hunting Technique Could Find Solar System-like Moons

Length of Exoplanet Day Measured for First Time

TECH SPACE
Is there really cash in your company's trash?

Computer simulations enable better calculation of interfacial tension

Professors' super waterproof surfaces cause water to bounce like a ball

New Technique Safely Penetrates Top Coat for Perfect Paint Job




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.