Glasses-Free 3D TV;
Despite impressive recent advances, holographic television - which would present images that vary with varying perspectives - probably remains some distance in the future. The MIT Media Lab's Camera Culture group offers a new approach to multiple-perspective, glasses-free 3D that could prove much more practical in the short term. Instead of the complex hardware required to produce holograms, the Media Lab system uses several layers of liquid-crystal displays (LCDs). To produce a convincing 3D illusion, the displays would need to refresh at a rate of about 360 times a second, or 360 hertz. Such displays may not be far off - LCD TVs that boast 240-hertz refresh rates have already appeared on the market, just a few years after 120-hertz TVs made their debut.
Transcript
00:00:05 So we've all seen holograms in museums and gift shops. They look beautiful but we still can't go to the electronic store and buy that holographic television. So the question is why hasn't that happened yet? Well, one of the main reasons is that a holographic television will require pixels many times smaller than what we can manufacture even for our best mobile phones today. So what we're trying to do in our laboratory at MIT is develop 3-D technology that uses todays dominant display technology, which is liquid crystal panels, in a way that can create a beautiful
00:00:32 3-D scene like a hologram. As we move from two-dimensional displays to hyper-realistic, multi-dimensional displays for 3-D, or multispectral and lighting displays, the bandwidth requirements move from gigabytes-per-second to terabytes-per-second. But my using compressive displays we can explore compression not just in software but also in optics, and bring those bandwidth requirements within manageable limits. So what's our secret sauce? Well if you look at the natural
00:01:07 3-D world, say a white wall, it turns out as you move your head back and forth the wall doesn't really change. So what we do is we take compression algorithms, like you'd have in your digital camera, on your DVD or BluRay, we look at the world, we identify these redundancies and as a result we can actually use liquid crystal panels with those large pixels to create beautiful 3-D scenes that almost reach the quality of holograms today. Here the prototype is assembled in the directional backlight configuration. The front LCD layer sits atop a directional
00:01:37 backlight which is obscured while assembled. The LCD driver electronics are mounted with the panel on an aluminum plate. The plate is accurately positioned using a rail and clip system. From the side the location of the directional backlight, composed of a uniform backlight, LCD and lenses, can be more clearly seen behind front LCD. Because of the close layer spacing allowed by the directional backlight design our two-layer prototype has retained the thin form factor of an unmodified LCD panel. We now compare to the three-layer tensor display
00:02:11 prototype. In this configuration three LCD layers are illuminated by a uniform backlight. We choose a larger layer spacing to demonstrate the flexibility of the tensor framework, and to avoid moray interference without the need for custom holographic diffusers. Displayed 3-D images are perceived without any flickering but when filmed with a high-speed camera the temporally varying tensor decompositions are clearly visible for each of the three layers. So I think with new research you always want to ask,
00:02:40 why is this relevant now? And for us we're taking advantage of two big trends in display hardware and graphics hardware. The first is really high-speed display panels. This lets us show a bunch of frames that your eye adds up together as a single coherent image. The other trend we're taking advantage of is high-speed graphics hardware. The chips that go into your laptop, your phone, or your desktop PC have become so fast in the last five years that we can solve a whole complex computational problem in the time it takes to show just one frame of video. And this
00:03:14 has enabled a whole new way of thinking about 3-D display.