New glasses-free 3D technology allows for multiple viewers

Posted by Kate Taylor

Nintendo’s 3DS glasses-free 3D gaming device has been on sale for only a month - but it's already redundant, thanks to work from MIT.

Researchers at MIT’s Media Lab have developed a fundamentally new approach, dubbed HR3D, which they say can expand the viewing angle of a 3D screen, making it practical for larger devices with multiple users.

It also maintains the 3D effect even when the screen is rotated and doubles the battery life of devices, without compromising screen brightness or resolution.

The MIT team started with the idea that, in the real world, as viewers move around an object, their perspective on it changes constantly - meaning a convincing 3D experience could require a dozen different perspectives.

But with parallax-barrier 3D, adding multiple perspectives in the vertical direction as well as the horizontal would require bands in both axes. For a display with enough different views, the parallax barrier would end up practically solid.

The system they came up with uses two layers of liquid-crystal displays. But instead of displaying vertical bands, as the 3DS does, or pinholes, as a multiperspective parallax-barrier system would, the top LCD displays a pattern customized to the image beneath it.

In practice, the ideal pattern ends up looking a lot like the source image, with thousands of tiny slits, whose orientations follow the contours of the objects in the image.

Because the slits are oriented in so many different directions, the 3D illusion is consistent, no matter whether the image is upright or rotated 90 degrees. Adding more perspectives changes the pattern of the slits, but allows just as much light to pass.

If a device like the 3DS used HR3D, says the team, its battery life would be longer, because the parallax barrier would block less light. The 3-D effect would also be consistent no matter what the orientation - indeed, applications could actually take advantage of screen rotation, particularly in devices that have built-in motion sensors.

"The great thing about {Ramesh Raskar's] group is that they think of things that no one else has thought of, and then demonstrate that they can actually be done," says Neil Dodgson, professor of graphics and imaging at the University of Cambridge. "It’s quite a clever idea they’ve got here."