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New movie screen allows for glasses-free 3D at a larger scale

25 July 2016

In a new paper, a team have demonstrated a display, called 'Cinema 3D', that lets audiences watch 3D films in a cinema without extra eyewear.

A new prototype display could show 3D movies to any seat in a theater, with no eyewear required. (Credit: Christine Daniloff/MIT)

The team are from MIT’s Computer Science and Artificial Intelligence Lab (CSAIL) and Israel’s Weizmann Institute of Science.

Dubbed “Cinema 3D,” the prototype uses a special array of lenses and mirrors to enable viewers to watch a 3D movie from any seat.

“Existing approaches to glasses-free 3D require screens whose resolution requirements are so enormous that they are completely impractical,” says MIT professor Wojciech Matusik, one of the co-authors on a related paper whose first author is Weizmann PhD Netalee Efrat. “This is the first technical approach that allows for glasses-free 3D on a large scale.”

While the researchers caution that the system isn’t currently market-ready, they are optimistic that future versions could push the technology to a place where cinemas would be able to offer glasses-free alternatives for 3D movies.

How it works

Glasses-free 3D already exists, but not in a way that scales to cinemas. Traditional methods for TV sets use a series of slits in front of the screen (a “parallax barrier”) that allows each eye to see a different set of pixels, creating a simulated sense of depth.

But because parallax barriers have to be at a consistent distance from the viewer, this approach isn’t practical for larger spaces like cinemas that have viewers at different angles and distances.

Other methods, including one from the MIT Media Lab, involve developing completely new physical projectors that cover the entire angular range of the audience. However, this often comes at a cost of lower image-resolution.

The key insight with Cinema 3D is that people in cinemas move their heads only over a very small range of angles, limited by the width of their seat. Thus, it is enough to display images to a narrow range of angles and replicate that to all seats in the cinema.

What Cinema 3D does, then, is encode multiple parallax barriers in one display, such that each viewer sees a parallax barrier tailored to their position. That range of views is then replicated across the cinema by a series of mirrors and lenses within Cinema 3D’s special optics system.

“With a 3D TV, you have to account for people moving around to watch from different angles, which means that you have to divide up a limited number of pixels to be projected so that the viewer sees the image from wherever they are,” says Gordon Wetzstein, an assistant professor of electrical engineering at Stanford University, who was not involved in the research. “The authors [of Cinema 3D] cleverly exploited the fact that cinemas have a unique set-up in which every person sits in a more or less fixed position the whole time.”

The team demonstrated that their approach allows viewers from different parts of an auditorium to see images of consistently high resolution.

Cinema 3D isn’t particularly practical at the moment: The team’s prototype requires 50 sets of mirrors and lenses, and yet is just barely larger than a pad of paper. But, in theory, the technology could work in any context in which 3D visuals would be shown to multiple people at the same time, such as billboards or storefront advertisements. Matusik says that the team hopes to build a larger version of the display and to further refine the optics to continue to improve the image resolution.

“It remains to be seen whether the approach is financially feasible enough to scale up to a full-blown cinema,” says Matusik. “But we are optimistic that this is an important next step in developing glasses-free 3D for large spaces like cinemas and auditoriums.”

This work was funded by the Israel Science Foundation and the European Research Council.  


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