New movie display allows for glasses-free 3-D for a theater audience

July 29, 2016

A new prototype display could show 3-D movies to any seat in a theater — no eyewear required (credit: Christine Daniloff / MIT)

A new “Cinema 3D” display lets audiences watch 3-D films in a movie theater without cumbersome glasses.

Developed by a team from MIT’s Computer Science and Artificial Intelligence Lab (CSAIL) and Weizmann Institute of Science, the prototype display uses a special array of lenses and mirrors to enable viewers to watch a 3-D movie from any seat in a theater.

Left: the standard approach to the design of automultiscopic 3D displays, which attempts to cover the angular range of all viewer positions, but involves poor spatial/angular resolution or a restricted range of screen distances. Right: an automultiscopic 3D display architecture that only presents a narrow range of angular images across the small set of viewing positions of a single seat, and replicates that narrow-angle content to all seats in the cinema and at all screen distances. (credit: Netalee Efrat et al./ACM Trans.Graph., )

Glasses-free 3-D already exists: 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 theaters, which 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 movie theaters move their heads only over a very small range of angles, limited by the width of their seat. So it’s enough to display images to a narrow range of angles and replicate that to all seats in the theater, using a series of mirrors and lenses. (The team’s prototype requires 50 sets of mirrors and lenses, which is currently expensive and impractical, the researchers say.)

The team presented Cinema 3D in an open-access paper at last week’s SIGGRAPH computer-graphics conference in Anaheim, California. The work was funded by the Israel Science Foundation and the European Research Council.

MITCSAIL | Cinema 3D: A movie screen for glasses-free 3D

Abstract of Cinema 3D: large scale automultiscopic display

While 3D movies are gaining popularity, viewers in a 3D cinema still need to wear cumbersome glasses in order to enjoy them. Automultiscopic displays provide a better alternative to the display of 3D content, as they present multiple angular images of the same scene without the need for special eyewear. However, automultiscopic displays cannot be directly implemented in a wide cinema setting due to variants of two main problems: (i) The range of angles at which the screen is observed in a large cinema is usually very wide, and there is an unavoidable tradeoff between the range of angular images supported by the display and its spatial or angular resolutions. (ii) Parallax is usually observed only when a viewer is positioned at a limited range of distances from the screen. This work proposes a new display concept, which supports automultiscopic content in a wide cinema setting. It builds on the typical structure of cinemas, such as the fixed seat positions and the fact that different rows are located on a slope at different heights. Rather than attempting to display many angular images spanning the full range of viewing angles in a wide cinema, our design only displays the narrow angular range observed within the limited width of a single seat. The same narrow range content is then replicated to all rows and seats in the cinema. To achieve this, it uses an optical construction based on two sets of parallax barriers, or lenslets, placed in front of a standard screen. This paper derives the geometry of such a display, analyzes its limitations, and demonstrates a proof-of-concept prototype.