Multiview 3-D photography made simple

A new technique enables the conversion of an ordinary camera into a light-field camera capable of recording high-resolution, multiperspective images.

Computational photography is the use of clever light-gathering tricks and sophisticated algorithms to extract more information from the visual environment than traditional cameras can.

The first commercial application of computational photography is the so-called light-field camera, which can measure not only the intensity of incoming light but also its angle. That information can be used to produce multiperspective 3-D images, or to refocus a shot even after it’s been captured.

Existing light-field cameras, however, trade a good deal of resolution for that extra angle information: A camera with a 20-megapixel sensor, for instance, will yield a refocused image of only one megapixel.

Researchers in the Camera Culture Group at MIT’s Media Lab aim to change that with a system they’re calling Focii. At this summer’s Siggraph — the major computer graphics conference — they’ll present a paper demonstrating that Focii can produce a full, 20-megapixel multiperspective 3-D image from a single exposure of a 20-megapixel sensor.

Moreover, while a commercial light-field camera is a $400 piece of hardware, Focii relies only on a small rectangle of plastic film, printed with a unique checkerboard pattern, that can be inserted beneath the lens of an ordinary digital single-lens-reflex camera. Software does the rest.

Gordon Wetzstein, a postdoc at the Media Lab and one of the paper’s co-authors, says that the new work complements the Camera Culture Group’s ongoing research on glasses-free 3-D displays. “Generating live-action content for these types of displays is very difficult,” Wetzstein says. “The future vision would be to have a completely integrated pipeline from live-action shooting to editing to display. We’re developing core technologies for that pipeline.”

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In 2007, Ramesh Raskar, the NEC Career Development Associate Professor of Media Arts and Sciences and head of the Camera Culture Group, and colleagues at Mitsubishi Electric Research showed that a plastic film with a pattern printed on it — a “mask” — and some algorithmic wizardry could produce a light-field camera whose resolution matched that of cameras that used arrays of tiny lenses, the approach adopted in today’s commercial devices. “It has taken almost six years now to show that we can actually do significantly better in resolution, not just equal,” Raskar says.

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