Seeing around corners

Reflected light gets everywhere and even shady spots are full of images we can’t see – not least what’s happening around corners. But new technology is beginning to expose these hidden scenes

NOTHING to see here: just an image of an empty street. But the investigator thinks there is more to this than meets the eye. With a few clicks of his mouse, he enhances a featureless shadow cast on the floor, apparently defying the laws of optics to extract a blurry image of two people lurking around the corner.

Technical wizardry like this seems far-fetched. But this isn’t CSI. The investigator is a computer scientist not a detective, and those characters are graduate students not suspects. More importantly, this technology is real, and it is being developed in labs right now.

The science of seeing around corners is new, fast-moving and breathtaking. We are discovering that the shadows are full of visual information that our eyes can’t see. Now, as people develop clever ways to make the invisible visible, they are exposing all manner of potential applications besides forensics. Autonomous cars that spot hidden hazards. Cameras that direct fire crews to people trapped in burning buildings. Endoscopes that guide surgery in unreachable parts of the body.

“It could be extremely powerful,” says Vickie Ye, a computer vision researcher at the University of California, Berkeley. “Any information outside the frame could be interpretable.” […]

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