(Roughly) Daily

“There is one thing which gives radiance to everything. It is the idea of something around the corner”*…

 

around corners

 

While vacationing on the coast of Spain in 2012, the computer vision scientist Antonio Torralba noticed stray shadows on the wall of his hotel room that didn’t seem to have been cast by anything. Torralba eventually realized that the discolored patches of wall weren’t shadows at all, but rather a faint, upside-down image of the patio outside his window. The window was acting as a pinhole camera — the simplest kind of camera, in which light rays pass through a small opening and form an inverted image on the other side. The resulting image was barely perceptible on the light-drenched wall. But it struck Torralba that the world is suffused with visual information that our eyes fail to see.

“These images are hidden to us,” he said, “but they are all around us, all the time.”

The experience alerted him and his colleague, Bill Freeman, both professors at the Massachusetts Institute of Technology, to the ubiquity of “accidental cameras,” as they call them: windows, corners, houseplants and other common objects that create subtle images of their surroundings. These images, as much as 1,000 times dimmer than everything else, are typically invisible to the naked eye. “We figured out ways to pull out those images and make them visible,” Freeman explained.

The pair discovered just how much visual information is hiding in plain sight. In their first paper, Freeman and Torralba showed that the changing light on the wall of a room, filmed with nothing fancier than an iPhone, can be processed to reveal the scene outside the window. Last fall, they and their collaborators reported that they can spot someone moving on the other side of a corner by filming the ground near the corner. This summer, they demonstrated that they can film a houseplant and then reconstruct a three-dimensional image of the rest of the room from the disparate shadows cast by the plant’s leaves. Or they can turn the leaves into a “visual microphone,” magnifying their vibrations to listen to what’s being said…

Computer vision researchers have uncovered a world of visual signals hiding in our midst, including subtle motions that betray what’s being said and faint images of what’s around a corner: “The New Science of Seeing Around Corners.”

* G. K. Chesterton

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As we crane our necks, we might send infectious birthday greetings to Mary Mallon; she was born on this date in 1869.  Better known by the nickname given her by the press, “Typhoid Mary,” she was the first person in the United States identified (in 1915) as an asymptomatic carrier of the pathogen associated with typhoid fever… before which, she inadvertently spread typhus for years while working as a cook in the New York area.  From 1915 to 1938, when she died of s stroke, she was quarantined on North Brother Island (in the East River, between Riker’s Island and the Bronx).

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Written by LW

September 23, 2018 at 1:01 am

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