Seeing around corners

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.

I wonder how much this could be used to process old data and reveal new information from historic documents.

Researchers in Freeman’s group have started integrating passive and active approaches. A paper led by the postdoctoral researcher Christos Thrampoulidis showed that in active imaging with a laser, the presence of a pinspeck camera of known shape around a corner can be used to reconstruct the hidden scene, without requiring photon time-of-flight information at all. “We should be able to do it with a regular CCD camera,” Thrampoulidis said.

Non-line-of-sight imaging could someday aid rescue teams, firefighters and autonomous robots. Velten is collaborating with NASA’s Jet Propulsion Laboratory on a project aimed at remote-imaging the insides of caves on the moon. Meanwhile, Raskar and company have used their approach to read the first few pages of a closed book and to see a short distance through fog.

https://www.quantamagazine.org/the-new-science-of-seeing-around-corners-20180830/