Stanford Uni develops technique to see objects around corners

Posted on 7 Mar 2018 by Jonny Williamson

Researchers from Stanford University, CA, have developed a laser-based imaging technology that can peak around the corner and could enable self-driving cars to react to hazards before the drivers sees them.  

Graduate student David Lindell and Matt O’Toole, a post-doctoral scholar work in the lab.

Stanford University researchers created the following scenario to imagining for a system that can produce images of objects hidden from view:

‘A driverless car is making its way through a winding neighbourhood street, about to make a sharp turn onto a road where a child’s ball has just rolled.

Although no person in the car can see that ball, the car stops to avoid it. This is because the car is outfitted with extremely sensitive laser technology that reflects off nearby objects to see around corners.’

The researchers are focused on applications for autonomous vehicles, some of which already have similar laser-based systems for detecting objects around the car.

But other uses could include seeing through foliage from aerial vehicles or giving rescue teams the ability to find people blocked from view by walls and rubble.

Gordon Wetzstein, assistant professor of Electrical Engineering and of Computer Science at Stanford University, said: “It sounds like magic but the idea of non-line-of-sight imaging is actually feasible.”

Seeing the unseen

The Stanford group isn’t alone in developing methods for bouncing lasers around corners to capture images of objects. Where this research advances the field is in the extremely efficient and effective algorithm the researchers developed to process the final image.

David Lindell, graduate student in the Stanford Computational Imaging Lab, said: “A substantial challenge in non-line-of-sight imaging is figuring out an efficient way to recover the 3-D structure of the hidden object from the noisy measurements. I think the big impact of this method is how computationally efficient it is.”

For their system, the researchers set a laser next to a highly sensitive photon detector, which can record even a single particle of light.

They shoot pulses of laser light at a wall and, invisible to the human eye, those pulses bounce off objects around the corner and bounce back to the wall and to the detector.

Currently, this scan can take from two minutes to an hour, depending on conditions such as lighting and the reflectivity of the hidden object.

Once the scan is finished, the algorithm untangles the paths of the captured photons and, like the mythical image enhancement technology of television crime shows, the blurry blob takes much sharper form.

It does all this in less than a second and is so efficient it can run on a regular laptop.

Based on how well the algorithm currently works, the researchers think they could speed it up so that it is nearly instantaneous once the scan is complete.

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