According to a page on the Stanford Computational Imaging Lab’s website, having a private room is a basic condition of functional living for most of us, but researchers have described a novel method called non-line-of-sight imaging that could expose every physical object within by peering through a keyhole with a single laser light.
To put it another way, this new method converts your keyhole into a peephole.
To function, the new laser technique requires large flat surfaces.
Non-line-of-sight (NLOS) imaging is a well-established technique that has been refined through ongoing research to create cameras that can image objects hidden behind corners beyond the field of view.
Previously, this technique used flat surfaces, such as walls or floors, that happened to be in line-of-sight with the hidden object and the camera, allowing light pulses from the camera (typically lasers) to bounce off of the flat surface and back to the camera’s sensors.
This data was then analyzed by algorithms, which calculated the time between sending and receiving the signal in order to generate an image of physical objects beyond the obstruction. Naturally, this was not a high-resolution capture, but the details are sufficient to identify the type of object imaged.
This technique is commendable, and it could even find use in cases such as autonomous car navigation, assisting onboard computers as they map a local environment lying just beyond line-of-sight for potential hazards, especially when the vehicle passengers cannot see it.
In other words, this technology has the potential to save lives.
But there’s a catch: so far, NLOS techniques require a large reflective surface to measure light reflections returning from a hidden object.
This new laser technique could detect danger in rooms in advance
The keyhole imaging method was created at Stanford University’s Computational Imaging Lab, and it got its name because all that is needed to see inside a closed room is a single tiny hole (like a peephole) large enough to allow a laser beam to pass through and create a single point of light on the opposite interior wall.
This latest advancement involves a laser bouncing off a wall, then off an object in the room, then off the wall again before returning through the keyhole to a camera equipped with a single-photon photodetector that can measure the time between sending and receiving the signal.
If the obstructed object is static (i.e. not moving), the new technique lacks sufficient information to identify it. To get around this, researchers discovered that they can image a moving object using laser pulses capable of generating enough viable data over a longer exposure time to provide enough information for an algorithm to build an image of the object.
Unfortunately, this technique produced images with even lower quality than previous NLOS techniques, but there is still enough detail for users to guess the shape and size of the obstructed object.
A wooden mannequin, for example, may appear to be a haunted angel, but when combined with a fully-trained image recognition AI, it isn’t difficult to conclude that the novel contraption is detecting a human-shaped object.
This will most likely be used by the police or the military in the future to assess the risks of entering a room peacefully versus storming in with guns blazing using nothing more than a bullethole or structural defect in the wall or window.
NLOS techniques could also be used to protect drones like Boston Dynamics’ Spot the robot dog while surveying dangerous terrain or searching a home for potentially armed suspects. This is an exciting technological advancement, but whether it is good or bad depends on who uses it and why.