A new imaging device can capture 3D scans of human faces from hundreds of metres away
Aongus McCarthy, Heriot-Watt University
From 325 metres away, your eyes can probably distinguish a person’s head from their body – and not much else. But a new laser-based device can create a three-dimensional model of their face.
Aongus McCarthy at Heriot-Watt University in Scotland and his colleagues built a device that can create detailed three-dimensional images, including ridges and indentations as small as 1 millimetre, from hundreds of metres away. It uses an imaging technique called lidar, emitting pulses of laser light that collide with objects then reflect back into the device. Based on how long each pulse takes to return, lidar can determine an object’s shape.
To get to this level of detail, the team had to carefully calibrate and align many different components, says McCarthy, such as the tiny parts that direct the laser pulses inside of the device. To enable it to distinguish single particles of light, the researchers used a light-detecting sensor based on an incredibly thin piece of superconducting wire, a component that isn’t common in lidar. Filtering out sunlight that could enter the detector and degrade the image was another challenge.
The researchers tested their lidar system on a roof near their lab by taking detailed three-dimensional images of a team member’s head from 45 and 325 metres away. On a smaller scale, they captured Lego figurines from a distance of 32 metres.
The imaging system could scan Lego characters from 32 metres away
Aongus McCarthy, Heriot-Watt University
In another test, they imaged a segment of a communication tower that was a kilometre away. “That was a very tough test – because of the bright background, and we had no control over what we could put in the scene [that we were imaging],” says McCarthy.
Feihu Xu at the University of Science and Technology of China, whose team previously used lidar for imaging from 200 kilometres away, says that McCarthy and his colleagues achieved “remarkable results” when it comes to the depth resolution of their device. “It is the best so far,” he says.
Lidar is only becoming more relevant for modern technology, says Vivek Goyal at Boston University in Massachusetts. He says that being able to create detailed three-dimensional maps of surroundings will be crucial for autonomous vehicles and even some robots – but the new device will have to be made smaller and more compact before it can be used for this purpose.
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