Research press release


Nature Photonics

Camera sees hidden objects around corners



Genevieve GariepyとDaniele Faccioたちが設計したシステムは、2つの装置、すなわちレーザー装置と単一光子アバランシェダイオード(SPAD)カメラで構成されている。SPADカメラは、感度が高く、応答速度が非常に速い。Gariepyたちはレーザー装置から短パルス光ストリームを発射し、ちょうど角の正面にあたる床の一部に照射した。光パルスは床面で散乱された後、隠れた物体(発泡材でできた高さ30 cmの人形)にぶつかって反射されると、カメラの視野に入って(カメラも角の正面にあたる床部分の方向を向いている)、検出・解析される。このシステムは、光パルスの飛行時間とカメラが受光する光パターンの形状を利用して、物体の位置情報を得ている。

Gariepyたちはこの手法を用いて、壁の裏手に隠れた物体の位置をたった3秒の収集時間で特定できたほか、カメラから1 m離れた物体の動きをリアルタイムで確実に追跡できた。今後の研究では、物体の3D再構成が試みられる可能性があるという。

A camera system that can look around corners and sense the position of a hidden object-with centimetre precision-and then track its movement, is described in a paper published online in Nature Photonics this week. The study may pave the way for tracking hidden objects in real time in a number of real-life scenarios, including surveillance and vehicle collision avoidance systems that can see around blind corners.

The ability to detect the 3D shape of static, hidden objects has been demonstrated in recent studies. However, the long acquisition times required by existing methods means that locating the position of moving objects and monitoring their movement in real time remains a major challenge.

The system designed by Genevieve Gariepy, Daniele Faccio and colleagues comprises two pieces of equipment: a laser and a single-photon avalanche diode (SPAD) camera, which is highly sensitive and has an ultrafast response. The authors fired a stream of short pulses of light from the laser onto the floor just in front of the corner, which were then scattered by the floor and went on to hit a hidden object (a human form made of foam 30 cm high). The light pulses reflected back off the object, into the field of view of the camera (which also points at the region of the floor in front of the corner), and are then detected and analysed. The system uses the time of flight of the light pulses and shape of the pattern of light received by the camera to provide information about the object’s position.

With this technology, the authors are able to locate the position of an object hidden behind a wall with only three seconds acquisition time, and can reliably track, in real time, the movement of an object located a metre away from the camera. They note future work could attempt 3D reconstruction of the object.

doi: 10.1038/nphoton.2015.234


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