Non-line-of-sight tracking of people at long range

Abstract

A remote-sensing system that can determine the position of hidden objects has applications in many critical real-life scenarios, such as search and rescue missions and safe autonomous driving. Previous work has shown the ability to range and image objects hidden from the direct line of sight, employing advanced optical imaging technologies aimed at small objects at short range. In this work we demonstrate a long-range tracking system based on single laser illumination and single-pixel single-photon detection. This enables us to track one or more people hidden from view at a stand-off distance of over 50 m. These results pave the way towards next generation LiDAR systems that will reconstruct not only the direct-view scene but also the main elements hidden behind walls or corners.

A trillion frames per second: the techniques and applications of light-in-flight photography

“…It is worth noting that in these experiments, laser powers are typically in the 0.1-1 W range. For example, the long range motion-tracking experiments where performed with 500 mW laser power [98], corresponding to ∼ 10 18 photons/second. Yet only 10 3 − 10 4 photons/second are measured in the return signal.…”

Passive optical time-of-flight for non line-of-sight localization

“…In recent years, there have been great advancements in the development of techniques that enable non-line of sight (NLOS) optical imaging for a variety of applications, ranging from microscopic imaging through scattering tissue to around-the-corner imaging [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17]. The enabling principle behind these techniques is the use of scattered light for computational reconstruction of objects that are hidden from direct view.…”

“…The enabling principle behind these techniques is the use of scattered light for computational reconstruction of objects that are hidden from direct view. This has been achieved in a variety of approaches, such as wavefront shaping [12], inverseproblem solutions based on intensity only imaging [17,18], speckle correlations [13,14], and time-resolved measurements [3,4,5,6,7,9,10]. While wavefront-shaping approaches allow diffraction-limited resolution, they require prior access to the target position or long iterative optimization procedures.…”

“…Considerably higher resolution was obtained using speckle correlations [13,14,15,16] or time-of-flight (TOF) [3,4,5,6,7,8,9,10,11] based approaches. The former rely on 'memoryeffect' angular correlations of scattered light [19], and allow diffraction-limited, single-shot passive imaging, using a simple setup.…”

Long-range depth imaging using a single-photon detector array and non-local data fusion

“…Over the past several years, single-photon sensitive detectors have been used to observe laser propagation in air [27,28], to detect objects hidden from the line-of-sight [29][30][31][32][33], and to image in the presence of scattering media [34][35][36][37][38][39][40]. In particular, progress is being made in the development and implementation of SPAD detectors in the form of dense pixel arrays [41][42][43][44].…”