Recovering three-dimensional shape around a corner using ultrafast time-of-flight imaging

Abstract

The recovery of objects obscured by scattering is an important goal in imaging and has been approached by exploiting, for example, coherence properties, ballistic photons or penetrating wavelengths. Common methods use scattered light transmitted through an occluding material, although these fail if the occluder is opaque. Light is scattered not only by transmission through objects, but also by multiple reflection from diffuse surfaces in a scene. This reflected light contains information about the scene that becomes mixed by the diffuse reflections before reaching the image sensor. This mixing is difficult to decode using traditional cameras. Here we report the combination of a time-of-flight technique and computational reconstruction algorithms to untangle image information mixed by diffuse reflection. We demonstrate a three-dimensional range camera able to look around a corner using diffusely reflected light that achieves sub-millimetre depth precision and centimetre lateral precision over 40 cm× 40 cm×40 cm of hidden space.

Locating and classifying fluorescent tags behind turbid layers using time-resolved inversion

“…Thus, the method is a two-step process: (1) record the time-resolved scattering of fluorescent markers; and (2) use prior knowledge of the scene to recover the positions of the fluorescent markers and classify them via their lifetimes. Because of the inherent wide-angle field of view of our timeresolved technique 18,19 , the method has potential use in areas such as long-range imaging through turbulence and widefield tomography using early-photon arrival times. The integration of a sparse prior here allows for recovering object information in the presence of long lifetimes.…”

“…The integration of a sparse prior here allows for recovering object information in the presence of long lifetimes. Previous methods 18,19 require the high temporal resolution and would fail to recover nanosecond emission. The suggested method does not require the fluorophore to be directly in the field of view of the camera.…”

Frequency Analysis of Transient Light Transport with Applications in Bare Sensor Imaging

“…These ultra-fast cameras have the ability to reconstruct geometry (though not its albedo) of occluded objects "around a corner" [15], acquire in-the-wild BRDFs without using encircling equipment for scenes with known geometry [16], recover an occluded target's motion using multipath analysis [17], and decompose global light transport [18]. Our analysis of light propagation in free space produces an intuitive explanation of forward light transport within all these various works, and provides the fundamental tools for developing and understanding new ultra-fast imaging applications.…”

Theoretical and experimental investigation into the influence factors for range gated reconstruction

“…Range gated has been a promising method in applications such as target detection and recognition [3], night vision [4,5], underwater [6,7], and three-dimensional (3D) imaging [8,9]. Besides, continuous development in laser, sensor, signal processing, and computer technology further improves the cost effectiveness of this approach.…”