![]() Dual photography 5 shows one can exploit scattered light to recover two-dimensional (2D) images of objects illuminated by a structured dynamic light source and hidden from the camera. Recent methods in computer vision and inverse light transport study multiple diffuse reflections in free space. However, light that has undergone multiple diffuse reflections has diminished coherence. Other methods, like coherent LIDAR 4, exploit the coherence of light to determine the time of flight. ![]() By considering only the early ballistic photons from a sample, these methods can image through turbid media or fog 3. Line-of-sight time-of-flight information is commonly used in LIDAR (light detection and ranging) 1 and two dimensional gated viewing 2 to determine the object distance, or to reject unwanted scattered light. In conventional imaging, it is difficult to exploit this non-line-of-sight light, if the reflections or bounces are diffuse. Light from objects outside the line of sight reaches the sensor as indirect light, via multiple reflections (or bounces). The light detected on an image sensor is composed of direct light, that travels directly from the light source to an object in the line of sight of the sensor, and indirect light that interacts with other parts of the scene before striking an object in the line of sight. 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. ![]() Here we report the combination of a time-of-flight technique and computational reconstruction algorithms to untangle image information mixed by diffuse reflection. This mixing is difficult to decode using traditional cameras. This reflected light contains information about the scene that becomes mixed by the diffuse reflections before reaching the image sensor. Light is scattered not only by transmission through objects, but also by multiple reflection from diffuse surfaces in a scene. Common methods use scattered light transmitted through an occluding material, although these fail if the occluder is opaque. 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.
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