Keyhole Imaging: Non-Line-of-Sight Imaging and Tracking of Moving Objects Along a Single Optical Path
IEEE Transactions on Computational Imaging — 2021
Non-line-of-sight (NLOS) imaging and tracking is an emerging technology that allows the shape or position of objects around corners or behind diffusers to be recovered from transient, time-of-flight measurements. However, existing NLOS approaches require the imaging system to scan a large area on a visible surface, where the indirect light paths of hidden objects are sampled. In many applications, such as robotic vision or autonomous driving, optical access to a large scanning area may not be available, which severely limits the practicality of existing NLOS techniques. Here, we propose a new approach, dubbed keyhole imaging, that captures a sequence of transient measurements along a single optical path, for example, through a keyhole. Assuming that the hidden object of interest moves during the acquisition time, we effectively capture a series of time-resolved projections of the object’s shape from unknown viewpoints. We derive inverse methods based on expectation-maximization to recover the object’s shape and location using these measurements. Then, with the help of long exposure times and retroreflective tape, we demonstrate successful experimental results with a prototype keyhole imaging system.
@article{metzler2020keyhole,
title={Keyhole imaging: non-line-of-sight imaging and tracking of moving objects along a single optical path},
author={Metzler, Christopher A and Lindell, David B and Wetzstein, Gordon},
journal={IEEE Transactions on Computational Imaging},
volume={7},
pages={1--12},
year={2020},
publisher={IEEE}
}