Using Shadows in Space-Time to See Hidden Objects

The goal of non-line-of-sight (NLOS) imaging is to image objects that lie outside the camera’s field of view. We use two-bounce light to perform NLOS imaging, a scenario in which the information about the hidden object is encoded within the cast shadows of the hidden object. When using the space-time propagation of shadows, we can estimate the 3D shape of the hidden object with just a few image captures, making the method feasible for practical applications. For example, imagine an autonomous vehicle in a tunnel being able to see ahead of the car in front of it by using two-bounce signals from the sides of the tunnel.