Reconstruction of hidden 3D shapes using diffuse reflections

TL;DR

This paper presents a novel method for reconstructing hidden 3D shapes by analyzing diffuse light reflections, utilizing a backpropagation approach and specialized approximations to invert multi-bounce light propagation.

Contribution

It introduces a new theoretical framework for inverse light scattering in hidden scenes and demonstrates practical reconstruction using standard high-speed cameras.

Findings

Successful 3D shape recovery around corners

Theoretical analysis of invertibility and uniqueness

Effective use of a 2D streak camera for hidden geometry reconstruction

Abstract

We analyze multi-bounce propagation of light in an unknown hidden volume and demonstrate that the reflected light contains sufficient information to recover the 3D structure of the hidden scene. We formulate the forward and inverse theory of secondary and tertiary scattering reflection using ideas from energy front propagation and tomography. We show that using careful choice of approximations, such as Fresnel approximation, greatly simplifies this problem and the inversion can be achieved via a backpropagation process. We provide a theoretical analysis of the invertibility, uniqueness and choices of space-time-angle dimensions using synthetic examples. We show that a 2D streak camera can be used to discover and reconstruct hidden geometry. Using a 1D high speed time of flight camera, we show that our method can be used recover 3D shapes of objects "around the corner".