All-photon Polarimetric Time-of-Flight Imaging

TL;DR

This paper introduces an all-photon polarimetric time-of-flight imaging technique that utilizes both first- and late-arriving photons to extract detailed scene information, including depth, normals, and material properties.

Contribution

It presents a novel temporal-polarimetric reflectance model, an efficient capture method, and a reconstruction approach that leverages all photons for enhanced scene understanding.

Findings

Enables depth, normals, and material parameter estimation from all photons.

Validated through simulation and experimental prototype.

Outperforms conventional ToF by using late-arriving photons.

Abstract

Time-of-flight (ToF) sensors provide an imaging modality fueling diverse applications, including LiDAR in autonomous driving, robotics, and augmented reality. Conventional ToF imaging methods estimate the depth by sending pulses of light into a scene and measuring the ToF of the first-arriving photons directly reflected from a scene surface without any temporal delay. As such, all photons following this first response are typically considered as unwanted noise. In this paper, we depart from the principle of using first-arriving photons and propose an all-photon ToF imaging method by incorporating the temporal-polarimetric analysis of first- and late-arriving photons, which possess rich scene information about its geometry and material. To this end, we propose a novel temporal-polarimetric reflectance model, an efficient capture method, and a reconstruction method that exploits the temporal-polarimetric changes of light reflected by the surface and sub-surface reflection. The proposed all-photon polarimetric ToF imaging method allows for acquiring depth, surface normals, and material parameters of a scene by utilizing all photons captured by the system, whereas conventional ToF imaging only obtains coarse depth from the first-arriving photons. We validate our method in simulation and experimentally with a prototype.