Polarimetric iToF: Measuring High-Fidelity Depth through Scattering
  Media
Daniel S. Jeon Andreas Meuleman Seung-Hwan Baek Min H. Kim
Indirect time-of-flight (iToF) imaging allows us to capture dense depth
information at a low cost. However, iToF imaging often suffers from multipath
interference (MPI) artifacts in the presence of scattering media, resulting in
severe depth-accuracy degradation. For instance, iToF cameras cannot measure
depth accurately through fog because ToF active illumination scatters back to
the sensor before reaching the farther target surface. In this work, we propose
a polarimetric iToF imaging method that can capture depth information robustly
through scattering media. Our observations on the principle of indirect ToF
imaging and polarization of light allow us to formulate a novel computational
model of scattering-aware polarimetric phase measurements that enables us to
correct MPI errors. We first devise a scattering-aware polarimetric iToF model
that can estimate the phase of unpolarized backscattered light. We then combine
the optical filtering of polarization and our computational modeling of
unpolarized backscattered light via scattering analysis of phase and amplitude.
This allows us to tackle the MPI problem by estimating the scattering energy
through the participating media. We validate our method on an experimental
setup using a customized off-the-shelf iToF camera. Our method outperforms
baseline methods by a significant margin by means of our scattering model and
polarimetric phase measurements.