11,729 research outputs found
Fast Back-Projection for Non-Line of Sight Reconstruction
Recent works have demonstrated non-line of sight (NLOS) reconstruction by
using the time-resolved signal frommultiply scattered light. These works
combine ultrafast imaging systems with computation, which back-projects the
recorded space-time signal to build a probabilistic map of the hidden geometry.
Unfortunately, this computation is slow, becoming a bottleneck as the imaging
technology improves. In this work, we propose a new back-projection technique
for NLOS reconstruction, which is up to a thousand times faster than previous
work, with almost no quality loss. We base on the observation that the hidden
geometry probability map can be built as the intersection of the three-bounce
space-time manifolds defined by the light illuminating the hidden geometry and
the visible point receiving the scattered light from such hidden geometry. This
allows us to pose the reconstruction of the hidden geometry as the voxelization
of these space-time manifolds, which has lower theoretic complexity and is
easily implementable in the GPU. We demonstrate the efficiency and quality of
our technique compared against previous methods in both captured and synthetic
dat
Non-line-of-sight tracking of people at long range
A remote-sensing system that can determine the position of hidden objects has
applications in many critical real-life scenarios, such as search and rescue
missions and safe autonomous driving. Previous work has shown the ability to
range and image objects hidden from the direct line of sight, employing
advanced optical imaging technologies aimed at small objects at short range. In
this work we demonstrate a long-range tracking system based on single laser
illumination and single-pixel single-photon detection. This enables us to track
one or more people hidden from view at a stand-off distance of over 50~m. These
results pave the way towards next generation LiDAR systems that will
reconstruct not only the direct-view scene but also the main elements hidden
behind walls or corners
Non-line-of-sight transient rendering
The capture and analysis of light in flight, or light in transient state, has enabled applications such as range imaging, reflectance estimation and especially non-line-of-sight (NLOS) imaging. For this last case, hidden geometry can be reconstructed using time-resolved measurements of indirect diffuse light emitted by a laser. Transient rendering is a key tool for developing such new applications, significantly more challenging than its steady-state counterpart. In this work, we introduce a set of simple yet effective subpath sampling techniques targeting transient light transport simulation in occluded scenes. We analyze the usual capture setups of NLOS scenes, where both the camera and light sources are focused on particular points in the scene. Also, the hidden geometry can be difficult to sample using conventional techniques. We leverage that configuration to reduce the integration path space. We implement our techniques in a modified version of Mitsuba 2 adapted for transient light transport, allowing us to support parallelization, polarization, and differentiable rendering. © 2022 The Author(s
- …