75,148 research outputs found
Probabilistic Human Mesh Recovery in 3D Scenes from Egocentric Views
Automatic perception of human behaviors during social interactions is crucial
for AR/VR applications, and an essential component is estimation of plausible
3D human pose and shape of our social partners from the egocentric view. One of
the biggest challenges of this task is severe body truncation due to close
social distances in egocentric scenarios, which brings large pose ambiguities
for unseen body parts. To tackle this challenge, we propose a novel
scene-conditioned diffusion method to model the body pose distribution.
Conditioned on the 3D scene geometry, the diffusion model generates bodies in
plausible human-scene interactions, with the sampling guided by a physics-based
collision score to further resolve human-scene inter-penetrations. The
classifier-free training enables flexible sampling with different conditions
and enhanced diversity. A visibility-aware graph convolution model guided by
per-joint visibility serves as the diffusion denoiser to incorporate
inter-joint dependencies and per-body-part control. Extensive evaluations show
that our method generates bodies in plausible interactions with 3D scenes,
achieving both superior accuracy for visible joints and diversity for invisible
body parts. The code is available at
https://sanweiliti.github.io/egohmr/egohmr.html.Comment: Camera ready version for ICCV 2023, appendix include
Hybrid Scene Compression for Visual Localization
Localizing an image wrt. a 3D scene model represents a core task for many
computer vision applications. An increasing number of real-world applications
of visual localization on mobile devices, e.g., Augmented Reality or autonomous
robots such as drones or self-driving cars, demand localization approaches to
minimize storage and bandwidth requirements. Compressing the 3D models used for
localization thus becomes a practical necessity. In this work, we introduce a
new hybrid compression algorithm that uses a given memory limit in a more
effective way. Rather than treating all 3D points equally, it represents a
small set of points with full appearance information and an additional, larger
set of points with compressed information. This enables our approach to obtain
a more complete scene representation without increasing the memory
requirements, leading to a superior performance compared to previous
compression schemes. As part of our contribution, we show how to handle
ambiguous matches arising from point compression during RANSAC. Besides
outperforming previous compression techniques in terms of pose accuracy under
the same memory constraints, our compression scheme itself is also more
efficient. Furthermore, the localization rates and accuracy obtained with our
approach are comparable to state-of-the-art feature-based methods, while using
a small fraction of the memory.Comment: Published at CVPR 201
Starlight Demonstration of the Dragonfly Instrument: an Integrated Photonic Pupil Remapping Interferometer for High Contrast Imaging
In the two decades since the first extra-solar planet was discovered, the
detection and characterization of extra-solar planets has become one of the key
endeavors in all of modern science. Recently direct detection techniques such
as interferometry or coronography have received growing attention because they
reveal the population of exoplanets inaccessible to Doppler or transit
techniques, and moreover they allow the faint signal from the planet itself to
be investigated. Next-generation stellar interferometers are increasingly
incorporating photonic technologies due to the increase in fidelity of the data
generated. Here, we report the design, construction and commissioning of a new
high contrast imager; the integrated pupil-remapping interferometer; an
instrument we expect will find application in the detection of young faint
companions in the nearest star-forming regions. The laboratory characterisation
of the instrument demonstrated high visibility fringes on all interferometer
baselines in addition to stable closure phase signals. We also report the first
successful on-sky experiments with the prototype instrument at the 3.9-m
Anglo-Australian Telescope. Performance metrics recovered were consistent with
ideal device behaviour after accounting for expected levels of decoherence and
signal loss from the uncompensated seeing. The prospect of complete
Fourier-coverage coupled with the current performance metrics means that this
photonically-enhanced instrument is well positioned to contribute to the
science of high contrast companions.Comment: 10 pages, 7 figures, accepted to Mon. Not. of Roy. Ast. Soc., 201
Sparsity Invariant CNNs
In this paper, we consider convolutional neural networks operating on sparse
inputs with an application to depth upsampling from sparse laser scan data.
First, we show that traditional convolutional networks perform poorly when
applied to sparse data even when the location of missing data is provided to
the network. To overcome this problem, we propose a simple yet effective sparse
convolution layer which explicitly considers the location of missing data
during the convolution operation. We demonstrate the benefits of the proposed
network architecture in synthetic and real experiments with respect to various
baseline approaches. Compared to dense baselines, the proposed sparse
convolution network generalizes well to novel datasets and is invariant to the
level of sparsity in the data. For our evaluation, we derive a novel dataset
from the KITTI benchmark, comprising 93k depth annotated RGB images. Our
dataset allows for training and evaluating depth upsampling and depth
prediction techniques in challenging real-world settings and will be made
available upon publication
Integrated AlGaAs source of highly indistinguishable and energy-time entangled photons
The generation of nonclassical states of light in miniature chips is a
crucial step towards practical implementations of future quantum technologies.
Semiconductor materials are ideal to achieve extremely compact and massively
parallel systems and several platforms are currently under development. In this
context, spontaneous parametric down conversion in AlGaAs devices combines the
advantages of room temperature operation, possibility of electrical injection
and emission in the telecom band. Here we report on a chip-based AlGaAs source,
producing indistinguishable and energy-time entangled photons with a brightness
of pairs/s and a signal-to-noise ratio of .
Indistinguishability between the photons is demonstrated via a Hong-Ou-Mandel
experiment with a visibility of , while energy-time entanglement is
tested via a Franson interferometer leading to a value for the Bell parameter
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