58,485 research outputs found
Vid2Game: Controllable Characters Extracted from Real-World Videos
We are given a video of a person performing a certain activity, from which we
extract a controllable model. The model generates novel image sequences of that
person, according to arbitrary user-defined control signals, typically marking
the displacement of the moving body. The generated video can have an arbitrary
background, and effectively capture both the dynamics and appearance of the
person.
The method is based on two networks. The first network maps a current pose,
and a single-instance control signal to the next pose. The second network maps
the current pose, the new pose, and a given background, to an output frame.
Both networks include multiple novelties that enable high-quality performance.
This is demonstrated on multiple characters extracted from various videos of
dancers and athletes
Physics-based Scene-level Reasoning for Object Pose Estimation in Clutter
This paper focuses on vision-based pose estimation for multiple rigid objects
placed in clutter, especially in cases involving occlusions and objects resting
on each other. Progress has been achieved recently in object recognition given
advancements in deep learning. Nevertheless, such tools typically require a
large amount of training data and significant manual effort to label objects.
This limits their applicability in robotics, where solutions must scale to a
large number of objects and variety of conditions. Moreover, the combinatorial
nature of the scenes that could arise from the placement of multiple objects is
hard to capture in the training dataset. Thus, the learned models might not
produce the desired level of precision required for tasks, such as robotic
manipulation. This work proposes an autonomous process for pose estimation that
spans from data generation to scene-level reasoning and self-learning. In
particular, the proposed framework first generates a labeled dataset for
training a Convolutional Neural Network (CNN) for object detection in clutter.
These detections are used to guide a scene-level optimization process, which
considers the interactions between the different objects present in the clutter
to output pose estimates of high precision. Furthermore, confident estimates
are used to label online real images from multiple views and re-train the
process in a self-learning pipeline. Experimental results indicate that this
process is quickly able to identify in cluttered scenes physically-consistent
object poses that are more precise than the ones found by reasoning over
individual instances of objects. Furthermore, the quality of pose estimates
increases over time given the self-learning process.Comment: 18 pages, 13 figures, International Journal of Robotics Research
(IJRR) 2019. arXiv admin note: text overlap with arXiv:1710.0857
The Normal Map Based on Area-Preserving Parameterization
In this paper, we present an approach to enhance and improve the current
normal map rendering technique. Our algorithm is based on semi-discrete Optimal
Mass Transportation (OMT) theory and has a solid theoretical base. The key
difference from previous normal map method is that we preserve the local area
when we unwrap a disk-like 3D surface onto 2D plane. Compared to the currently
used techniques which is based on conformal parameterization, our method does
not need to cut a surface into many small pieces to avoid the large area
distortion. The following charts packing step is also unnecessary in our
framework. Our method is practical and makes the normal map technique more
robust and efficient.Comment: we need update i
Impedance control of a cable-driven SEA with mixed synthesis
Purpose: This paper presents an impedance control method with mixed
synthesis and relaxed passivity for a cable-driven series
elastic actuator to be applied for physical human-robot interaction.
Design/methodology/approach: To shape the system's impedance to match a
desired dynamic model, the impedance control problem was reformulated into an
impedance matching structure. The desired competing performance requirements as
well as constraints from the physical system can be characterized with
weighting functions for respective signals. Considering the frequency
properties of human movements, the passivity constraint for stable human-robot
interaction, which is required on the entire frequency spectrum and may bring
conservative solutions, has been relaxed in such a way that it only restrains
the low frequency band. Thus, impedance control became a mixed
synthesis problem, and a dynamic output feedback controller can be obtained.
Findings: The proposed impedance control strategy has been tested for various
desired impedance with both simulation and experiments on the cable-driven
series elastic actuator platform. The actual interaction torque tracked well
the desired torque within the desired norm bounds, and the control input was
regulated below the motor velocity limit. The closed loop system can guarantee
relaxed passivity at low frequency. Both simulation and experimental results
have validated the feasibility and efficacy of the proposed method.
Originality/value: This impedance control strategy with mixed
synthesis and relaxed passivity provides a novel, effective and less
conservative method for physical human-robot interaction control.Comment: 11 pages, already published in Assembly Automatio
PhotoShape: Photorealistic Materials for Large-Scale Shape Collections
Existing online 3D shape repositories contain thousands of 3D models but lack
photorealistic appearance. We present an approach to automatically assign
high-quality, realistic appearance models to large scale 3D shape collections.
The key idea is to jointly leverage three types of online data -- shape
collections, material collections, and photo collections, using the photos as
reference to guide assignment of materials to shapes. By generating a large
number of synthetic renderings, we train a convolutional neural network to
classify materials in real photos, and employ 3D-2D alignment techniques to
transfer materials to different parts of each shape model. Our system produces
photorealistic, relightable, 3D shapes (PhotoShapes).Comment: To be presented at SIGGRAPH Asia 2018. Project page:
https://keunhong.com/publications/photoshape
Learning High Dynamic Range from Outdoor Panoramas
Outdoor lighting has extremely high dynamic range. This makes the process of
capturing outdoor environment maps notoriously challenging since special
equipment must be used. In this work, we propose an alternative approach. We
first capture lighting with a regular, LDR omnidirectional camera, and aim to
recover the HDR after the fact via a novel, learning-based inverse tonemapping
method. We propose a deep autoencoder framework which regresses linear, high
dynamic range data from non-linear, saturated, low dynamic range panoramas. We
validate our method through a wide set of experiments on synthetic data, as
well as on a novel dataset of real photographs with ground truth. Our approach
finds applications in a variety of settings, ranging from outdoor light capture
to image matching.Comment: 8 pages + 2 pages of citations, 10 figures. Accepted as an oral paper
at ICCV 201
Toward Standardized Classification of Foveated Displays
Emergent in the field of head mounted display design is a desire to leverage
the limitations of the human visual system to reduce the computation,
communication, and display workload in power and form-factor constrained
systems. Fundamental to this reduced workload is the ability to match display
resolution to the acuity of the human visual system, along with a resulting
need to follow the gaze of the eye as it moves, a process referred to as
foveation. A display that moves its content along with the eye may be called a
Foveated Display, though this term is also commonly used to describe displays
with non-uniform resolution that attempt to mimic human visual acuity. We
therefore recommend a definition for the term Foveated Display that accepts
both of these interpretations. Furthermore, we include a simplified model for
human visual Acuity Distribution Functions (ADFs) at various levels of visual
acuity, across wide fields of view and propose comparison of this ADF with the
Resolution Distribution Function of a foveated display for evaluation of its
resolution at a particular gaze direction. We also provide a taxonomy to allow
the field to meaningfully compare and contrast various aspects of foveated
displays in a display and optical technology-agnostic manner.Comment: 9 pages, 8 figures, presented at IEEE VR 202
Isospin symmetry breaking
We discuss the separation of isospin-symmetric and isospin-breaking
contributions in the hadronic observables within the framework of QCD plus QED.
Further, we briefly review some recent work on the low-energy hadron
phenomenology, in which the isospin-breaking effect plays a prominent role.Comment: Plenary talk at Sixth International Workshop on Chiral Dynamics, 6-10
July 2009, Bern (Switzerland
Computational Parquetry: Fabricated Style Transfer with Wood Pixels
Parquetry is the art and craft of decorating a surface with a pattern of
differently colored veneers of wood, stone or other materials. Traditionally,
the process of designing and making parquetry has been driven by color, using
the texture found in real wood only for stylization or as a decorative effect.
Here, we introduce a computational pipeline that draws from the rich natural
structure of strongly textured real-world veneers as a source of detail in
order to approximate a target image as faithfully as possible using a
manageable number of parts. This challenge is closely related to the
established problems of patch-based image synthesis and stylization in some
ways, but fundamentally different in others. Most importantly, the limited
availability of resources (any piece of wood can only be used once) turns the
relatively simple problem of finding the right piece for the target location
into the combinatorial problem of finding optimal parts while avoiding resource
collisions. We introduce an algorithm that allows to efficiently solve an
approximation to the problem. It further addresses challenges like gamut
mapping, feature characterization and the search for fabricable cuts. We
demonstrate the effectiveness of the system by fabricating a selection of
"photo-realistic" pieces of parquetry from different kinds of unstained wood
veneer
Strongly First-Order Electroweak Phase Transition and Classical Scale Invariance
In this work, we examine the possibility of realizing a strongly first-order
electroweak phase transition within the minimal classically scale invariant
extension of the standard model (SM), previously proposed and analyzed as a
potential solution to the hierarchy problem. By introducing one complex singlet
scalar and three right-handed Majorana neutrinos, the scenario was successfully
capable of achieving a radiative breaking of the electroweak symmetry
(Coleman-Weinberg Mechanism), inducing non-zero masses for the SM neutrinos
(seesaw mechanism), presenting a pseudoscalar dark matter candidate, and
predicting the existence of a second -even boson in addition to the 125 GeV
scalar. We construct the full finite-temperature one-loop effective potential
of the model, including the resummed thermal daisy loops, and demonstrate that
finite-temperature effects induce a first-order electroweak phase transition.
Requiring the thermally-driven first-order phase transition to be sufficiently
strong further constrains the model's parameter space; in particular, an
fraction of the dark matter in the universe may be
simultaneously accommodated with a strongly first-order electroweak phase
transition. Moreover, such a phase transition disfavors right-handed Majorana
neutrino masses above several hundreds of GeV, confines the pseudoscalar dark
matter masses to -2 TeV, predicts the mass of the second -even
scalar to be -300 GeV, and requires the mixing angle between the
-even components of the SM doublet and the complex singlet to lie within
the range . The obtained results are
displayed in comprehensive exclusion plots, identifying the viable regions of
the parameter space. Many of these predictions lie within the reach of the next
LHC run.Comment: 18 pages, 9 figures. Published version, typos corrected, references
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