1,189,180 research outputs found
Combining Stereo Disparity and Optical Flow for Basic Scene Flow
Scene flow is a description of real world motion in 3D that contains more
information than optical flow. Because of its complexity there exists no
applicable variant for real-time scene flow estimation in an automotive or
commercial vehicle context that is sufficiently robust and accurate. Therefore,
many applications estimate the 2D optical flow instead. In this paper, we
examine the combination of top-performing state-of-the-art optical flow and
stereo disparity algorithms in order to achieve a basic scene flow. On the
public KITTI Scene Flow Benchmark we demonstrate the reasonable accuracy of the
combination approach and show its speed in computation.Comment: Commercial Vehicle Technology Symposium (CVTS), 201
Cross Pixel Optical Flow Similarity for Self-Supervised Learning
We propose a novel method for learning convolutional neural image
representations without manual supervision. We use motion cues in the form of
optical flow, to supervise representations of static images. The obvious
approach of training a network to predict flow from a single image can be
needlessly difficult due to intrinsic ambiguities in this prediction task. We
instead propose a much simpler learning goal: embed pixels such that the
similarity between their embeddings matches that between their optical flow
vectors. At test time, the learned deep network can be used without access to
video or flow information and transferred to tasks such as image
classification, detection, and segmentation. Our method, which significantly
simplifies previous attempts at using motion for self-supervision, achieves
state-of-the-art results in self-supervision using motion cues, competitive
results for self-supervision in general, and is overall state of the art in
self-supervised pretraining for semantic image segmentation, as demonstrated on
standard benchmarks
Anisotropic flow in 4.2A GeV/c C+Ta collisions
Anisotropic flow of protons and negative pions in 4.2A GeV/c C+Ta collisions
is studied using the Fourier analysis of azimuthal distributions. The protons
exhibit pronounced directed flow. Directed flow of pions is positive in the
entire rapidity interval and indicates that the pions are preferentially
emitted in the reaction plane from the target to the projectile. The elliptic
flow of protons and negative pions is close to zero. Comparison with the
quark-gluon-string model (QGSM) and relativistic transport model (ART 1.0) show
that they both yield a flow signature similar to the experimental data.Comment: 4 pages, 3 figures, Accepted for publication in Phys. Rev.
Critical flow â towards a construction flow theory
This paper introduces the concept of Construction Physics as a more comprehensive way of understanding the construction process from a flow perspective. It establishes a preliminary definition of the term and investigates briefly the present knowledge, flow models and methods for their management. From this it argues that the state of the art does not fully cover the whole process and proposes a holistic view of the flow of all prerequisites feeding the process. It introduces the key term Critical Flow and concludes by recommending areas that should be investigated as a joint IGLC research, development and testing programme
Directed flow of neutral strange particles at AGS
Directed flow of neutral strange particles in heavy ion collisions at AGS is
studied in the ART transport model. Using a lambda mean-field potential which
is 2/3 of that for a nucleon as predicted by the constituent quark model,
lambdas are found to flow with protons but with a smaller flow parameter as
observed in experiments. For kaons, their repulsive potential, which is
calculated from the impulse approximation using the measured kaon-nucleon
scattering length, leads to a smaller anti-flow than that shown in the
preliminary E895 data. Implications of this discrepancy are discussed.Comment: 6 pages, 2 figure
Pion flow and antiflow in relativistic heavy-ion collisions
Within the framework of a relativistic transport model (ART) for heavy-ion
collisions at AGS energies, we study the transverse flow of pions with respect
to that of nucleons using two complementary approaches. It is found that in
central collisions pions develop a weak flow as a result of the flow of baryon
resonances from which they are produced. On the other hand, they have a weak
antiflow in peripheral collisions due to the shadowing of spectators.
Furthermore, it is shown that both pion flow and antiflow are dominated by
those with large transverse momenta.Comment: Phys. Rev. C, Rapid communication, in press. Figures are available
from the authors upon reques
Excitation function of nucleon and pion elliptic flow in relativistic heavy-ion collisions
Within a relativistic transport (ART) model for heavy-ion collisions, we show
that the recently observed characteristic change from out-of-plane to in-plane
elliptic flow of protons in mid-central Au+Au collisions as the incident energy
increases is consistent with the calculated results using a stiff nuclear
equation of state (K=380 MeV). We have also studied the elliptic flow of pions
and the transverse momentum dependence of both the nucleon and pion elliptic
flow in order to gain further insight about the collision dynamics.Comment: 8 pages, 2 figure
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