77 research outputs found
Learning 3D Shape Completion under Weak Supervision
We address the problem of 3D shape completion from sparse and noisy point
clouds, a fundamental problem in computer vision and robotics. Recent
approaches are either data-driven or learning-based: Data-driven approaches
rely on a shape model whose parameters are optimized to fit the observations;
Learning-based approaches, in contrast, avoid the expensive optimization step
by learning to directly predict complete shapes from incomplete observations in
a fully-supervised setting. However, full supervision is often not available in
practice. In this work, we propose a weakly-supervised learning-based approach
to 3D shape completion which neither requires slow optimization nor direct
supervision. While we also learn a shape prior on synthetic data, we amortize,
i.e., learn, maximum likelihood fitting using deep neural networks resulting in
efficient shape completion without sacrificing accuracy. On synthetic
benchmarks based on ShapeNet and ModelNet as well as on real robotics data from
KITTI and Kinect, we demonstrate that the proposed amortized maximum likelihood
approach is able to compete with recent fully supervised baselines and
outperforms data-driven approaches, while requiring less supervision and being
significantly faster
Выбор способа хранения результатов научных экспериментов в базе данных на примере MS SQL Server
This article describes the use of MS SQL server as file storage to store files of scientific researches. The article describes the advantages and disadvantages of different methods of storing files to MS SQL Server
Synthesis of Frame Field-Aligned Multi-Laminar Structures
In the field of topology optimization, the homogenization approach has been
revived as an important alternative to the established, density-based methods
because it can represent the microstructural design at a much finer
length-scale than the computational grid. The optimal microstructure for a
single load case is an orthogonal rank-3 laminate. A rank-3 laminate can be
described in terms of frame fields, which are also an important tool for mesh
generation in both 2D and 3D.
We propose a method for generating multi-laminar structures from frame
fields. Rather than relying on integrative approaches that find a
parametrization based on the frame field, we find stream surfaces, represented
as point clouds aligned with frame vectors, and we solve an optimization
problem to find well-spaced collections of such stream surfaces. The stream
surface tracing is unaffected by the presence of singularities outside the
region of interest. Neither stream surface tracing nor selecting well-spaced
surface rely on combed frame fields.
In addition to stream surface tracing and selection, we provide two methods
for generating structures from stream surface collections. One of these methods
produces volumetric solids by summing basis functions associated with each
point of the stream surface collection. The other method reinterprets point
sampled stream surfaces as a spatial twist continuum and produces a
hexahedralization by dualizing a graph representing the structure.
We demonstrate our methods on several frame fields produced using the
homogenization approach for topology optimization, boundary-aligned, algebraic
frame fields, and frame fields computed from closed-form expressions.Comment: 19 pages, 18 figure
Measurement of the cosmic ray spectrum above eV using inclined events detected with the Pierre Auger Observatory
A measurement of the cosmic-ray spectrum for energies exceeding
eV is presented, which is based on the analysis of showers
with zenith angles greater than detected with the Pierre Auger
Observatory between 1 January 2004 and 31 December 2013. The measured spectrum
confirms a flux suppression at the highest energies. Above
eV, the "ankle", the flux can be described by a power law with
index followed by
a smooth suppression region. For the energy () at which the
spectral flux has fallen to one-half of its extrapolated value in the absence
of suppression, we find
eV.Comment: Replaced with published version. Added journal reference and DO
Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory
The Auger Engineering Radio Array (AERA) is part of the Pierre Auger
Observatory and is used to detect the radio emission of cosmic-ray air showers.
These observations are compared to the data of the surface detector stations of
the Observatory, which provide well-calibrated information on the cosmic-ray
energies and arrival directions. The response of the radio stations in the 30
to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of
the incoming electric field. For the latter, the energy deposit per area is
determined from the radio pulses at each observer position and is interpolated
using a two-dimensional function that takes into account signal asymmetries due
to interference between the geomagnetic and charge-excess emission components.
The spatial integral over the signal distribution gives a direct measurement of
the energy transferred from the primary cosmic ray into radio emission in the
AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air
shower arriving perpendicularly to the geomagnetic field. This radiation energy
-- corrected for geometrical effects -- is used as a cosmic-ray energy
estimator. Performing an absolute energy calibration against the
surface-detector information, we observe that this radio-energy estimator
scales quadratically with the cosmic-ray energy as expected for coherent
emission. We find an energy resolution of the radio reconstruction of 22% for
the data set and 17% for a high-quality subset containing only events with at
least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO
Measurement of the Radiation Energy in the Radio Signal of Extensive Air Showers as a Universal Estimator of Cosmic-Ray Energy
We measure the energy emitted by extensive air showers in the form of radio
emission in the frequency range from 30 to 80 MHz. Exploiting the accurate
energy scale of the Pierre Auger Observatory, we obtain a radiation energy of
15.8 \pm 0.7 (stat) \pm 6.7 (sys) MeV for cosmic rays with an energy of 1 EeV
arriving perpendicularly to a geomagnetic field of 0.24 G, scaling
quadratically with the cosmic-ray energy. A comparison with predictions from
state-of-the-art first-principle calculations shows agreement with our
measurement. The radiation energy provides direct access to the calorimetric
energy in the electromagnetic cascade of extensive air showers. Comparison with
our result thus allows the direct calibration of any cosmic-ray radio detector
against the well-established energy scale of the Pierre Auger Observatory.Comment: Replaced with published version. Added journal reference and DOI.
Supplemental material in the ancillary file
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