4,764 research outputs found
Creating Simplified 3D Models with High Quality Textures
This paper presents an extension to the KinectFusion algorithm which allows
creating simplified 3D models with high quality RGB textures. This is achieved
through (i) creating model textures using images from an HD RGB camera that is
calibrated with Kinect depth camera, (ii) using a modified scheme to update
model textures in an asymmetrical colour volume that contains a higher number
of voxels than that of the geometry volume, (iii) simplifying dense polygon
mesh model using quadric-based mesh decimation algorithm, and (iv) creating and
mapping 2D textures to every polygon in the output 3D model. The proposed
method is implemented in real-time by means of GPU parallel processing.
Visualization via ray casting of both geometry and colour volumes provides
users with a real-time feedback of the currently scanned 3D model. Experimental
results show that the proposed method is capable of keeping the model texture
quality even for a heavily decimated model and that, when reconstructing small
objects, photorealistic RGB textures can still be reconstructed.Comment: 2015 International Conference on Digital Image Computing: Techniques
and Applications (DICTA), Page 1 -
Random transverse-field Ising chain with long-range interactions
We study the low-energy properties of the long-range random transverse-field
Ising chain with ferromagnetic interactions decaying as a power alpha of the
distance. Using variants of the strong-disorder renormalization group method,
the critical behavior is found to be controlled by a strong-disorder fixed
point with a finite dynamical exponent z_c=alpha. Approaching the critical
point, the correlation length diverges exponentially. In the critical point,
the magnetization shows an alpha-independent logarithmic finite-size scaling
and the entanglement entropy satisfies the area law. These observations are
argued to hold for other systems with long-range interactions, even in higher
dimensions.Comment: 6 pages, 4 figure
Strong Griffiths singularities in random systems and their relation to extreme value statistics
We consider interacting many particle systems with quenched disorder having
strong Griffiths singularities, which are characterized by the dynamical
exponent, z, such as random quantum systems and exclusion processes. In several
d=1 and d=2 dimensional problems we have calculated the inverse time-scales,
t^{-1}, in finite samples of linear size, L, either exactly or numerically. In
all cases, having a discrete symmetry, the distribution function, P(t^{-1},L),
is found to depend on the variable, u=t^{-1}L^{z/d}, and to be universal given
by the limit distribution of extremes of independent and identically
distributed random numbers. This finding is explained in the framework of a
strong disorder renormalization group approach when, after fast degrees of
freedom are decimated out the system is transformed into a set of
non-interacting localized excitations. The Frechet distribution of P(t^{-1},L)
is expected to hold for all random systems having a strong disorder fixed
point, in which the Griffiths singularities are dominated by disorder
fluctuations.Comment: 11 pages, 11 figure
Benchmarking Particle Filter Algorithms for Efficient Velodyne-Based Vehicle Localization
Keeping a vehicle well-localized within a prebuilt-map is at the core of any autonomous vehicle navigation system. In this work, we show that both standard SIR sampling and rejection-based optimal sampling are suitable for efficient (10 to 20 ms) real-time pose tracking without feature detection that is using raw point clouds from a 3D LiDAR. Motivated by the large amount of information captured by these sensors, we perform a systematic statistical analysis of how many points are actually required to reach an optimal ratio between efficiency and positioning accuracy. Furthermore, initialization from adverse conditions, e.g., poor GPS signal in urban canyons, we also identify the optimal particle filter settings required to ensure convergence. Our findings include that a decimation factor between 100 and 200 on incoming point clouds provides a large savings in computational cost with a negligible loss in localization accuracy for a VLP-16 scanner. Furthermore, an initial density of âŒ2 particles/m 2 is required to achieve 100% convergence success for large-scale (âŒ100,000 m 2 ), outdoor global localization without any additional hint from GPS or magnetic field sensors. All implementations have been released as open-source software
Absence of Phase Transition for Antiferromagnetic Potts Models via the Dobrushin Uniqueness Theorem
We prove that the -state Potts antiferromagnet on a lattice of maximum
coordination number exhibits exponential decay of correlations uniformly at
all temperatures (including zero temperature) whenever . We also prove
slightly better bounds for several two-dimensional lattices: square lattice
(exponential decay for ), triangular lattice (), hexagonal
lattice (), and Kagom\'e lattice (). The proofs are based on
the Dobrushin uniqueness theorem.Comment: 32 pages including 3 figures. Self-unpacking file containing the tex
file, the needed macros (epsf.sty, indent.sty, subeqnarray.sty, and
eqsection.sty) and the 3 ps file
Critical behavior and entanglement of the random transverse-field Ising model between one and two dimensions
We consider disordered ladders of the transverse-field Ising model and study
their critical properties and entanglement entropy for varying width, , by numerical application of the strong disorder renormalization group
method. We demonstrate that the critical properties of the ladders for any
finite are controlled by the infinite disorder fixed point of the random
chain and the correction to scaling exponents contain information about the
two-dimensional model. We calculate sample dependent pseudo-critical points and
study the shift of the mean values as well as scaling of the width of the
distributions and show that both are characterized by the same exponent,
. We also study scaling of the critical magnetization, investigate
critical dynamical scaling as well as the behavior of the critical entanglement
entropy. Analyzing the -dependence of the results we have obtained accurate
estimates for the critical exponents of the two-dimensional model:
, and .Comment: 10 pages, 9 figure
Ensemble renormalization group for disordered systems
We propose and study a renormalization group transformation that can be used
also for models with strong quenched disorder, like spin glasses. The method is
based on a mapping between disorder distributions, chosen such as to keep some
physical properties (e.g., the ratio of correlations averaged over the
ensemble) invariant under the transformation. We validate this ensemble
renormalization group by applying it to the hierarchical model (both the
diluted ferromagnetic version and the spin glass version), finding results in
agreement with Monte Carlo simulations.Comment: 7 pages, 10 figure
Strong-randomness infinite-coupling phase in a random quantum spin chain
We study the ground-state phase diagram of the Ashkin-Teller random quantum
spin chain by means of a generalization of the strong-disorder renormalization
group. In addition to the conventional paramagnetic and ferromagnetic (Baxter)
phases, we find a partially ordered phase characterized by strong randomness
and infinite coupling between the colors. This unusual phase acts, at the same
time, as a Griffiths phase for two distinct quantum phase transitions both of
which are of infinite-randomness type. We also investigate the quantum
multi-critical point that separates the two-phase and three-phase regions; and
we discuss generalizations of our results to higher dimensions and other
systems.Comment: 9 pages, 6 eps figures, final version as publishe
Correlation amplitude and entanglement entropy in random spin chains
Using strong-disorder renormalization group, numerical exact diagonalization,
and quantum Monte Carlo methods, we revisit the random antiferromagnetic XXZ
spin-1/2 chain focusing on the long-length and ground-state behavior of the
average time-independent spin-spin correlation function C(l)=\upsilon
l^{-\eta}. In addition to the well-known universal (disorder-independent)
power-law exponent \eta=2, we find interesting universal features displayed by
the prefactor \upsilon=\upsilon_o/3, if l is odd, and \upsilon=\upsilon_e/3,
otherwise. Although \upsilon_o and \upsilon_e are nonuniversal (disorder
dependent) and distinct in magnitude, the combination \upsilon_o + \upsilon_e =
-1/4 is universal if C is computed along the symmetric (longitudinal) axis. The
origin of the nonuniversalities of the prefactors is discussed in the
renormalization-group framework where a solvable toy model is considered.
Moreover, we relate the average correlation function with the average
entanglement entropy, whose amplitude has been recently shown to be universal.
The nonuniversalities of the prefactors are shown to contribute only to surface
terms of the entropy. Finally, we discuss the experimental relevance of our
results by computing the structure factor whose scaling properties,
interestingly, depend on the correlation prefactors.Comment: v1: 16 pages, 15 figures; v2: 17 pages, improved discussions and
statistics, references added, published versio
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