28,494 research outputs found
Super-resolving multiresolution images with band-independant geometry of multispectral pixels
A new resolution enhancement method is presented for multispectral and
multi-resolution images, such as these provided by the Sentinel-2 satellites.
Starting from the highest resolution bands, band-dependent information
(reflectance) is separated from information that is common to all bands
(geometry of scene elements). This model is then applied to unmix
low-resolution bands, preserving their reflectance, while propagating
band-independent information to preserve the sub-pixel details. A reference
implementation is provided, with an application example for super-resolving
Sentinel-2 data.Comment: Source code with a ready-to-use script for super-resolving Sentinel-2
data is available at http://nicolas.brodu.net/recherche/superres
Membrane Paradigm and Horizon Thermodynamics in Lanczos-Lovelock gravity
We study the membrane paradigm for horizons in Lanczos-Lovelock models of
gravity in arbitrary D dimensions and find compact expressions for the pressure
p and viscosity coefficients \eta and \zeta of the membrane fluid. We show that
the membrane pressure is intimately connected with the Noether charge entropy
S_Wald of the horizon when we consider a specific m-th order Lanczos-Lovelock
model, through the relation pA/T=(D-2m)/(D-2)S_Wald, where T is the temperature
and A is the area of the horizon. Similarly, the viscosity coefficients are
expressible in terms of entropy and quasi-local energy associated with the
horizons. The bulk and shear viscosity coefficients are found to obey the
relation \zeta=-2(D-3)/(D-2)\eta.Comment: v1: 13 pages, no figure. (v2): refs added, typos corrected, new
subsection added on the ratio \eta/s. (v3): some clarification added, typos
corrected, to appear in JHE
Asymptotics of random Betti tables
The purpose of this paper is twofold. First, we present a conjecture to the
effect that the ranks of the syzygy modules of a smooth projective variety
become normally distributed as the positivity of the embedding line bundle
grows. Then, in an attempt to render the conjecture plausible, we prove a
result suggesting that this is in any event the typical behavior from a
probabilistic point of view. Specifically, we consider a "random" Betti table
with a fixed number of rows, sampled according to a uniform choice of
Boij-Soderberg coefficients. We compute the asymptotics of the entries as the
length of the table goes to infinity, and show that they become normally
distributed with high probability
Species and Strings
Based on well-known properties of semi-classical black holes, we show that
weakly-coupled string theory can be viewed as a theory of N = 1/g_s^2 particle
species. This statement is a string theoretic realization of the fact that the
fundamental scale in any consistent D-dimensional theory of gravity is not the
Planck length l_D, but rather the species scale L_N = N^1/(D-2) l_D. Using this
fact, we derive the bound on semi-classical black hole entropy in any
consistent theory of gravity as S > N, which when applied to string theory
provides additional evidence for the former relation. This counting also shows
that the Bekenstein-Hawking entropy can be viewed as the entanglement entropy,
without encountering any puzzle of species. We demonstrate that the counting of
species extends to the M-theory limit. The role of the species scale is now
played by the eleven-dimensional Planck length, beyond which resolution of
distances is gravitationally-impossible. The conclusion is, that string theory
is a theory of species and gets replaced by a pure gravitational theory in the
limit when species become strongly coupled and decouple.Comment: 20 page
The Right (Angled) Perspective: Improving the Understanding of Road Scenes Using Boosted Inverse Perspective Mapping
Many tasks performed by autonomous vehicles such as road marking detection,
object tracking, and path planning are simpler in bird's-eye view. Hence,
Inverse Perspective Mapping (IPM) is often applied to remove the perspective
effect from a vehicle's front-facing camera and to remap its images into a 2D
domain, resulting in a top-down view. Unfortunately, however, this leads to
unnatural blurring and stretching of objects at further distance, due to the
resolution of the camera, limiting applicability. In this paper, we present an
adversarial learning approach for generating a significantly improved IPM from
a single camera image in real time. The generated bird's-eye-view images
contain sharper features (e.g. road markings) and a more homogeneous
illumination, while (dynamic) objects are automatically removed from the scene,
thus revealing the underlying road layout in an improved fashion. We
demonstrate our framework using real-world data from the Oxford RobotCar
Dataset and show that scene understanding tasks directly benefit from our
boosted IPM approach.Comment: equal contribution of first two authors, 8 full pages, 6 figures,
accepted at IV 201
- …