558,591 research outputs found
Liouville theorem, conformally invariant cones and umbilical surfaces for Grushin-type metrics
We prove a classification theorem for conformal maps with respect to the
control distance generated by a system of diagonal vector fields.
It turns out that all such maps can be obtained as compositions of suitable
dilations, inversions and isometries. We also classify all umbilical surfaces
of the underlying metric.Comment: Revised version, to appear on Israel Journal of Mathematics. New
title and added section 4 on umbilical surface
NDDepth: Normal-Distance Assisted Monocular Depth Estimation and Completion
Over the past few years, monocular depth estimation and completion have been
paid more and more attention from the computer vision community because of
their widespread applications. In this paper, we introduce novel physics
(geometry)-driven deep learning frameworks for these two tasks by assuming that
3D scenes are constituted with piece-wise planes. Instead of directly
estimating the depth map or completing the sparse depth map, we propose to
estimate the surface normal and plane-to-origin distance maps or complete the
sparse surface normal and distance maps as intermediate outputs. To this end,
we develop a normal-distance head that outputs pixel-level surface normal and
distance. Meanwhile, the surface normal and distance maps are regularized by a
developed plane-aware consistency constraint, which are then transformed into
depth maps. Furthermore, we integrate an additional depth head to strengthen
the robustness of the proposed frameworks. Extensive experiments on the
NYU-Depth-v2, KITTI and SUN RGB-D datasets demonstrate that our method exceeds
in performance prior state-of-the-art monocular depth estimation and completion
competitors. The source code will be available at
https://github.com/ShuweiShao/NDDepth.Comment: Extension of previous work arXiv:2309.1059
Mapping Exoplanets
The varied surfaces and atmospheres of planets make them interesting places
to live, explore, and study from afar. Unfortunately, the great distance to
exoplanets makes it impossible to resolve their disk with current or near-term
technology. It is still possible, however, to deduce spatial inhomogeneities in
exoplanets provided that different regions are visible at different
times---this can be due to rotation, orbital motion, and occultations by a
star, planet, or moon. Astronomers have so far constructed maps of thermal
emission and albedo for short period giant planets. These maps constrain
atmospheric dynamics and cloud patterns in exotic atmospheres. In the future,
exo-cartography could yield surface maps of terrestrial planets, hinting at the
geophysical and geochemical processes that shape them.Comment: Updated chapter for Handbook of Exoplanets, eds. Deeg & Belmonte. 17
pages, including 6 figures and 4 pages of reference
Conductance of a STM contact on the surface of a thin film
The conductance of a contact, having a radius smaller than the Fermi wave
length, on the surface of a thin metal film is investigated theoretically. It
is shown that quantization of the electron energy spectrum in the film leads to
a step-like dependence of differential conductance G(V) as a function of
applied bias eV. The distance between neighboring steps in eV equals the energy
level spacing due to size quantization. We demonstrate that a study of G(V) for
both signs of the voltage maps the spectrum of energy levels above and below
Fermi surface in scanning tunneling experiments.Comment: 15 pages, 5 figure
- …