64 research outputs found
Accurate Single Image Multi-Modal Camera Pose Estimation
Abstract. A well known problem in photogrammetry and computer vision is the precise and robust determination of camera poses with respect to a given 3D model. In this work we propose a novel multi-modal method for single image camera pose estimation with respect to 3D models with intensity information (e.g., LiDAR data with reflectance information). We utilize a direct point based rendering approach to generate synthetic 2D views from 3D datasets in order to bridge the dimensionality gap. The proposed method then establishes 2D/2D point and local region correspondences based on a novel self-similarity distance measure. Correct correspondences are robustly identified by searching for small regions with a similar geometric relationship of local self-similarities using a Generalized Hough Transform. After backprojection of the generated features into 3D a standard Perspective-n-Points problem is solved to yield an initial camera pose. The pose is then accurately refined using an intensity based 2D/3D registration approach. An evaluation on Vis/IR 2D and airborne and terrestrial 3D datasets shows that the proposed method is applicable to a wide range of different sensor types. In addition, the approach outperforms standard global multi-modal 2D/3D registration approaches based on Mutual Information with respect to robustness and speed. Potential applications are widespread and include for instance multispectral texturing of 3D models, SLAM applications, sensor data fusion and multi-spectral camera calibration and super-resolution applications
The AMANDA Neutrino Telescope
With an effective telescope area of order m for TeV neutrinos, a
threshold near 50 GeV and a pointing accuracy of 2.5 degrees per muon
track, the AMANDA detector represents the first of a new generation of high
energy neutrino telescopes, reaching a scale envisaged over 25 years ago. We
describe early results on the calibration of natural deep ice as a particle
detector as well as on AMANDA's performance as a neutrino telescope.Comment: 12 pages, Latex2.09, uses espcrc2.sty and epsf.sty, 13 postscript
files included. Talk presented at the 18th International Conference on
Neutrino Physics and Astrophysics (Neutrino 98), Takayama, Japan, June 199
Muon Track Reconstruction and Data Selection Techniques in AMANDA
The Antarctic Muon And Neutrino Detector Array (AMANDA) is a high-energy
neutrino telescope operating at the geographic South Pole. It is a lattice of
photo-multiplier tubes buried deep in the polar ice between 1500m and 2000m.
The primary goal of this detector is to discover astrophysical sources of high
energy neutrinos. A high-energy muon neutrino coming through the earth from the
Northern Hemisphere can be identified by the secondary muon moving upward
through the detector. The muon tracks are reconstructed with a maximum
likelihood method. It models the arrival times and amplitudes of Cherenkov
photons registered by the photo-multipliers. This paper describes the different
methods of reconstruction, which have been successfully implemented within
AMANDA. Strategies for optimizing the reconstruction performance and rejecting
background are presented. For a typical analysis procedure the direction of
tracks are reconstructed with about 2 degree accuracy.Comment: 40 pages, 16 Postscript figures, uses elsart.st
Search for Lepton-Flavor-Violating tau Decays into a Lepton and an f0(980) Meson
We search for lepton-flavor-violating tau decays into a lepton (electron or
muon) and an f0(980) meson using 671 fb-1 of data collected with the Belle
detector at the KEKB asymmetric-energy e+e- collider. No events are observed
and we set the following 90% C.L. upper limits on the branching fraction
products: B(tau- -> e-f0(980))*B(f0(980)->pi+pi-)
mu-f0(980))*B(f0(980) -> pi+pi-)<3.4x10^-8. This is the first search performed
for these modes.Comment: 10 pages, 4 figures, submitted to Phys. Lett.
A framework for analysis of linear ultrasound videos to detect fetal presentation and heartbeat.
Confirmation of pregnancy viability (presence of fetal cardiac activity) and diagnosis of fetal presentation (head or buttock in the maternal pelvis) are the first essential components of ultrasound assessment in obstetrics. The former is useful in assessing the presence of an on-going pregnancy and the latter is essential for labour management. We propose an automated framework for detection of fetal presentation and heartbeat from a predefined free-hand ultrasound sweep of the maternal abdomen. Our method exploits the presence of key anatomical sonographic image patterns in carefully designed scanning protocols to develop, for the first time, an automated framework allowing novice sonographers to detect fetal breech presentation and heartbeat from an ultrasound sweep. The framework consists of a classification regime for a frame by frame categorization of each 2D slice of the video. The classification scores are then regularized through a conditional random field model, taking into account the temporal relationship between the video frames. Subsequently, if consecutive frames of the fetal heart are detected, a kernelized linear dynamical model is used to identify whether a heartbeat can be detected in the sequence. In a dataset of 323 predefined free-hand videos, covering the mother's abdomen in a straight sweep, the fetal skull, abdomen, and heart were detected with a mean classification accuracy of 83.4%. Furthermore, for the detection of the heartbeat an overall classification accuracy of 93.1% was achieved
Observation of Ds1(2536)+ -> D+pi-K+ and angular decomposition of Ds1(2536)+ -> D*+K0S
Using 462/fb of e+e- annihilation data recorded by the Belle detector, we
report the first observation of the decay Ds1(2536)+ -> D+pi-K+. The ratio of
branching fractions B(Ds1+ -> D+pi-K+)/B(Ds1+ -> D*+K0) is measured to be
(3.27+-0.18+-0.37)%. We also study the angular distributions in the Ds1(2536)+
-> D*+K0S decay and measure the ratio of D- and S-wave amplitudes. The S-wave
dominates, with a partial width of Gamma_S/Gamma_total=0.72+-0.05+-0.01.Comment: Submitted to Phys.Rev.D 16 pages, 6 figures, 3 table
Search for \bar{B}^0\to\Lambda_c^+\bar{\Lambda}_c^- decay at Belle
We search for the doubly charmed baryonic decay
, in a data sample of
events accumulated at the resonance with the Belle
detector at the KEKB asymmetric e^+e^- collider. We find no significant signal
and set an upper limit of at 90%
confidence level. The result is significantly below a naive extrapolation from
assuming a simple Cabibbo-suppression
factor of . The small branching fraction could be attributed
to a suppression due to the large momentum of the baryonic decay products,
which has been observed in other charmed baryonic two-body B decays. trend
observed in other charmed baryonic two-body B decays.Comment: 12 page, 5 figures. Contribution paper for conferences EPS2007 and
Lepton Photon 2007, Belle-Conference-070
Sensitivity of the IceCube Detector to Astrophysical Sources of High Energy Muon Neutrinos
We present the results of a Monte-Carlo study of the sensitivity of the
planned IceCube detector to predicted fluxes of muon neutrinos at TeV to PeV
energies. A complete simulation of the detector and data analysis is used to
study the detector's capability to search for muon neutrinos from sources such
as active galaxies and gamma-ray bursts. We study the effective area and the
angular resolution of the detector as a function of muon energy and angle of
incidence. We present detailed calculations of the sensitivity of the detector
to both diffuse and pointlike neutrino emissions, including an assessment of
the sensitivity to neutrinos detected in coincidence with gamma-ray burst
observations. After three years of datataking, IceCube will have been able to
detect a point source flux of E^2*dN/dE = 7*10^-9 cm^-2s^-1GeV at a 5-sigma
significance, or, in the absence of a signal, place a 90% c.l. limit at a level
E^2*dN/dE = 2*10^-9 cm^-2s^-1GeV. A diffuse E-2 flux would be detectable at a
minimum strength of E^2*dN/dE = 1*10^-8 cm^-2s^-1sr^-1GeV. A gamma-ray burst
model following the formulation of Waxman and Bahcall would result in a 5-sigma
effect after the observation of 200 bursts in coincidence with satellite
observations of the gamma-rays.Comment: 33 pages, 13 figures, 6 table
Search for B -> h(*) nu nubar Decays at Belle
We present a search for the rare decays B -> h(*) nu nubar, where h(*) stands
for a light meson. A data sample of 535 million BBbar pairs collected with the
Belle detector at the KEKB e+e- collider is used. Signal candidates are
required to have an accompanying B meson fully reconstructed in a hadronic mode
and signal-side particles consistent with a single h(*) meson. No significant
signal is observed and we set upper limits on the branching fractions at 90%
confidence level. The limits on B0 -> K*0 nu nubar and B+ -> K+ nu nubar decays
are more stringent than the previous constraints, while the first searches for
B0 -> K0 nu nubar, pi0 nu nubar, rho0 nu nubar, phi nu nubar and B+ -> K*+ nu
nubar, rho+ nu nubar are reported.Comment: 6 pages, 2 figures, submit to PR
On the selection of AGN neutrino source candidates for a source stacking analysis with neutrino telescopes
The sensitivity of a search for sources of TeV neutrinos can be improved by
grouping potential sources together into generic classes in a procedure that is
known as source stacking. In this paper, we define catalogs of Active Galactic
Nuclei (AGN) and use them to perform a source stacking analysis. The grouping
of AGN into classes is done in two steps: first, AGN classes are defined, then,
sources to be stacked are selected assuming that a potential neutrino flux is
linearly correlated with the photon luminosity in a certain energy band (radio,
IR, optical, keV, GeV, TeV). Lacking any secure detailed knowledge on neutrino
production in AGN, this correlation is motivated by hadronic AGN models, as
briefly reviewed in this paper.
The source stacking search for neutrinos from generic AGN classes is
illustrated using the data collected by the AMANDA-II high energy neutrino
detector during the year 2000. No significant excess for any of the suggested
groups was found.Comment: 43 pages, 12 figures, accepted by Astroparticle Physic
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