6,261 research outputs found
Mosaics from arbitrary stereo video sequences
lthough mosaics are well established as a compact and non-redundant representation of image sequences, their application still suffers from restrictions of the camera motion or has to deal with parallax errors. We present an approach that allows construction of mosaics from arbitrary motion of a head-mounted camera pair. As there are no parallax errors when creating mosaics from planar objects, our approach first decomposes the scene into planar sub-scenes from stereo vision and creates a mosaic for each plane individually. The power of the presented mosaicing technique is evaluated in an office scenario, including the analysis of the parallax error
Constructing a WISE High Resolution Galaxy Atlas
After eight months of continuous observations, the Wide-field Infrared Survey
Explorer (WISE) mapped the entire sky at 3.4 {\mu}m, 4.6 {\mu}m, 12 {\mu}m and
22 {\mu}m. We have begun a dedicated WISE High Resolution Galaxy Atlas (WHRGA)
project to fully characterize large, nearby galaxies and produce a legacy image
atlas and source catalogue. Here we summarize the deconvolution technique used
to significantly improve the spatial resolution of WISE imaging, specifically
designed to study the internal anatomy of nearby galaxies. As a case study, we
present results for the galaxy NGC 1566, comparing the WISE super-resolution
image processing to that of Spitzer, GALEX and ground-based imaging. The is the
first paper in a two part series; results for a much larger sample of nearby
galaxies is presented in the second paper.Comment: Published in the AJ (2012, AJ, 144, 68
A Geometrically Supported Candidate Multiply-Imaged by the Hubble Frontier Fields Cluster Abell 2744
The deflection angles of lensed sources increase with their distance behind a
given lens. We utilize this geometric effect to corroborate the
photometric redshift estimate of a faint near-IR dropout,
triply-imaged by the massive galaxy cluster Abell 2744 in deep Hubble Frontier
Fields images. The multiple images of this source follow the same symmetry as
other nearby sets of multiple images which bracket the critical curves and have
well defined redshifts (up to ), but with larger deflection
angles, indicating that this source must lie at a higher redshift. Similarly,
our different parametric and non-parametric lens models all require this object
be at , with at least 95\% confidence, thoroughly excluding the
possibility of lower-redshift interlopers. To study the properties of this
source we correct the two brighter images for their magnifications, leading to
a SFR of /yr, a stellar mass of , and an age of Myr (95\% confidence). The intrinsic
apparent magnitude is 29.9 AB (F160W), and the rest-frame UV ()
absolute magnitude is . This corresponds to (, adopting ), making
this candidate one of the least luminous galaxies discovered at .Comment: 7 pages, 4 figures, 1 table; V2: very minor changes, ApJ Letters
Accepte
Visible spectrum extended-focus optical coherence microscopy for label-free sub-cellular tomography
We present a novel extended-focus optical coherence microscope (OCM)
attaining 0.7 {\mu}m axial and 0.4 {\mu}m lateral resolution maintained over a
depth of 40 {\mu}m, while preserving the advantages of Fourier domain OCM. Our
method uses an ultra-broad spectrum from a super- continuum laser source. As
the spectrum spans from near-infrared to visible wavelengths (240 nm in
bandwidth), we call the method visOCM. The combination of such a broad spectrum
with a high-NA objective creates an almost isotropic 3D submicron resolution.
We analyze the imaging performance of visOCM on microbead samples and
demonstrate its image quality on cell cultures and ex-vivo mouse brain tissue.Comment: 15 pages, 7 figure
Capturing Panoramic Depth Images with a Single Standard Camera
In this paper we present a panoramic depth imaging system. The system is mosaic-based which means that we use a single rotating camera and assemble the captured images in a mosaic. Due to a setoff of the cameraâs optical center from the rotational center of the system we are able to capture the motion parallax effect which enables the stereo reconstruction. The camera is rotating on a circular path with the step deïŹned by an angle equivalent to one column of the captured image. The equation for depth estimation can be easily extracted from system geometry. To ïŹnd the corresponding points on a stereo pair of panoramic images the epipolar geometry needs to be determined. It can be shown that the epipolar geometry is very simple if we are doing the reconstruction based on a symmetric pair of stereo panoramic images. We get a symmetric pair of stereo panoramic images when we take symmetric columns on the left and on the right side from the captured image center column. Epipolar lines of the symmetrical pair of panoramic images are image rows. We focused mainly on the system analysis. The system performs well in the reconstruction of small indoor spaces
Studying the ICM in clusters of galaxies via surface brightness fluctuations of the cosmic X-ray background
We study the surface brightness fluctuations of the cosmic X-ray background
(CXB) using Chandra data of XBOOTES. After masking out resolved sources we
compute the power spectrum of fluctuations of the unresolved CXB for angular
scales from ~2 arcsec to ~3 deg. The non-trivial large-scale structure (LSS)
signal dominates over the shot-noise of unresolved point sources at all scales
above ~1 arcmin and is produced mainly by the intracluster medium (ICM) of
unresolved clusters and groups of galaxies, as shown in our previous
publication.
The shot-noise-subtracted power spectrum of CXB fluctuations has a power-law
shape with the slope of . Its energy spectrum is well
described by the redshifted emission spectrum of optically-thin plasma with the
best-fit temperature of keV and the best-fit redshift of . They are in good agreement with theoretical expectations based
on the X-ray luminosity function and scaling relations of clusters. From these
values we estimate the typical mass and luminosity of the objects responsible
for CXB fluctuations, and
erg/s. On the other hand, the
flux-weighted mean temperature and redshift of resolved clusters are keV and , confirming that fluctuations of unresolved CXB
are caused by cooler (i.e. less massive) and more distant clusters, as
expected. We show that the power spectrum shape is sensitive to the ICM
structure all the way to the outskirts, out to .
We also look for possible contribution of the warm-hot intergalactic medium
(WHIM) to the observed CXB fluctuations.
Our results underline the significant diagnostics potential of the CXB
fluctuation analysis in studying the ICM structure in clusters.Comment: Submitted to MNRAS. Comments welcome! (19 pages, 26 figures
Faint InfraRed Extragalactic Survey: Data and Source Catalogue of the MS1054-03 field
We present deep near-infrared Js, H, and Ks band imaging of a field around
MS1054-03, a massive cluster at z=0.83. The observations were carried out with
ISAAC at the ESO VLT as part of the Faint InfraRed Extragalactic Survey
(FIRES). The total integration time amounts to 25.9h in Js, 24.4h in H, and
26.5h in Ks, divided nearly equally between four pointings covering 5.5'x5.3'.
The 3-sigma total limiting AB magnitudes for point sources from the shallowest
to deepest pointing are Js=26.0-26.2, H=25.5-25.8, and Ks=25.3-25.7. The
effective spatial resolution of the coadded images has FWHM=0.48", 0.46", and
0.52" in Js, H, and Ks. We complemented the ISAAC data with deep optical
imaging using existing HST WFPC2 mosaics in the F606W and F814W filters and new
U, B and V band data from VLT FORS1. We constructed a Ks-band limited
multicolour source catalogue to Ks(total,AB)=25 (about 5-sigma for point
sources). The catalogue contains 1858 objects, of which 1663 have eight-band
photometry. We describe the observations, data reduction, source detection and
photometric measurements method. We present the number counts, colour
distributions, and photometric redshifts z_ph of the catalogue sources. We find
that our counts at the faint end 22<Ks(AB)<25, with slope dlog(N)/dm=0.20, lie
at the flatter end of published counts in other deep fields and are consistent
with those we derived in the HDF-South, the other FIRES field. Spectroscopic
redshifts z_sp are available for about 330 sources in the MS1054-03 field;
comparison between the z_ph and z_sp shows very good agreement, with
=0.078. The MS1054-03 field observations complement our
HDF-South data set with nearly five times larger area at about 0.7 brighter
magnitudes. [ABRIDGED]Comment: Accepted for publication in the Astronomical Journal. 32 pages, 14
b/w figures, 1 color figur
Imaging of the Stellar Population of IC10 with Laser Guide Star Adaptive Optics and the Hubble Space Telescope
We present adaptive optics (AO) images of the central starburst region of the
dwarf irregular galaxy IC10. The Keck 2 telescope laser guide star was used to
achieve near diffraction-limited performance at H and K' (Strehls of 18% and
32%, respectively). The images are centered on the putative Wolf-Rayet (W-R)
object [MAC92]24. We combine our AO images with F814W data from HST. By
comparing the K' vs. [F814W]-K' color-magnitude diagram (CMD) with theoretical
isochrones, we find that the stellar population is best represented by at least
two bursts of star formation, one ~ 10 Myr ago and one much older (150-500
Myr). Young, blue stars are concentrated in the vicinity of [MAC92]24. This
population represents an OB association with a half-light radius of about 3 pc.
We resolve the W-R object [MAC92]24 into at least six blue stars. Four of these
components have near-IR colors and luminosities that make them robust WN star
candidates. By matching the location of C-stars in the CMD with those in the
SMC we derive a distance modulus for IC10 of about 24.5 mag. and a foreground
reddening of E(B-V) = 0.95. We find a more precise distance by locating the tip
of the giant branch in the F814W, H, and K' luminosity functions. We find a
weighted mean distance modulus of 24.48 +/- 0.08. The systematic error in this
measurement, due to a possible difference in the properties of the RGB
populations in IC10 and the SMC, is +/- 0.16 mag.Comment: 13 pages, 13 figures, ApJ in pres
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