38 research outputs found
A 3D Active Learning Application for NeMO-Net, the NASA Neural Multi-Modal Observation and Training Network for Global Coral Reef Assessment
NeMO-Net, the NASA neural multi-modal observation and training network for global coral reef assessment, is an open-source deep convolutional neural network and interactive active learning training software aiming to accurately assess the present and past dynamics of coral reef ecosystems through determination of percent living cover and morphology as well as mapping of spatial distribution. We present an interactive video game prototype for tablet and mobile devices where users interactively label morphology classifications over mm-scale 3D coral reef imagery captured using fluid lensing to create a dataset that will be used to train NeMO-Nets convolutional neural network. The application currently allows for users to classify preselected regions of coral in the Pacific and will be expanded to include additional regions captured using our NASA FluidCam instrument, presently the highest-resolution remote sensing benthic imaging technology capable of removing ocean wave distortion, as well as lower-resolution airborne remote sensing data from the ongoing NASA CORAL campaign. Active learning applications present a novel methodology for efficiently training large-scale Neural Networks wherein variances in identification can be rapidly mitigated against control data. NeMO-Net periodically checks users input against pre-classified coral imagery to gauge their accuracy and utilize in-game mechanics to provide classification training. Users actively communicate with a server and are requested to classify areas of coral for which other users had conflicting classifications and contribute their input to a larger database for ranking. In partnering with Mission Blue and IUCN, NeMO-Net leverages an international consortium of subject matter experts to classify areas of confusion identified by NeMO-Net and generate additional labels crucial for identifying decision boundary locations in coral reef assessment
NeMO-Net The Neural Multi-Modal Observation & Training Network for Global Coral Reef Assessment
We present NeMO-Net, the Srst open-source deep convolutional neural network (CNN) and interactive learning and training software aimed at assessing the present and past dynamics of coral reef ecosystems through habitat mapping into 10 biological and physical classes. Shallow marine systems, particularly coral reefs, are under significant pressures due to climate change, ocean acidification, and other anthropogenic pressures, leading to rapid, often devastating changes, in these fragile and diverse ecosystems. Historically, remote sensing of shallow marine habitats has been limited to meter-scale imagery due to the optical effects of ocean wave distortion, refraction, and optical attenuation. NeMO-Net combines 3D cm-scale distortion-free imagery captured using NASA FluidCam and Fluid lensing remote sensing technology with low resolution airborne and spaceborne datasets of varying spatial resolutions, spectral spaces, calibrations, and temporal cadence in a supercomputer-based machine learning framework. NeMO-Net augments and improves the benthic habitat classification accuracy of low-resolution datasets across large geographic ad temporal scales using high-resolution training data from FluidCam.NeMO-Net uses fully convolutional networks based upon ResNet and ReSneNet to perform semantic segmentation of remote sensing imagery of shallow marine systems captured by drones, aircraft, and satellites, including WorldView and Sentinel. Deep Laplacian Pyramid Super-Resolution Networks (LapSRN) alongside Domain Adversarial Neural Networks (DANNs) are used to reconstruct high resolution information from low resolution imagery, and to recognize domain-invariant features across datasets from multiple platforms to achieve high classification accuracies, overcoming inter-sensor spatial, spectral and temporal variations.Finally, we share our online active learning and citizen science platform, which allows users to provide interactive training data for NeMO-Net in 2D and 3D, integrated within a deep learning framework. We present results from the PaciSc Islands including Fiji, Guam and Peros Banhos 1 1 2 1 3 1 where 24-class classification accuracy exceeds 91%
NeMO-Net - The Neural Multi-Modal Observation & Training Network for Global Coral Reef Assessment
In the past decade, coral reefs worldwide have experienced unprecedented stresses due to climate change, ocean acidification, and anthropomorphic pressures, instigating massive bleaching and die-off of these fragile and diverse ecosystems. Furthermore, remote sensing of these shallow marine habitats is hindered by ocean wave distortion, refraction and optical attenuation, leading invariably to data products that are often of low resolution and signal-to-noise (SNR) ratio. However, recent advances in UAV and Fluid Lensing technology have allowed us to capture multispectral 3D imagery of these systems at sub-cm scales from above the water surface, giving us an unprecedented view of their growth and decay. By combining spatial and spectral information from varying resolutions, we seek to augment and improve the classification accuracy of previously low-resolution datasets at large temporal scales.NeMO-Net, the first open-source deep convolutional neural network (CNN) and interactive learning and training software, currently being developed at NASA Ames, is aimed at assessing the present and past dynamics of coral reef ecosystems through determination of percent living cover and morphology. The latest iteration uses fully convolutional networks to segment and identify coral imagery taken by UAVs and satellites, including WorldView-2 and Sentinel. We present results taken from the Indian Ocean where classification accuracy has exceeded 91% for 24 geomorphological classes given ample training data. In addition, we utilize deep Laplacian Pyramid Super-Resolution Networks (LapSRN) to reconstruct high resolution information from low resolution imagery, trained from various UAV and satellite datasets. Finally, in the case of insufficient training data, we have developed an interactive online platform that allows users to easily segment and submit their classifications, which has been integrated with the current NeMO-Net workflow. Specifically, we present results from the Fiji islands in which preliminary user data has allowed for the accurate identification of 9 separate classes, despite issues such as cloud shadowing and spectral variation. The project is being supported by NASA's Earth Science Technology Office (ESTO) Advanced Information Systems Technology (AIST-16) Program
Five supernova survey galaxies in the southern hemisphere. I. Optical and near-infrared database
The determination of the supernova (SN) rate is based not only on the number
of detected events, but also on the properties of the parent galaxy population.
This is the first paper of a series aimed at obtaining new, refined, SN rates
from a set of five SN surveys, by making use of a joint analysis of
near-infrared (NIR) data. We describe the properties of the 3838 galaxies that
were monitored for SNe events, including newly determined morphologies and
their DENIS and POSS-II/UKST I, 2MASS and DENIS J and Ks and 2MASS H
magnitudes. We have compared 2MASS, DENIS and POSS-II/UKST IJK magnitudes in
order to find possible systematic photometric shifts in the measurements. The
DENIS and POSS-II/UKST I band magnitudes show large discrepancies (mean
absolute difference of 0.4 mag), mostly due to different spectral responses of
the two instruments, with an important contribution (0.33 mag rms) from the
large uncertainties in the photometric calibration of the POSS-II and UKST
photographic plates. In the other wavebands, the limiting near infrared
magnitude, morphology and inclination of the galaxies are the most influential
factors which affect the determination of photometry of the galaxies.
Nevertheless, no significant systematic differences have been found between of
any pair of NIR magnitude measurements, except for a few percent of galaxies
showing large discrepancies. This allows us to combine DENIS and 2MASS data for
the J and Ks filters.Comment: 17 pages, 3 figures, 5 tables, published in Astrophysics, Vol. 52,
No. 1, 2009 (English translation of Astrofizika
The migration of nearby spirals from the blue to red sequence: AGN feedback or environmental effects?
We combine ultraviolet to near-infrared photometry with HI 21cm line
observations for a complete volume-limited sample of nearby galaxies in
different environments (from isolated galaxies to Virgo cluster members), to
study the migration of spirals from the blue to the red sequence. Although our
analysis confirms that, in the transition region between the two sequences, a
high fraction of spirals host active galactic nuclei (AGN), it clearly shows
that late-types with quenched star formation are mainly HI deficient galaxies
preferentially found in the Virgo cluster. This not only suggests that
environmental effects could play a significant role in driving the migration of
local galaxies from the blue sequence, but it also implies that a physical link
between AGN feedback and quenching may not be assumed from a correlation
between nuclear activity and colour.Comment: Accepted for publication in MNRAS. 6 pages, 1 figur
Uniting Old Stellar Systems: From Globular Clusters to Giant Ellipticals
Here we examine the relationship between the virial and stellar mass for a
range of old stellar systems, from GCs to giant ellipticals, and including such
Intermediate Mass Objects (IMOs). Improvements on previous work in this area
include the use of (i) near-infrared magnitudes from the 2MASS survey, (ii)
aperture corrections to velocity dispersions, (iii) homogeneous half light
radii and (iv) accounting for the effects of non-homology in galaxies. We find
a virial-to-stellar mass relation that ranges from ~10 M_o systems (GCs) to
~10 M_o systems (elliptical galaxies). The lack of measured velocity
dispersions for dwarf ellipticals with -16 > M_K > -18 (~10 M_o) currently
inhibits our ability to determine how, or indeed if, these galaxies connect
continuously with GCs in terms of their virial-to-stellar mass ratios. We find
elliptical galaxies to have roughly equal fractions of dark and stellar matter
within a virial radius; only in the most massive (greater than 10 M_o)
ellipticals does dark matter dominate the virial mass. Although the IMOs reveal
slightly higher virial-to-stellar mass ratios than lower mass GCs, this may
simply reflect our limited understanding of their IMF (and hence their stellar
mass-to-light ratios) or structural properties. We argue that most of these
intermediate mass objects are a natural extension of the GC sequence to higher
masses, i.e. IMOs are essentially massive star clusters. [Abridged].Comment: 15 pages, 14 figures, 1 table, submitted to MNRAS 22/5/08, Revised to
include data from Mieske etal. (0806.0374), accepted by MNRAS 22/7/08. See
http://astronomy.swin.edu.au/dforbes for full Tabl
Near-IR Atlas of S0-Sa galaxies (NIRS0S)
An atlas of Ks-band images of 206 early-type galaxies is presented, including
160 S0-S0/a galaxies, 12 ellipticals, and 33 Sa galaxies. A majority of the
Atlas galaxies belong to a magnitude-limited (mB<12.5 mag) sample of 185 NIRS0S
(Near-IR S0 galaxy Survey) galaxies. To assure that mis-classified S0s are not
omitted, 25 ellipticals from RC3 classified as S0s in the Carnegie Atlas were
included in the sample. The images are 2-3 mag deeper than 2MASS images. Both
visual and photometric classifications are made. Special attention is paid to
the classification of lenses, coded in a systematic manner. A new lens-type,
called a 'barlens', is introduced. Also, boxy/peanut/x-shaped structures are
identified in many barred galaxies, even-though the galaxies are not seen in
edge-on view, indicating that vertical thickening is not enough to explain
them. Multiple lenses appear in 25% of the Atlas galaxies, which is a challenge
to the hierarchical evolutionary picture of galaxies. Such models need to
explain how the lenses were formed and survived in multiple merger events that
galaxies may have suffered during their lifetimes. Following the early
suggestion by van den Bergh, candidates of S0c galaxies are shown, which
galaxies are expected to be former Sc-type spirals stripped out of gas.Comment: 67 pages (include 16 figures and 6 tables). Accepted to MNRAS 2011
June 1
Near-infrared bulge-disc correlations of lenticular galaxies
We consider the luminosity and environmental dependence of structural
parameters of lenticular galaxies in the near-infrared K band. Using a
two-dimensional galaxy image decomposition technique, we extract bulge and disk
structural parameters for a sample of 36 lenticular galaxies observed by us in
the K band. By combining data from the literature for field and cluster
lenticulars with our data, we study correlations between parameters that
characterise the bulge and the disk as a function of luminosity and
environment. We find that scaling relations such as the Kormendy relation,
photometric plane and other correlations involving bulge and disk parameters
show a luminosity dependence. This dependence can be explained in terms of
galaxy formation models in which faint lenticulars (M_T > -24.5) formed via
secular formation processes that likely formed the pseudobulges of late-type
disk galaxies, while brighter lenticulars (M_T < -24.5) formed through a
different formation mechanism most likely involving major mergers. On probing
variations in lenticular properties as a function of environment, we find that
faint cluster lenticulars show systematic differences with respect to faint
field lenticulars. These differences support the idea that the bulge and disk
components fade after the galaxy falls into a cluster, while simultaneously
undergoing a transformation from spiral to lenticular morphologies.Comment: Published in MNRAS; added correct Bibliographic reference; 10 pages,
2 tables and 11 figure
Evolution along the sequence of S0 Hubble types induced by dry minor mergers. I - Global bulge-to-disk structural relations
Recent studies have argued that galaxy mergers are not important drivers for
the evolution of S0's, on the basis that mergers cannot preserve the coupling
between the bulge and disk scale-lengths observed in these galaxies and the
lack of correlation of their ratio with the S0 Hubble type. We investigate
whether the remnants resulting from collision-less N-body simulations of
intermediate and minor mergers onto S0 galaxies evolve fulfilling global
structural relations observed between the bulges and disks of these galaxies.
Different initial bulge-to-disk ratios of the primary S0 have been considered,
as well as different satellite densities, mass ratios, and orbits of the
encounter. We have analysed the final morphology of the remnants in images
simulating the typical observing conditions of S0 surveys. We derive bulge+disk
decompositions of the final remnants to compare their global bulge-to-disk
structure with observations. We show that all remnants present undisturbed S0
morphologies according to the prescriptions of specialized surveys. The dry
intermediate and minor mergers induce noticeable bulge growth (S0c --> S0b and
S0b --> S0a), but affect negligibly to the bulge and disk scale-lengths.
Therefore, if a coupling between these two components exists prior to the
merger, the encounter does not break this coupling. This fact provides a simple
explanation for the lack of correlation between the ratio of bulge and disk
scale-lengths and the S0 Hubble type reported by observations. These models
prove that dry intermediate and minor mergers can induce global structural
evolution within the sequence of S0 Hubble types compatible with observations,
meaning that these processes should not be discarded from the evolutionary
scenarios of S0's just on the basis of the strong coupling observed between the
bulge and disk scale-lengths in these galaxies (abridged).Comment: Accepted for publication in Astronomy & Astrophysics, 12 pages, 11
figures. Definitive version after proofs. Corrected typo in the legend of
Fig. 2. Definitive version of Fig. 7 (pending copyright implications in the
previous version). Added references and corrected typo
The Tully-Fisher relations of early-type spiral and S0 galaxies
We demonstrate that the comparison of Tully-Fisher relations (TFRs) derived
from global HI line widths to TFRs derived from the circular velocity profiles
of dynamical models (or stellar kinematic observations corrected for asymmetric
drift) is vulnerable to systematic and uncertain biases introduced by the
different measures of rotation used. We therefore argue that to constrain the
relative locations of the TFRs of spiral and S0 galaxies, the same tracer and
measure must be used for both samples. Using detailed near-infrared imaging and
the circular velocities of axisymmetric Jeans models of 14 nearby edge-on Sa-Sb
spirals and 14 nearby edge-on S0s drawn from a range of environments, we find
that S0s lie on a TFR with the same slope as the spirals, but are on average
0.53+/-0.15 mag fainter at Ks-band at a given rotational velocity. This is a
significantly smaller offset than that measured in earlier studies of the S0
TFR, which we attribute to our elimination of the bias associated with using
different rotation measures and our use of earlier type spirals as a reference.
Since our measurement of the offset avoids systematic biases, it should be
preferred to previous estimates. A spiral stellar population in which star
formation is truncated would take ~1 Gyr to fade by 0.53 mag at Ks-band. If S0s
are the products of a simple truncation of star formation in spirals, then this
finding is difficult to reconcile with the observed evolution of the spiral/S0
fraction with redshift. Recent star formation could explain the observed lack
of fading in S0s, but the offset of the S0 TFR persists as a function of both
stellar and dynamical mass. We show that the offset of the S0 TFR could
therefore be explained by a systematic difference between the total mass
distributions of S0s and spirals, in the sense that S0s need to be smaller or
more concentrated than spirals.Comment: Accepted for publication in MNRAS; 17 pages; v2 incorporates minor
proof corrections and updated reference