79,592 research outputs found
Meetings and Meeting Modeling in Smart Environments
In this paper we survey our research on smart meeting rooms and its relevance for augmented reality meeting support and virtual reality generation of meetings in real time or off-line. The research reported here forms part of the European 5th and 6th framework programme projects multi-modal meeting manager (M4) and augmented multi-party interaction (AMI). Both projects aim at building a smart meeting environment that is able to collect multimodal captures of the activities and discussions in a meeting room, with the aim to use this information as input to tools that allow real-time support, browsing, retrieval and summarization of meetings. Our aim is to research (semantic) representations of what takes place during meetings in order to allow generation, e.g. in virtual reality, of meeting activities (discussions, presentations, voting, etc.). Being able to do so also allows us to look at tools that provide support during a meeting and at tools that allow those not able to be physically present during a meeting to take part in a virtual way. This may lead to situations where the differences between real meeting participants, human-controlled virtual participants and (semi-) autonomous virtual participants disappear
A cryogenic liquid-mirror telescope on the moon to study the early universe
We have studied the feasibility and scientific potential of zenith observing
liquid mirror telescopes having 20 to 100 m diameters located on the moon. They
would carry out deep infrared surveys to study the distant universe and follow
up discoveries made with the 6 m James Webb Space Telescope (JWST), with more
detailed images and spectroscopic studies. They could detect objects 100 times
fainter than JWST, observing the first, high-red shift stars in the early
universe and their assembly into galaxies. We explored the scientific
opportunities, key technologies and optimum location of such telescopes. We
have demonstrated critical technologies. For example, the primary mirror would
necessitate a high-reflectivity liquid that does not evaporate in the lunar
vacuum and remains liquid at less than 100K: We have made a crucial
demonstration by successfully coating an ionic liquid that has negligible vapor
pressure. We also successfully experimented with a liquid mirror spinning on a
superconducting bearing, as will be needed for the cryogenic, vacuum
environment of the telescope. We have investigated issues related to lunar
locations, concluding that locations within a few km of a pole are ideal for
deep sky cover and long integration times. We have located ridges and crater
rims within 0.5 degrees of the North Pole that are illuminated for at least
some sun angles during lunar winter, providing power and temperature control.
We also have identified potential problems, like lunar dust. Issues raised by
our preliminary study demand additional in-depth analyses. These issues must be
fully examined as part of a scientific debate we hope to start with the present
article.Comment: 35 pages, 11 figures. To appear in Astrophysical Journal June 20 200
The Gaia Ultra-Cool Dwarf Sample -- II : Structure at the end of the main sequence
Ā© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.We identify and investigate known late M, L, and T dwarfs in the Gaia second data release. This sample is being used as a training set in the Gaia data processing chain of the ultracool dwarfs work package. We find 695 objects in the optical spectral range M8āT6 with accurate Gaia coordinates, proper motions, and parallaxes which we combine with published spectral types and photometry from large area optical and infrared sky surveys. We find that 100 objects are in 47 multiple systems, of which 27 systems are published and 20 are new. These will be useful benchmark systems and we discuss the requirements to produce a complete catalogue of multiple systems with an ultracool dwarf component. We examine the magnitudes in the Gaia passbands and find that the G BP magnitudes are unreliable and should not be used for these objects. We examine progressively redder colourāmagnitude diagrams and see a notable increase in the main-sequence scatter and a bivariate main sequence for old and young objects. We provide an absolute magnitude ā spectral subtype calibration for G and G RP passbands along with linear fits over the range M8āL8 for other passbands.Peer reviewedFinal Published versio
Computationally Efficient Target Classification in Multispectral Image Data with Deep Neural Networks
Detecting and classifying targets in video streams from surveillance cameras
is a cumbersome, error-prone and expensive task. Often, the incurred costs are
prohibitive for real-time monitoring. This leads to data being stored locally
or transmitted to a central storage site for post-incident examination. The
required communication links and archiving of the video data are still
expensive and this setup excludes preemptive actions to respond to imminent
threats. An effective way to overcome these limitations is to build a smart
camera that transmits alerts when relevant video sequences are detected. Deep
neural networks (DNNs) have come to outperform humans in visual classifications
tasks. The concept of DNNs and Convolutional Networks (ConvNets) can easily be
extended to make use of higher-dimensional input data such as multispectral
data. We explore this opportunity in terms of achievable accuracy and required
computational effort. To analyze the precision of DNNs for scene labeling in an
urban surveillance scenario we have created a dataset with 8 classes obtained
in a field experiment. We combine an RGB camera with a 25-channel VIS-NIR
snapshot sensor to assess the potential of multispectral image data for target
classification. We evaluate several new DNNs, showing that the spectral
information fused together with the RGB frames can be used to improve the
accuracy of the system or to achieve similar accuracy with a 3x smaller
computation effort. We achieve a very high per-pixel accuracy of 99.1%. Even
for scarcely occurring, but particularly interesting classes, such as cars, 75%
of the pixels are labeled correctly with errors occurring only around the
border of the objects. This high accuracy was obtained with a training set of
only 30 labeled images, paving the way for fast adaptation to various
application scenarios.Comment: Presented at SPIE Security + Defence 2016 Proc. SPIE 9997, Target and
Background Signatures I
Evaluation of optimisation techniques for multiscopic rendering
A thesis submitted to the University of Bedfordshire in fulfilment of the requirements for the degree of Master of Science by ResearchThis project evaluates different performance optimisation techniques applied to stereoscopic and multiscopic rendering for interactive applications. The artefact
features a robust plug-in package for the Unity game engine. The thesis provides background information for the performance optimisations, outlines all the findings, evaluates the optimisations and provides suggestions for future work.
Scrum development methodology is used to develop the artefact and quantitative research methodology is used to evaluate the findings by measuring performance.
This project concludes that the use of each performance optimisation has specific use case scenarios in which performance benefits. Foveated rendering provides
greatest performance increase for both stereoscopic and multiscopic rendering but is also more computationally intensive as it requires an eye tracking solution.
Dynamic resolution is very beneficial when overall frame rate smoothness is needed and frame drops are present. Depth optimisation is beneficial for vast open environments but can lead to decreased performance if used inappropriately
New nearby white dwarfs from Gaia DR1 TGAS and UCAC5/URAT
Using an accurate Gaia TGAS 25pc sample, nearly complete for GK stars, and
selecting common proper motion (CPM) candidates from UCAC5, we search for new
white dwarf (WD) companions around nearby stars with relatively small proper
motions. For investigating known CPM systems in TGAS and for selecting CPM
candidates in TGAS+UCAC5, we took into account the expected effect of orbital
motion on the proper motion as well as the proper motion catalogue errors.
Colour-magnitude diagrams (CMDs) and were used to verify
CPM candidates from UCAC5. Assuming their common distance with a given TGAS
star, we searched for candidates that occupied similar regions in the CMDs as
the few known nearby WDs (4 in TGAS) and WD companions (3 in TGAS+UCAC5). CPM
candidates with colours and absolute magnitudes corresponding neither to the
main sequence nor to the WD sequence were considered as doubtful or subdwarf
candidates. With a minimum proper motion of 60mas/yr, we selected three WD
companion candidates, two of which are also confirmed by their significant
parallaxes measured in URAT data, whereas the third may also be a chance
alignment of a distant halo star with a nearby TGAS star (angular separation of
about 465arcsec). One additional nearby WD candidate was found from its URAT
parallax and photometry. With HD 166435 B orbiting a well-known G1 star
at ~24.6pc with a projected physical separation of ~700AU, we discovered one of
the hottest WDs, classified by us as DA2.00.2, in the solar neighbourhood.
We also found TYC 3980-1081-1 B, a strong cool WD companion candidate around a
recently identified new solar neighbour with a TGAS parallax corresponding to a
distance of ~8.3pc and our photometric classification as ~M2 dwarf. This raises
the question whether previous assumptions on the completeness of the WD sample
to a distance of 13pc were correct.Comment: 9 pages, 6 figures, accepted for publication in Astronomy and
Astrophysic
The First Three Rungs of the Cosmological Distance Ladder
It is straightforward to determine the size of the Earth and the distance to
the Moon without making use of a telescope. The methods have been known since
the 3rd century BC. However, few amateur or professional astronomers have
worked this out from data they themselves have taken. Here we use a gnomon to
determine the latitude and longitude of South Bend, Indiana, and College
Station, Texas, and determine a value of the radius of the Earth of 6290 km,
only 1.4 percent smaller than the true value. We use the method of Aristarchus
and the size of the Earth's shadow during the lunar eclipse of 2011 June 15 to
derive an estimate of the distance to the Moon (62.3 R_Earth), some 3.3 percent
greater than the true mean value. We use measurements of the angular motion of
the Moon against the background stars over the course of two nights, using a
simple cross staff device, to estimate the Moon's distance at perigee and
apogee. Finally, we use simultaneous CCD observations of asteroid 1996 HW1
obtained with small telescopes in Socorro, New Mexico, and Ojai, California, to
derive a value of the Astronomical Unit of (1.59 +/- 0.19) X 10^8 km, about 6
percent too large. The data and methods presented here can easily become part
of a beginning astronomy lab class.Comment: 34 pages, 11 figures, accepted for publication in American Journal of
Physic
Learning Visual Clothing Style with Heterogeneous Dyadic Co-occurrences
With the rapid proliferation of smart mobile devices, users now take millions
of photos every day. These include large numbers of clothing and accessory
images. We would like to answer questions like `What outfit goes well with this
pair of shoes?' To answer these types of questions, one has to go beyond
learning visual similarity and learn a visual notion of compatibility across
categories. In this paper, we propose a novel learning framework to help answer
these types of questions. The main idea of this framework is to learn a feature
transformation from images of items into a latent space that expresses
compatibility. For the feature transformation, we use a Siamese Convolutional
Neural Network (CNN) architecture, where training examples are pairs of items
that are either compatible or incompatible. We model compatibility based on
co-occurrence in large-scale user behavior data; in particular co-purchase data
from Amazon.com. To learn cross-category fit, we introduce a strategic method
to sample training data, where pairs of items are heterogeneous dyads, i.e.,
the two elements of a pair belong to different high-level categories. While
this approach is applicable to a wide variety of settings, we focus on the
representative problem of learning compatible clothing style. Our results
indicate that the proposed framework is capable of learning semantic
information about visual style and is able to generate outfits of clothes, with
items from different categories, that go well together.Comment: ICCV 201
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