7,654 research outputs found
The UTMOST: A hybrid digital signal processor transforms the MOST
The Molonglo Observatory Synthesis Telescope (MOST) is an 18,000 square meter
radio telescope situated some 40 km from the city of Canberra, Australia. Its
operating band (820-850 MHz) is now partly allocated to mobile phone
communications, making radio astronomy challenging. We describe how the
deployment of new digital receivers (RX boxes), Field Programmable Gate Array
(FPGA) based filterbanks and server-class computers equipped with 43 GPUs
(Graphics Processing Units) has transformed MOST into a versatile new
instrument (the UTMOST) for studying the dynamic radio sky on millisecond
timescales, ideal for work on pulsars and Fast Radio Bursts (FRBs). The
filterbanks, servers and their high-speed, low-latency network form part of a
hybrid solution to the observatory's signal processing requirements. The
emphasis on software and commodity off-the-shelf hardware has enabled rapid
deployment through the re-use of proven 'software backends' for its signal
processing. The new receivers have ten times the bandwidth of the original MOST
and double the sampling of the line feed, which doubles the field of view. The
UTMOST can simultaneously excise interference, make maps, coherently dedisperse
pulsars, and perform real-time searches of coherent fan beams for dispersed
single pulses. Although system performance is still sub-optimal, a pulsar
timing and FRB search programme has commenced and the first UTMOST maps have
been made. The telescope operates as a robotic facility, deciding how to
efficiently target pulsars and how long to stay on source, via feedback from
real-time pulsar folding. The regular timing of over 300 pulsars has resulted
in the discovery of 7 pulsar glitches and 3 FRBs. The UTMOST demonstrates that
if sufficient signal processing can be applied to the voltage streams it is
possible to perform innovative radio science in hostile radio frequency
environments.Comment: 12 pages, 6 figure
Short-time Fourier transform laser Doppler holography
We report a demonstration of laser Doppler holography at a sustained
acquisition rate of 250 Hz on a 1 Megapixel complementary
metal-oxide-semiconductor (CMOS) sensor array and image display at 10 Hz frame
rate. The holograms are optically acquired in off-axis configuration, with a
frequency-shifted reference beam. Wide-field imaging of optical fluctuations in
a 250 Hz frequency band is achieved by turning time-domain samplings to the
dual domain via short-time temporal Fourier transformation. The measurement
band can be positioned freely within the low radio-frequency spectrum by tuning
the frequency of the reference beam in real-time. Video-rate image rendering is
achieved by streamline image processing with commodity computer graphics
hardware. This experimental scheme is validated by a non-contact vibrometry
experiment
Shape Completion using 3D-Encoder-Predictor CNNs and Shape Synthesis
We introduce a data-driven approach to complete partial 3D shapes through a
combination of volumetric deep neural networks and 3D shape synthesis. From a
partially-scanned input shape, our method first infers a low-resolution -- but
complete -- output. To this end, we introduce a 3D-Encoder-Predictor Network
(3D-EPN) which is composed of 3D convolutional layers. The network is trained
to predict and fill in missing data, and operates on an implicit surface
representation that encodes both known and unknown space. This allows us to
predict global structure in unknown areas at high accuracy. We then correlate
these intermediary results with 3D geometry from a shape database at test time.
In a final pass, we propose a patch-based 3D shape synthesis method that
imposes the 3D geometry from these retrieved shapes as constraints on the
coarsely-completed mesh. This synthesis process enables us to reconstruct
fine-scale detail and generate high-resolution output while respecting the
global mesh structure obtained by the 3D-EPN. Although our 3D-EPN outperforms
state-of-the-art completion method, the main contribution in our work lies in
the combination of a data-driven shape predictor and analytic 3D shape
synthesis. In our results, we show extensive evaluations on a newly-introduced
shape completion benchmark for both real-world and synthetic data
Future Directions in Astronomy Visualisation
Despite the large budgets spent annually on astronomical research equipment
such as telescopes, instruments and supercomputers, the general trend is to
analyse and view the resulting datasets using small, two-dimensional displays.
We report here on alternative advanced image displays, with an emphasis on
displays that we have constructed, including stereoscopic projection, multiple
projector tiled displays and a digital dome. These displays can provide
astronomers with new ways of exploring the terabyte and petabyte datasets that
are now regularly being produced from all-sky surveys, high-resolution computer
simulations, and Virtual Observatory projects. We also present a summary of the
Advanced Image Displays for Astronomy (AIDA) survey which we conducted from
March-May 2005, in order to raise some issues pertitent to the current and
future level of use of advanced image displays.Comment: 13 pages, 2 figures, accepted for publication in PAS
Musica ex machina:a history of video game music
The history of video game music is a subject area that has received little attention by musicologists, and yet the form presents fascinating case studies both of musical minimalism, and the role of technology in influencing and shaping both musical form and aesthetics. This presentation shows how video game music evolved from simple tones, co-opted from sync circuits in early hardware to a sophisticated form of adaptive expression
ScanNet++: A High-Fidelity Dataset of 3D Indoor Scenes
We present ScanNet++, a large-scale dataset that couples together capture of
high-quality and commodity-level geometry and color of indoor scenes. Each
scene is captured with a high-end laser scanner at sub-millimeter resolution,
along with registered 33-megapixel images from a DSLR camera, and RGB-D streams
from an iPhone. Scene reconstructions are further annotated with an open
vocabulary of semantics, with label-ambiguous scenarios explicitly annotated
for comprehensive semantic understanding. ScanNet++ enables a new real-world
benchmark for novel view synthesis, both from high-quality RGB capture, and
importantly also from commodity-level images, in addition to a new benchmark
for 3D semantic scene understanding that comprehensively encapsulates diverse
and ambiguous semantic labeling scenarios. Currently, ScanNet++ contains 460
scenes, 280,000 captured DSLR images, and over 3.7M iPhone RGBD frames.Comment: ICCV 2023. Video: https://youtu.be/E6P9e2r6M8I , Project page:
https://cy94.github.io/scannetpp
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