179 research outputs found
Fast self-shadowing using occluder textures
A real-time self-shadowing technique is described. State of the art shadowing techniques that utilize
modern hardware often require multiple rendering passes and introduce rendering artifacts. Combining
separate ideas from earlier techniques which project geometry onto a plane and project imagery onto an
object results in a new real-time technique for self-shadowing. This technique allows an artist to construct
occluder textures and assign them to shadow planes for a self-shadowed model. Utilizing a graphics
processing unit (GPU), a vertex program computes shadowing coordinates in real-time, while a fragment
program applies the shading and shadowing in a single rendering pass. The methodology used to create
shadow planes and write the vertex and fragment programs is given, as well as the relation to the previous
work. This work includes implementing this technique, applying it to a small set of test models, describing
the types of models for which the technique is well suited, as well as those for which it is not well suited,
and comparing the techniqueĂÂąĂĂs performance and image quality to other state of the art shadowing
techniques. This technique performs as well as other real-time techniques and can reduce rendering
artifacts in certain circumstances
Fast self-shadowing using occluder textures
A real-time self-shadowing technique is described. State of the art shadowing techniques that utilize
modern hardware often require multiple rendering passes and introduce rendering artifacts. Combining
separate ideas from earlier techniques which project geometry onto a plane and project imagery onto an
object results in a new real-time technique for self-shadowing. This technique allows an artist to construct
occluder textures and assign them to shadow planes for a self-shadowed model. Utilizing a graphics
processing unit (GPU), a vertex program computes shadowing coordinates in real-time, while a fragment
program applies the shading and shadowing in a single rendering pass. The methodology used to create
shadow planes and write the vertex and fragment programs is given, as well as the relation to the previous
work. This work includes implementing this technique, applying it to a small set of test models, describing
the types of models for which the technique is well suited, as well as those for which it is not well suited,
and comparing the techniqueĂÂąĂĂs performance and image quality to other state of the art shadowing
techniques. This technique performs as well as other real-time techniques and can reduce rendering
artifacts in certain circumstances
Fast self-shadowing using occluder textures
A real-time self-shadowing technique is described. State of the art shadowing techniques that utilize
modern hardware often require multiple rendering passes and introduce rendering artifacts. Combining
separate ideas from earlier techniques which project geometry onto a plane and project imagery onto an
object results in a new real-time technique for self-shadowing. This technique allows an artist to construct
occluder textures and assign them to shadow planes for a self-shadowed model. Utilizing a graphics
processing unit (GPU), a vertex program computes shadowing coordinates in real-time, while a fragment
program applies the shading and shadowing in a single rendering pass. The methodology used to create
shadow planes and write the vertex and fragment programs is given, as well as the relation to the previous
work. This work includes implementing this technique, applying it to a small set of test models, describing
the types of models for which the technique is well suited, as well as those for which it is not well suited,
and comparing the techniqueĂÂąĂĂs performance and image quality to other state of the art shadowing
techniques. This technique performs as well as other real-time techniques and can reduce rendering
artifacts in certain circumstances
The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe
The preponderance of matter over antimatter in the early Universe, the
dynamics of the supernova bursts that produced the heavy elements necessary for
life and whether protons eventually decay --- these mysteries at the forefront
of particle physics and astrophysics are key to understanding the early
evolution of our Universe, its current state and its eventual fate. The
Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed
plan for a world-class experiment dedicated to addressing these questions. LBNE
is conceived around three central components: (1) a new, high-intensity
neutrino source generated from a megawatt-class proton accelerator at Fermi
National Accelerator Laboratory, (2) a near neutrino detector just downstream
of the source, and (3) a massive liquid argon time-projection chamber deployed
as a far detector deep underground at the Sanford Underground Research
Facility. This facility, located at the site of the former Homestake Mine in
Lead, South Dakota, is approximately 1,300 km from the neutrino source at
Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino
charge-parity symmetry violation and mass ordering effects. This ambitious yet
cost-effective design incorporates scalability and flexibility and can
accommodate a variety of upgrades and contributions. With its exceptional
combination of experimental configuration, technical capabilities, and
potential for transformative discoveries, LBNE promises to be a vital facility
for the field of particle physics worldwide, providing physicists from around
the globe with opportunities to collaborate in a twenty to thirty year program
of exciting science. In this document we provide a comprehensive overview of
LBNE's scientific objectives, its place in the landscape of neutrino physics
worldwide, the technologies it will incorporate and the capabilities it will
possess.Comment: Major update of previous version. This is the reference document for
LBNE science program and current status. Chapters 1, 3, and 9 provide a
comprehensive overview of LBNE's scientific objectives, its place in the
landscape of neutrino physics worldwide, the technologies it will incorporate
and the capabilities it will possess. 288 pages, 116 figure
The Science Performance of JWST as Characterized in Commissioning
This paper characterizes the actual science performance of the James Webb
Space Telescope (JWST), as determined from the six month commissioning period.
We summarize the performance of the spacecraft, telescope, science instruments,
and ground system, with an emphasis on differences from pre-launch
expectations. Commissioning has made clear that JWST is fully capable of
achieving the discoveries for which it was built. Moreover, almost across the
board, the science performance of JWST is better than expected; in most cases,
JWST will go deeper faster than expected. The telescope and instrument suite
have demonstrated the sensitivity, stability, image quality, and spectral range
that are necessary to transform our understanding of the cosmos through
observations spanning from near-earth asteroids to the most distant galaxies.Comment: 5th version as accepted to PASP; 31 pages, 18 figures;
https://iopscience.iop.org/article/10.1088/1538-3873/acb29
A communal catalogue reveals Earth's multiscale microbial diversity
Our growing awareness of the microbial world's importance and diversity contrasts starkly with our limited understanding of its fundamental structure. Despite recent advances in DNA sequencing, a lack of standardized protocols and common analytical frameworks impedes comparisons among studies, hindering the development of global inferences about microbial life on Earth. Here we present a meta-analysis of microbial community samples collected by hundreds of researchers for the Earth Microbiome Project. Coordinated protocols and new analytical methods, particularly the use of exact sequences instead of clustered operational taxonomic units, enable bacterial and archaeal ribosomal RNA gene sequences to be followed across multiple studies and allow us to explore patterns of diversity at an unprecedented scale. The result is both a reference database giving global context to DNA sequence data and a framework for incorporating data from future studies, fostering increasingly complete characterization of Earth's microbial diversity.Peer reviewe
A communal catalogue reveals Earthâs multiscale microbial diversity
Our growing awareness of the microbial worldâs importance and diversity contrasts starkly with our limited understanding of its fundamental structure. Despite recent advances in DNA sequencing, a lack of standardized protocols and common analytical frameworks impedes comparisons among studies, hindering the development of global inferences about microbial life on Earth. Here we present a meta-analysis of microbial community samples collected by hundreds of researchers for the Earth Microbiome Project. Coordinated protocols and new analytical methods, particularly the use of exact sequences instead of clustered operational taxonomic units, enable bacterial and archaeal ribosomal RNA gene sequences to be followed across multiple studies and allow us to explore patterns of diversity at an unprecedented scale. The result is both a reference database giving global context to DNA sequence data and a framework for incorporating data from future studies, fostering increasingly complete characterization of Earthâs microbial diversity
The James Webb Space Telescope Mission
Twenty-six years ago a small committee report, building on earlier studies,
expounded a compelling and poetic vision for the future of astronomy, calling
for an infrared-optimized space telescope with an aperture of at least .
With the support of their governments in the US, Europe, and Canada, 20,000
people realized that vision as the James Webb Space Telescope. A
generation of astronomers will celebrate their accomplishments for the life of
the mission, potentially as long as 20 years, and beyond. This report and the
scientific discoveries that follow are extended thank-you notes to the 20,000
team members. The telescope is working perfectly, with much better image
quality than expected. In this and accompanying papers, we give a brief
history, describe the observatory, outline its objectives and current observing
program, and discuss the inventions and people who made it possible. We cite
detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space
Telescope Overview, 29 pages, 4 figure
In-situ estimation of ice crystal properties at the South Pole using LED calibration data from the IceCube Neutrino Observatory
The IceCube Neutrino Observatory instruments about 1 km3 of deep, glacial ice at the geographic South Pole using 5160 photomultipliers to detect Cherenkov light emitted by charged relativistic particles. A unexpected light propagation effect observed by the experiment is an anisotropic attenuation, which is aligned with the local flow direction of the ice. Birefringent light propagation has been examined as a possible explanation for this effect. The predictions of a first-principles birefringence model developed for this purpose, in particular curved light trajectories resulting from asymmetric diffusion, provide a qualitatively good match to the main features of the data. This in turn allows us to deduce ice crystal properties. Since the wavelength of the detected light is short compared to the crystal size, these crystal properties do not only include the crystal orientation fabric, but also the average crystal size and shape, as a function of depth. By adding small empirical corrections to this first-principles model, a quantitatively accurate description of the optical properties of the IceCube glacial ice is obtained. In this paper, we present the experimental signature of ice optical anisotropy observed in IceCube LED calibration data, the theory and parametrization of the birefringence effect, the fitting procedures of these parameterizations to experimental data as well as the inferred crystal properties.</p
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