407 research outputs found
sj-docx-1-spo-10.1177_17479541231152548 - Supplemental material for Utility of video analysis and expert modelling for technique development in novice sport climbers: A randomized controlled study
No full textSupplemental material, sj-docx-1-spo-10.1177_17479541231152548 for Utility of video analysis and expert modelling for technique development in novice sport climbers: A randomized controlled study by Rok Blagus, Bojan Leskošek, Luka Okršlar, Nace Vreček and Tadej Debevec in International Journal of Sports Science & Coaching</p
Accelerating Path Tracing by re-using Paths
No full textThis paper describes a new acceleration technique for rendering algorithms like path tracing, that use so called gathering random walks. Usually in path tracing, each traced path is used in order to compute a contribution to only a single point on the virtual screen. We propose to combine paths traced through nearby screen points in such a way that each path contributes to multiple screen points in a provably good way. Our approach is unbiased and is not restricted to diffuse light scattering. It complements previous image noise reduction techniques for Monte Carlo ray tracing. We observe speed-ups in the computation of indirect illumination of one order of magnitude
Fast Arbitrary BRDF Shading for Low-Frequency Lighting Using Spherical Harmonics
No full textReal-time shading using general (e.g., anisotropic) BRDFs has so far been limited to a few point or directional light sources. We extend such shading to smooth, area lighting using a low-order spherical harmonic basis for the lighting environment. We represent the 4D product function of BRDF times the cosine factor (dot product of the incident lighting and surface normal vectors) as a 2D table of spherical harmonic coefficients. Each table entry represents, for a single view direction, the integral of this product function times lighting on the hemisphere expressed in spherical harmonics. This reduces the shading integral to a simple dot product of 25 component vectors, easily evaluatable on PC graphics hardware. Non-trivial BRDF models require rotating the lighting coefficients to a local frame at each point on an object, currently forming the computational bottleneck. Real-time results can be achieved by fixing the view to allow dynamic lighting or vice versa. We also generalize a previous method for precomputed radiance transfer to handle general BRDF shading. This provides shadows and interreflections that respond in real-time to lighting changes on a preprocessed object of arbitrary material (BRDF) type
Local Illumination Environments for Direct Lighting Acceleration
No full textComputing high-quality direct illumination in scenes with many lights is an open area of research. This paper presents a world-space caching mechanism called local illumination environments that enables interactive direct illumination in complex scenes on a cluster of off-the-shelf PCs. A local illumination environment (LIE) caches geometric and radiometric information related to direct illumination. A LIE is associated with every octree cell constructed over the scene. Each LIE stores a set of visible lights, with associated occluders (if they exist). LIEs are effective at accelerating direct illumination because they both eliminate shadow rays for fully visible and fully occluded regions of the scene, and decrease the cost of shadow rays in other regions. Shadow ray computation for the partially occluded regions is accelerated using the cached potential occluders. One important implication of storing occluders is that rendering is accelerated while producing accurate hard and soft shadows. This paper also describes a simple perceptual metric based on Weber s law that further improves the effectiveness of LIEs in the fully visible and partially occluded regions. LIE construction is view-driven, continuously refined, and asynchronous with the shading process. In complex scenes of hundreds of thousands of polygons with up to a hundred lights, the LIEs improve rendering performance by 10x to 30x over a traditional ray tracer.Eurographics Workshop on Renderin
Long-Term Effects of Prematurity on Resting Ventilatory Response to Hypercapnia.
No full textManferdelli, Giorgio, Benjamin J. Narang, Mathias Poussel, Damjan Osredkar, Grégoire P. Millet, and Tadej Debevec. Long-term effects of prematurity on resting ventilatory response to hypercapnia. High Alt Med Biol. 22:420-425, 2021. Background: This study investigated the resting ventilatory response to hypercapnia in prematurely born adults. Materials and Methods: Seventeen preterm and fourteen full-term adults were exposed to normoxic hypercapnia (two 5-minute periods at 3% and 6% carbon dioxide [CO 2 ] interspersed by 5-minute in normoxia). Pulmonary ventilation ([Formula: see text]) and end-tidal partial pressure of CO 2 (Petco 2 ) were measured continuously. Results: No difference in lung function was observed between preterm and full-term adults. Petco 2 was lower in preterm than in full-term adults (p 2 , both [Formula: see text] and Petco 2 increased in a similar way in preterm and full-term adults. However, at the end of the 6% CO 2 period, there was a significantly higher [Formula: see text] in preterm compared with full-term adults (30.2 ± 7.5 vs. 23.7 ± 4.5 L/min, p 2 (46.9 ± 2.1 vs. 50.6 ± 2.1 L/min, p = 0.99). Breath frequency was higher in preterm than in full-term adults (17.9 ± 4.0 vs. 12.8 ± 3.5 b/min, p 2 exposure. Conclusions: Although data suggest that prematurity results in resting hypocapnia, the exact underlying mechanisms remain to be elucidated. Moreover, preterm adults seem to have increased chemosensitivity to hypercapnia
Exact from-region visibility culling
No full textTo pre-process a scene for the purpose of visibility culling during walkthroughs it is necessary to solve visibility from all the elements of a finite partition of viewpoint space. Many conservative and approximate solutions have been developed that solve for visibility rapidly. The idealised exact solution for general 3D scenes has often been regarded as computationally intractable. Our exact algorithm for finding the visible polygons in a scene from a region is a computationally tractable pre-process that can handle scenes of the order of millions of polygons. The essence of our idea is to represent 3-D polygons and the stabbing lines connecting them in a 5-D Euclidean space derived from Plücker space and then to perform geometric subtractions of occluded lines from the set of potential stabbing lines.We have built a query architecture around this query algorithm that allows for its practical application to large scenes.
We have tested the algorithm on two different types of scene: despite a large constant computational overhead, it is highly scalable, with a time dependency close to linear in the output produced
A measurement of the isovector giant quadrupole resonance in lead-208 using elastic polarized photon scattering
No full textRestriction data tranferred 2014-07-01T11:12:23-05:00
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Reason: ETDs are only available to UIUC Users without author permissionETDs are only available to UIUC Users without author permissionU of I OnlyThis experiment used highly polarized tagged photons to measure polarization asymmetries for elastic scattering in \sp{208}Pb in the energy region of the isovector giant quadrupole resonance (IVGQR). These measurements were performed at excitation energies between 16 and 30 MeV.Photons with enhanced linear polarization were obtained from an off-axis tagged photon beam by making a kinematic selection on the post-bremsstrahlung electrons. Scattered photons were detected in two large NaI(Tl) crystals.The polarization asymmetries clearly show the signature for interference between the isovector giant quadrupole resonance and the underlying electric dipole strength. The gross features of the IVGQR strength distribution were obtained in a relatively model independent manner. An isovector giant quadrupole resonance was observed at an excitation energy of 20.1 0.5 MeV, with a width of 6.3 0.5 MeV, and an energy weighted strength of 1.4 0.3 isovector sum rule units.Made available in DSpace on 2011-05-07T11:51:39Z (GMT). No. of bitstreams: 2
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GigaWalk: Interactive Walkthrough of Complex Environments
No full textWe present a new parallel algorithm and a system, GigaWalk, for interactive walkthrough of complex, gigabytesized environments. Our approach combines occlusion culling and levels-of-detail and uses two graphics pipelines with one or more processors. GigaWalk uses a unified scene graph representation for multiple acceleration techniques, and performs spatial clustering of geometry, conservative occlusion culling, and load-balancing between graphics pipelines and processors. GigaWalk has been used to render CAD environments composed of tens of millions of polygons at interactive rates on systems consisting of two graphics pipelines. Overall, our system s combination of levels-of-detail and occlusion culling techniques results in significant improvements in frame-rate over view-frustum culling or either single technique alone.Eurographics Workshop on Renderin
Towards Real-Time Texture Synthesis with the Jump Map
No full textWhile texture synthesis has been well-studied in recent years, real-time techniques remain elusive. To help facilitate real-time texture synthesis, we divide the task of texture synthesis into two phases: a relatively slow analysis phase, and a real-time synthesis phase. Any particular texture need only be analyzed once, and then an unlimited amount of texture may be synthesized in real-time. Our analysis phase generates a jump map, which stores for each input pixel a set of matching input pixels (jumps). Texture synthesis proceeds in real-time as a random walk through the jump map. Each new pixel is synthesized by extending the patch of input texture from which one of its neighbours was copied. Occasionally, a jump is taken through the jump map to begin a new patch. Despite the method s extreme simplicity, its speed and output quality compares favourably with recent patch-based algorithms.Eurographics Workshop on Renderin
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