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Real-Time Global Illumination Using OpenGL And Voxel Cone Tracing [article]

Benjamin Kahl
2021 arXiv   pre-print
Voxel Cone Tracing, as proposed by Cyril Crassin et al. in 2011, makes use of mipmapped 3D textures containing a voxelized representation of an environments direct light component to trace diffuse, specular  ...  and occlusion cones in linear time to extrapolate a surface fragments indirect light emitted towards a given photo-receptor.  ...  components during voxel cone tracing.  ... 
arXiv:2104.00618v1 fatcat:up42e762vbdzbb6cmsejostm2a

Three-dimensional iterative reconstruction algorithms with attenuation and geometric point response correction

G.L. Zeng, G.T. Gullberg, B.M.W. Tsui, J.A. Terry
1991 IEEE Transactions on Nuclear Science  
For parallel, fan, and cone beam geometries, iterative reconstruction algorithms have been developed which eliminate these artifacts by incorporating the three-dimensional spatially varying geometric point  ...  Parallel, fan and cone beam ray-tracing geometries. A simulation was performed with a Gaussian phantom which had a FWHM of 11.303 voxels.  ...  Then the third do-loop traces along the ray, determining the contribution to the projection bin of each voxel intersected by the ray.  ... 
doi:10.1109/23.289376 fatcat:utejzkipnrdyfjam54bn7id7me

Colors everywhere: enhanced chromatic processing across the first visual synapse in the zebrafish central brain [article]

Drago A Guggiana Nilo, Clemens Riegler, Mark Hübener, Florian Engert
2020 bioRxiv   pre-print
Larval zebrafish (Danio rerio) are an ideal organism to study color vision, as their eye possesses four types of cone photoreceptors, covering most of the visible range and into the UV [1,2].  ...  To obtain each trace, the traces from each voxel in an ROI were averaged together.  ...  Inset shows the average delta F/F traces for these functional clusters.  ... 
doi:10.1101/2020.06.19.160804 fatcat:u27pasolqnasheizfezyrncqd4

Scalable Spherical Harmonics Hierarchies

Jonathan B. Metzgar, Sudhanshu K. Semwal
2020 Journal of WSCG  
Voxel cone tracing [CNS + 11] is a recent method which projects lighting into a sparse octree and traces cones from surface geometry using final gathering.  ...  Figure 6 shows the process of voxel cone tracing. Rather than tracing rays, VCT proceeds by building a spatial subdivision data structure in which to propagate a light solution.  ... 
doi:10.24132/csrn.2020.3001.14 fatcat:cbf4ew2h6rh2fntnh5ykn35wse

Simplified Voxel Based Visualization

Péter Mileff, Judit Dudra
2019 Production Systems and Information Engineering  
Voxel-based technology has already been present in the early years of computer visualization. However its usage was almost entirely confined to the field of medical image synthesis.  ...  This publication presents a simplified visualization model and optimization techniques, which are able to visualize smaller (perhaps animated) voxel sets in real-time with certain compromises.  ...  Due to the evolution of the GPU, mainly the approaches using some kind of ray-based technology (ray-tracing, cone tracing etc.) are showing progress.  ... 
doi:10.32968/psaie.2019.001 fatcat:7wimt6rnxrfzlexzc4foicuu6i

Object voxeliztion by filtering

Miloš Šrámek, Arie Kaufman
1998 Proceedings of the 1998 IEEE symposium on Volume visualization - VVS '98  
However, impressive results were obtained by a discrete ray tracing [9] .  ...  Then, the convolution Eq. 3 becomes Sf (p) = Ill J(z -Z(zz, u),y -Y(U,0),2 -2(U,0)) fbz -X,PY-U,pz -z)dzdydz, (17) where 6(.) is Dirac's delta function.  ... 
doi:10.1145/288126.288178 dblp:conf/vvs/SramekK98 fatcat:u34iowuckfhhldhfg34iavif7m

Fast high-resolution micro-CT with exact reconstruction methods

T. Varslot, A. Kingston, A. Sheppard, A. Sakellariou, Stuart R. Stock
2010 Developments in X-Ray Tomography VII  
In this paper, we present some challenges which arise when adopting this approach in a high-resolution cone-beam micro-CT system.  ...  We employ a helical scanning trajectory, accompanied by an exact reconstruction method to avoid the artifacts resulting from the use of large cone-angles with circular trajectories.  ...  Simple ray tracing shows that a source spot of radius r will project the delta function to a blurry spot of diameter r(L − R)/R.  ... 
doi:10.1117/12.860298 fatcat:x2chljmiajgrtmzvpsaersehh4

Real-time dose computation: GPU-accelerated source modeling and superposition/convolution

Robert Jacques, John Wong, Russell Taylor, Todd McNutt
2010 Medical Physics (Lancaster)  
The authors introduce the concepts of arc superposition and delta superposition.  ...  Superposition/convolution was implemented using the inverse cumulative-cumulative kernel and exact radiological path ray-tracing.  ...  Lastly, full dose deposition can be calculated for the subset of voxels that would normally be affected by a delta dose computation.  ... 
doi:10.1118/1.3483785 pmid:21361198 fatcat:l2gg4s56wvb77laav7zjoqlj2q

Optimizing cone beam CT scatter estimation in egs_cbct for a clinical and virtual chest phantom

Rune Slot Thing, Ernesto Mainegra-Hing
2014 Medical Physics (Lancaster)  
Delta transport Photons not aimed at the detector are transported using socalled delta transport or Woodcock tracing.  ...  An exact ray-tracing algorithm is implemented to account for the attenuation through the phantom. 2.B.2.  ... 
doi:10.1118/1.4881142 pmid:24989380 fatcat:ozglbgessbeaxhucqqzjuzaecm

Shape tracing: An extension of sphere tracing for 3D non-convex collision in protein docking

Adam Leach, Lucas S.P. Rudden, Sam Bond-Taylor, John C. Brigham, Matteo T. Degiacomi, Chris G. Willcocks
2020 2020 IEEE 20th International Conference on Bioinformatics and Bioengineering (BIBE)  
This paper presents an algorithm, similar to implicit sphere tracing, that ray marches 3D non-convex shapes for efficient collision detection.  ...  Docking with shape tracing: the source shape (ligand) is initialised on random points on a sphere around the target shape (receptor) with inward facing cones (1).  ...  We investigated the relationship between cone width and solutions quality by varying the cone parameter γ. Best solutions after 5,000 iterations were averaged over 10 runs.  ... 
doi:10.1109/bibe50027.2020.00016 fatcat:kmubqlyq4va3pba2wz5liydd74

A survey of shadow algorithms

A. Woo, P. Poulin, A. Fournier
1990 IEEE Computer Graphics and Applications  
Cone tracing traces a single conic pencil to get a better approximation.  ...  Pencil tracing is basically an intermediary between cone tracing and ray tracing. Ray tracing traces lines so that only point sampled information can be gathered.  ... 
doi:10.1109/38.62693 fatcat:rbxx4ryxwnfqvhx7aqsik3b3wu

Ca2+ signaling in astrocytes is sleep-wake state specific and modulates sleep [article]

Laura Bojarskaite, Daniel Marelius Bjørnstad, Klas Henning Pettersen, Céline Cunen, Gudmund Horn Hermansen, Knut Sindre Åbjørsbråten, Rolf Sprengel, Koen Vervaeke, Wannan Tang, Rune Enger, Erlend Arnulf Nagelhus
2019 bioRxiv   pre-print
the trace.  ...  To define thresholds for event detection, traces of the noise was approximated by subtracting the smoothed trace from the raw ΔF/F0 trace.  ... 
doi:10.1101/750281 fatcat:pgudksjw4nhi7n3cz5qormzgbm

Fast re-rendering of volume and surface graphics by depth, color, and opacity buffering

A Bhalerao, Hanspeter Pfister, Michael Halle, Ron Kikinis
2000 Medical Image Analysis  
Contiguous sets of voxels (segments) are grouped together if the differential opacity between pairs of voxels is less than an opacity-delta value, δ = α i + 1 ,α i .  ...  Next, the sphere is made semi-transparent, and then the cone. In the next row, both the cone and sphere are shown semi-transparent.  ... 
doi:10.1016/s1361-8415(00)00017-7 pmid:11145311 fatcat:spdytvqm3radxeciivzcefkbry

Tomographic approach for the quantitative scene reconstruction from light field images

Nicola Viganò, Henri Der Sarkissian, Charlotte Herzog, Ombeline de la Rochefoucauld, Robert van Liere, Kees Joost Batenburg
2018 Optics Express  
Current computational methods for light field photography model the ray-tracing geometry inside the plenoptic camera.  ...  We propose a representation that leads to the correct reconstruction of object sizes and distances to the camera, by showing that light field images can be interpreted as limited angle cone-beam tomography  ...  We will refer to different ray tracing models as ray parametrizations.  ... 
doi:10.1364/oe.26.022574 pmid:30184917 fatcat:mwvh3ojvpbfttgvdqqe7vm65hm

Data correlation based noise level estimation for cone beam projection data

Ti Bai, Hao Yan, Luo Ouyang, David Staub, Jing Wang, Xun Jia, Steve B. Jiang, Xuanqin Mou
2017 Journal of X-Ray Science and Technology  
Let us consider an object composed of a delta function point, which located at distance r from the origin and at angle ϕ with respect to the x-axis.  ...  CONCLUSIONS-Based on the data correlation of cone beam projection data in Fourier domain, the proposed algorithm could estimate the noise level of cone beam projection data accurately and robustly.  ...  The phantom has a dimension of 512 × 512 × 80 and a voxel size of 0.057 × 0.057 × 0.25cm 3 . Based on this phantom, cone beam projections are generated.  ... 
doi:10.3233/xst-17266 pmid:28697578 pmcid:PMC5714667 fatcat:a7xdo52d7vb5rfc3w6bqcrjlfm
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