Inviwo — A Visualization System with Usage Abstraction Levels

Jonsson, Dan; Steneteg, Peter; Sundén, E. Andersson; Englund, Rickard; Kottravel, Sathish; Falk, Martin; Ynnerman, Anders; Hotz, Ingrid; Ropinski, Timo

doi:10.1109/tvcg.2019.2920639

Cited by 49 publications

(43 citation statements)

References 44 publications

(65 reference statements)

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“…The inset on the upper right slices the phase space density distribution at x = 3.5 (black square). The rendering was created with Inviwo [18]. over a distance that is much less than λ s .…”

Section: Simulationmentioning

confidence: 99%

Structure of a collisionless pair jet in a magnetized electron–proton plasma: flow-aligned magnetic field

Dieckmann

Folini

Hotz

et al. 2019

A&A

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Aims. We study the effect a guiding magnetic field has on the formation and structure of a pair jet that propagates through a collisionless electron–proton plasma at rest. Methods. We model with a particle-in-cell (PIC) simulation a pair cloud with a temperature of 400 keV and a mean speed of 0.9c (c - light speed). Pair particles are continuously injected at the boundary. The cloud propagates through a spatially uniform, magnetized, and cool ambient electron–proton plasma at rest. The mean velocity vector of the pair cloud is aligned with the uniform background magnetic field. The pair cloud has a lateral extent of a few ion skin depths. Results. A jet forms in time. Its outer cocoon consists of jet-accelerated ambient plasma and is separated from the inner cocoon by an electromagnetic piston with a thickness that is comparable to the local thermal gyroradius of jet particles. The inner cocoon consists of pair plasma, which lost its directed flow energy while it swept out the background magnetic field and compressed it into the electromagnetic piston. A beam of electrons and positrons moves along the jet spine at its initial speed. Its electrons are slowed down and some positrons are accelerated as they cross the head of the jet. The latter escape upstream along the magnetic field, which yields an excess of megaelectronvolt positrons ahead of the jet. A filamentation instability between positrons and protons accelerates some of the protons, which were located behind the electromagnetic piston at the time it formed, to megaelectronvolt energies. Conclusions. A microscopic pair jet in collisionless plasma has a structure that is similar to that predicted by a hydrodynamic model of relativistic astrophysical pair jets. It is a source of megaelectronvolt positrons. An electromagnetic piston acts as the contact discontinuity between the inner and outer cocoons. It would form on subsecond timescales in a plasma with a density that is comparable to that of the interstellar medium in the rest frame of the latter. A supercritical fast magnetosonic shock will form between the pristine ambient plasma and the jet-accelerated plasma on a timescale that exceeds our simulation time by an order of magnitude.

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Section: Simulationmentioning

confidence: 99%

Structure of a collisionless pair jet in a magnetized electron–proton plasma: flow-aligned magnetic field

Dieckmann

Folini

Hotz

et al. 2019

A&A

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“…[LSBP18] for an overview of more techniques in this domain. There are also general systems for prototyping visualizations such as Comvis [MFGH08], Paraview [Aya15] and Inviwo [JSS*19]. These tools can only provide the foundation for a tailored application and, in fact, the presented application is built using the Inviwo [JSS*19] visualization system.…”

Section: Related Workmentioning

confidence: 99%

“…The right‐hand side contains a range of settings as well as a list of the atlas label regions available. The visualization techniques described above are publicly available in the Inviwo [JSS*19] visualization framework.…”

Section: Prototype Visual Analysis Environmentmentioning

confidence: 99%

VisualNeuro: A Hypothesis Formation and Reasoning Application for Multi‐Variate Brain Cohort Study Data

Jonsson

Bergström

Forsell

et al. 2020

Computer Graphics Forum

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We present an application, and its development process, for interactive visual analysis of brain imaging data and clinical measurements. The application targets neuroscientists interested in understanding the correlations between active brain regions and physiological or psychological factors. The application has been developed in a participatory design process and has subsequently been released as the free software ‘VisualNeuro’. From initial observations of the neuroscientists' workflow, we concluded that while existing tools provide powerful analysis options, they lack effective interactive exploration requiring the use of many tools side by side. Consequently, our application has been designed to simplify the workflow combining statistical analysis with interactive visual exploration. The resulting environment comprises parallel coordinates for effective overview and selection, Welch's t‐test to filter out brain regions with statistically significant differences and multiple visualizations for comparison between brain regions and clinical parameters. These exploration concepts enable neuroscientists to interactively explore the complex bidirectional interplay between clinical and brain measurements and easily compare different patient groups. A qualitative user study has been performed with three neuroscientists from different domains. The study shows that the developed environment supports simultaneous analysis of more parameters, provides rapid pathways to insights and is an effective tool for hypothesis formation.

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“…While the analytic solution is good for studying numerical effects it can only be done for trivial functions and does not provide insight into how the sampling strategies are interpreted visually. We therefore implemented the different sampling patterns within the Inviwo visualization framework [15]. Fig.…”

Section: B Visual Analysismentioning

confidence: 99%

Volume Raycasting Sampling Revisited

Steneteg¹,

Jönsson²,

Falk³

et al. 2020

Preprint

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We investigate the effects of practical sample placement strategies when solving the volume rendering integral for interactive volume raycasting with fixed step lengths for each ray. Different sample placements have been used in previous work but they have not been compared with respect to their correctness or visual quality. In this work, the different sampling strategies are presented visually and practical implementation details are provided using algorithmic descriptions of each strategy. A thorough analysis based on comparisons with analytic solutions and real-world data shows that visual artifacts, especially at volume borders, can appear if samples are not placed correctly. Our analysis and comparison results in a sample placement strategy that easily can be integrated into existing implementations, has no impact on performance, and decreases visual artifacts of the rendered image compared to other fixed step size sample strategies.

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Inviwo — A Visualization System with Usage Abstraction Levels

Cited by 49 publications

References 44 publications

Structure of a collisionless pair jet in a magnetized electron–proton plasma: flow-aligned magnetic field

Structure of a collisionless pair jet in a magnetized electron–proton plasma: flow-aligned magnetic field

VisualNeuro: A Hypothesis Formation and Reasoning Application for Multi‐Variate Brain Cohort Study Data

Volume Raycasting Sampling Revisited

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