1 http://cs.swan.ac.uk/~csbob/

Robert S. Larameer.s.laramee@swansea.ac.uk

Glyph and Streamline Placement Algorithms for CFD Simulation Data

Zhenmin Peng1, Robert S. Laramee1, Guoning Chen2, and Eugene Zhang2

1The Visual and Interactive Computing Group

Computer Science Dept.Swansea University

Swansea, Wales, UK{cszp, r.s.laramee } “at” swansea.ac.uk

2School of Electrical Engineering and Computer Science, Oregon State University

Corvallis, OR 97331. {chengu,zhange} “at” eecs.oregonstate.edu.

2 http://cs.swan.ac.uk/~csbob/

Robert S. Larameer.s.laramee@swansea.ac.uk

Overview Challenges Posed by Simulation

Data Flow Visualization: An Introduction Visualization Using Glyphs

Problems Solution: User Options and

Demonstration Flow Visualization with

Streamlines Seeding Problem Streamlines

Problems and Challenges User Options and

Demonstration Conclusions and Summary

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Robert S. Larameer.s.laramee@swansea.ac.uk

Challenges Posed by CFD Simulation Data

Engineers often start with boundary surface when investigating simulation results.

Meshes Used in CFD Simulation:

complex unstructured adaptive resolution

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Robert S. Larameer.s.laramee@swansea.ac.uk

What is Flow Visualization?

A classic topic within scientific visualization Depiction of vector quantities (as opposed to scalar

quantities) Applications include automotive simulation, aerodynamics,

turbo machinery, meteorology, oceanography, medical visualization

Challenges: To effectively visualize both magnitude + direction, often

simultaneously Large, time-dependent data sets Interaction, seeding, and placement, Computation time and irregular grids Perception

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Robert S. Larameer.s.laramee@swansea.ac.uk

Flow Visualization Using Glyphs: Problem

Naïve approach: place arrow glyph at each sample point on mesh, a.k.a Hedgehog visualization.Problems:

glyphs too small to see (or)

glyphs too large and overlap

artifacts from mesh misleading for

interpretation

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Robert S. Larameer.s.laramee@swansea.ac.uk

Flow Visualization Using Glyphs: Solution

New approach: resample vector field onto regular mesh: glyph placement

controlled by user user defined grid

resolution multiple grids possible interaction: rotation,

scaling, and sliding possible

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Robert S. Larameer.s.laramee@swansea.ac.uk

Flow Visualization Using Glyphs: Demo

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Robert S. Larameer.s.laramee@swansea.ac.uk

Flow Visualization Using Streamlines: Seeding Problem

Streamline: a curve everywhere tangent to the vector field, very commonChallenges: Where should the streamlines be placed? How do we ensure properties of flow are adequately

covered? How do we prevent

streamlines from clumping together? Regularly spaced seeds

do not result in regularly spaced streamlines.

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Robert S. Larameer.s.laramee@swansea.ac.uk

Flow Visualization Using Streamlines: Seeding Solution

Evenly-spaced streamlines on surfacesAdvantages: Streamlines can be

distributed evenly in image space User controls spatial

frequency (separating distance) between curves User interaction: zooming,

panning supported, fast rendering times

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Robert S. Larameer.s.laramee@swansea.ac.uk

Streamline Seeding on Surfaces: Demo

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Robert S. Larameer.s.laramee@swansea.ac.uk

Summary and Conclusions Glyph and streamline placement is very

difficult for CFD simulation data

We present both glyph and streamline placement strategies for this application

Strategies support full user-interaction and fast rendering speeds

More implementation details can be found in paper.

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Robert S. Larameer.s.laramee@swansea.ac.uk

Acknowledgements Thank you for your attention! Any

questions?

We would like to thank the following: Ben Spencer of Swansea University and the EPSRC for funding

this research

PDF versions of papers and MPEG movies available at:

http://cs.swan.ac.uk/~csbob