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Doppler Speckles – A Multi-Purpose Vectoreld Visualization Technique for Arbitrary Meshes. Werner Benger 1 and Georg Ritter 3 and Simon Su 4 and Dimitris E. Nikitopoulos 2 and Eamonn Walker 2 and Sumanta Acharya 2 and Somnath Roy 2 and Farid Harhad 1 and Wolfgang Kapferer 3
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Doppler Speckles –A Multi-Purpose VectoreldVisualization Technique for Arbitrary Meshes Werner Benger1 and Georg Ritter3 and Simon Su4 and Dimitris E. Nikitopoulos2 and Eamonn Walker2 and Sumanta Acharya2 and Somnath Roy2 and Farid Harhad1 and Wolfgang Kapferer3 1Center for Computation and Technology, Louisiana State University, USA 2Department for Mechanical Engineering, Louisiana State University, USA 3Institute for Astro- and Particle Physics, University of Innsbruck 4Princeton Institute for Computational Science and Engineering
Outline • The Problem • The Approach • Application Examples
The Problem Visualizing Vectors in 3D & 4D
The Approach • Splatting Technique: Drawing of Gaussian spots as billboard per vertex • Used for Volume Rendering of Unstructured Meshes • Gaussian splats in view plane – Efficiently done via OpenGL Point Sprites
Vector Speckle • Elongate along direction of vector in a field Stretch Orient Offset
Vector Speckle - Stretch • Stretch according to Vector Magnitude • Freedom in various scaling factors and mappings (like vector arrows)
Vector Speckle - Orientation • Compute Projection of Vector in View Plane • View-dependent shape – requires GL fragment shader View Plane
Vector Speckle - Offset Free parameter to allow animation of display element T=0.0 T=0.2 T=0.5
Doppler Effect • Physical Effect: movement of wave-emitting objects influences observed frequency • Known as sound of passing street cars: • Movement to observer increases frequency • Movement from observer decreases frequency • Light: Color change of moving objects • Approaching - higher frequency – blueshift • Escaping - lower frequency - redshift
Application Examples • Couette Flow (Analytic Vector field) • Microchannel Droplet (Uniform Grid) • Stirtank Fluid (Curvilinear Multiblock) • Galaxy Evolution (Particle System)
Couette Flow Vector arrows Doppler speckles
Couette Flow Streamlines Doppler speckles
Couette Flow Down view Up view
Microchannel Droplet Front view Back view
Streamlines Enhanced Streamlines Speckles on streamlines
Streamlines Enhanced Streamlines Speckles on streamlines
Stir Tank • 2088 Curvilinear Blocks
Side view Up view
Evolving Galaxies • 16 Million particles, each representing one galaxy • Cosmological evolution over several billion years • 300GB of raw data • Velocity given for each galaxy
Availability • Algorithms implemented and available in • Vish – Visualization Shell • Freely available for academic usage • Code development management: • http://sciviz.cct.lsu.edu/projects/vish • Available via SVN in source code for registered users at http://vish.origo.ethz.ch/