DOPPLER SPECKLES –A MULTI-PURPOSE

VECTORELDVISUALIZATION TECHNIQUE

FOR ARBITRARY MESHESWerner Benger1 and Georg Ritter3 and Simon Su4 and

Dimitris E. Nikitopoulos2 and Eamonn Walker2 andSumanta Acharya2 and Somnath Roy2 and

Farid Harhad1 and Wolfgang Kapferer3

1Center for Computation and Technology, Louisiana State University, USA2Department for Mechanical Engineering, Louisiana State University, USA

3Institute for Astro- and Particle Physics, University of Innsbruck4Princeton Institute for Computational Science and Engineering

Outline

The Problem

The Approach

Application Examples

The ProblemVisualizing 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

field1. Stretch

2. Orient

3. Offset

Vector Speckle - Stretch Stretch according to Vector Magnitude

Freedom in various scaling factors and mappings (like vector arrows)

Compute Projection of Vector in View Plane

View-dependent shape – requires GL fragment shader

Vector Speckle - Orientation

View Plane

Vector Speckle - OffsetFree 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 Examples1. Couette Flow (Analytic Vector field)

2. Microchannel Droplet (Uniform Grid)

3. Stirtank Fluid (Curvilinear Multiblock)

4. Galaxy Evolution (Particle System)

Couette FlowVECTOR ARROWS DOPPLER SPECKLES

Couette FlowSTREAMLINES DOPPLER SPECKLES

Couette FlowDOWN VIEW UP VIEW

Microchannel DropletFRONT VIEW BACK VIEW

Streamlines EnhancedSTREAMLINES SPECKLES ON

STREAMLINES

Streamlines EnhancedSTREAMLINES 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

Evolving Galaxies

Evolving Galaxies

Evolving Galaxies

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/