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Computer Graphics

Major Thesis of Lukas Zühl

Visualization of Laser-Plasma-Simulations

Lehrstuhl für Computergraphik und Visualisierung

Student: Lukas Zühl
Betreuer: Dr. Ulrich Schramm (HZDR)
Dr. Michael Bussmann (HZDR)
Verantwortlicher Hochschullehrer:  Prof. Dr. Stefan Gumhold

Motivation

The laser particle acceleration division at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) studies the interaction of ultra short, high intensity laser pulses with matter. Numerical simulations of this process are an important method available to analyse the physical processes at a high spacial and temporal resolution. These simulations produce several large datasets that are stored for subsequent analysis and visualization. However, the existing visualization libraries and tools usually focus on visualizing a single dataset at a time, for example a scalar field or a particle cloud at a specific timestep. The aim of this thesis is to enable explorative data analysis by providing an integrated view over all simulation data as well as a flexible mapping of individual data fields to the axes and attributes of a visualization. This enables the scientist to put arbitrary physical variables in relation to each other in order to discover new correlations and create new models.

Description

First the structure of the simulation data is described independent of a possible visualization and of the physical data format. This includes explicitely stored data, such as particle attributes or electrical field values, as well as implicitely available data, such as time and the position of grid points. Different diagrams can be created by assigning individual data fields to the axes and attributes of a visualization. The following visualizations were implemented: Scatter plots can display any three dimensional attribute space by mapping arbitrary data fields to the three axes. Line plots can be used to, for example, visualize the pathlines of particles, trajectories of any kind and function plots. Scalar field visualization using iso-surfaces and vector field visualizations using hedgehogs or streamlines are supported as well.

Furthermore, a declarative language, VQL, has been developed that allows a simple and compact description of these visualizations. A VQL program can either be written directly by the user or created through a graphical user interface (which is beeing developed separately at the HZDR). A corresponding VTK visualization network is created automatically by the program - the user does not need specific knowledge in the field of scientific visualization to create complex visualizations. These simple and flexible configuration methods allow an explorative data visualization that is either not possible or very complex to implement using current programs for scientific visualization.

Results

Visualization of a particle cloud using a scatterplot Scatterplot using the axis-assignments PosX-Energy-PosZ
Pathlines of all particles over six time steps Pathlines of the particles in a plane over 100 time steps
Scalar field visualzation using iso-surfaces Vector field visualization using streamlines
Pathlines of the particles in a plane over 270 time steps

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Last modified: 23rd Apr 2011, 1.32 PM
Author: Corina Weissbach