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Dirk Bauer, Ronny Peikert, Mie Sato
Scale-space
techniques have become popular in computer vision for their
capability to access the multi-scale information inherently contained
in images. In this project, we show that the field of flow
visualization can benefit from these techniques, too, yielding more
coherent features and sorting out numerical artifacts as well as
irrelevant large-scale features. It is possible to implement the
scale-space computation also for time-dependent CFD data. Feature
tracking allows to process the information provided by the scale-space
not just visually but also algorithmically. To achieve this goal, we
developed a technique for extending a class of feature extraction
schemes by an additional dimension, resulting in an efficient solution
of the vortex tracking problem.In the same project, we explore
techniques for the purpose of visualizing isolated flow structures in
time-dependent data. Our primary industrial application is the
visualization of the vortex rope, a rotating helical structure which
builds up in the draft tube of a water turbine. The vortex rope can be
characterized by high values of normalized helicity, which is a scalar
field derived from the given CFD velocity data. In two related
applications, the goal is to visualize the cavitation regions near the
runner blades of a Kaplan turbine and a water pump, respectively.
Again, the flow structure of interest can be defined by a scalar field,
namely by low pressure values. We proposed a particle seeding scheme
based on quasi-random numbers, which minimizes visual artifacts such as
clusters or patterns. By constraining the visualization to a region of
interest, occlusion problems are reduced and storage efficiency is
gained.
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- D. Bauer, Selective Visualisation of Unsteady 3D Flow using Scale-Space and Feature-Based Techniques, Dissertation No.16640, ETH Zurich, 2006.
[PDF] [BibTeX]
- M. Sato, R. Peikert, Core-Line-Based Vortex Hulls in Turbomachinery Flows, Journal of the Visualization Society of Japan, Vol.23 Suppl. No. 2, pp. 151-154 (Utsunomiya Visualization Symposium, 2003)
[Abstract]
[PDF]
- D. Bauer, R. Peikert, M. Sato, M. Sick, A Case Study in Selective Visualization of Unsteady 3D Flow. In: Proceedings of IEEE Visualization '02, IEEE Computer Society Press, pp. 525-528, (Visualization '02, Boston, MA, USA, October 27-November 1, 2002).
[PDF] [BibTeX]
- D. Bauer, R. Peikert, Vortex Tracking in Scale-Space. In: Joint EUROGRAPHICS - IEEE TCVG Symposium on Visualization (2002), pp. 233-240, VisSym'02, Barcelona, May 27-29, 2002.
[PDF] [BibTeX]
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