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Abstract

Occlusion is a crucial spatial cue for the human visual system. Painters as well as researchers in the field of computer graphics have been dealing with this aspect for a long time. In the field of visualization occlusion can be especially problematic. We present a new approach to dealing with streamsurfaces that occlude major parts of the system representation. Analyzing mixed-mode oscillations, which are a special class of analytically defined dynamical systems, we came across geometrically complex streamsurfaces with curly shape. Certain regions of these surfaces, that are necessary to describe the behavior of the system, occlude major parts of the model. We combined and adopted several visualization techniques to deal with this problem. Streamarrows, which are semi-transparent portions of the streamsurface, allow the viewer to see through and diminish the problem of occlusion. Cross-sections and the removal of certain portions of the model reduce occlusion as well and thus improve visual perception. Choosing the shape of an arrow for segmentation allows to visualize even more information at the streamsurface, e.g., the direction of the flow. An anisotropic spot noise texture is further used to emphasize flow within a streamsurface. Finally animation techniques were applied to facilitate the interpretation of dynamical systems with complex shaped streamsurfaces.

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@techreport{loeffelmann-1996-SVM,
  title =      "Streamarrows: Visualizing Multiple Layers of
                Streamsurfaces",
  author =     "Helwig L{\"o}ffelmann and Lukas Mroz and Meister Eduard
               Gr{\"o}ller and Werner Purgathofer",
  year =       "1996",
  abstract =   "Occlusion is a crucial spatial cue for the human visual
               system. Painters as well as researchers in the field of
               computer graphics have been dealing with this aspect for a
               long time. In the field of visualization occlusion can be
               especially problematic. We present a new approach to dealing
               with streamsurfaces that occlude major parts of the system
               representation. Analyzing mixed-mode oscillations, which are
               a special class of analytically defined dynamical systems,
               we came across geometrically complex streamsurfaces with
               curly shape. Certain regions of these surfaces, that are
               necessary to describe the behavior of the system, occlude
               major parts of the model.  We combined and adopted several
               visualization techniques to deal with this problem.
               Streamarrows, which are semi-transparent portions of the
               streamsurface, allow the viewer to see through and diminish
               the problem of occlusion.  Cross-sections and the removal of
               certain portions of the model reduce occlusion as well and
               thus improve visual perception.  Choosing the shape of an
               arrow for segmentation allows to visualize even more
               information at the streamsurface, e.g., the direction of the
               flow.  An anisotropic spot noise texture is further used to
               emphasize  flow within a streamsurface.  Finally animation
               techniques were applied to facilitate the interpretation of
               dynamical systems with complex shaped                
               streamsurfaces.",
  address =    "Favoritenstrasse 9-11/186, A-1040 Vienna, Austria",
  institution = "Institute of Computer Graphics and Algorithms, Vienna
               University of Technology",
  note =       "human contact: technical-report@cg.tuwien.ac.at",
  month =      apr,
  number =     "TR-186-2-96-12",
  keywords =   "flow visualization, streamsurfaces, complex dynamical
               systems, mixed-mode oscillations",
  URL =        "http://www.cg.tuwien.ac.at/research/publications/1996/loeffelmann-1996-SVM/",
}