Visualization Techniques

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Visualization Techniques

• Dealing with your data as a volume What is the
  best way to render a volumetric data set in a
  way that makes sense to the human eye?

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Visualization Techniques

• The following is a list of basic techniques that
  you can reasonably expect to find available in
  any scientific visualization software package
• This does not cover all possible techniques!
• Introductory only, but very useful

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Viz Techniques Edges

• Exteriors and edges - Finding the boundaries of
  your data and the extents of your data space.
• Useful to see where your data should be if you
  dont see anything yet!
• In OpenDX see
• Showbox

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Viz Techniques Color

• Colors Humans are very sensitive to variations
  in color, which makes color one of the best cues
  available for information visualization. i.e. Use
  color to attach meaningful graphical cues to your
  data sets.
• LUT lookup table
• an array that holds a set of pre-computed
• results accessed by index
• a list of colors
• Colormap the complete list of color values
  placed at each index of the LUT

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Viz Techniques Annotation

• Label the visualization to provide context
• Not necessarily text

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Viz Techniques Annotation
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Viz Techniques Contours

• Contour lines connect points with the same
  elevation
• Isolines lines connecting all points having the
  same field values
• For a height field
• Contours Isolines
• Lines are frequently colored by the level value

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Viz Techniques Contours
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Viz Techniques Slices

• Slices and cross-sections - Take a cross-section
  of your volume and examine it as a separate slice
• Take a slice through any plane of the data set
• In OpenDX see
• MapToPlane

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Viz Techniques Slices
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Viz Techniques Isosurfaces

• Isosurfaces represent 3-D scalar fields by
  drawing surfaces representing constant function
  values

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Viz Techniques Isosurfaces
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Viz Techniques Glyphs

• Glyphs (Greek glyphe carving)
• small 3D objects which represent one or more data
  values at a location in space
• E.g. stick-and-ball model used by chemists in
  visualizing complex molecule structures
• - the colored balls represent individual atoms
  in the molecule, and the sticks of varying length
  stand for the bonds among the atoms.

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Viz Techniques Glyphs
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Viz Techniques Vector fields

• Vector fields - Using vector fields rather than
  solid rendering to display additional dimensions
  attached to your data.
• The vectors are arrow glyphs whose length and
  direction are provided by the vector field

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Viz Techniques Vector fields
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Viz Techniques Streamlines

• Streamlines line that is tangential to the
  instantaneous velocity direction if the field
  describes the velocity in a hydrodynamic system.
• also called a flow line or a characteristic curve
• If the field is a force field then the stream
  lines are called lines of force (think of
  electric and magnetic fields).

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Viz Techniques Streamlines
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Viz Techniques Animation

• Animation - The best visual cue of depth and time
  is one of motion.
• Single frame animation - generate a series of
  frames and convert them to an mpeg
• mpeg_encode (Berkley mpeg encoder)
• ppmtompeg (Berkley mpeg encoder distributed with
  libpbm)