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MGH_EXAMPLE_SCATTER

MGH_EXAMPLE_SCATTER

Name


  MGH_EXAMPLE_SCATTER

Purpose


  3D scatter plot example.
  For a discussion of the different representations possible for a
  3D scatter plot in object graphics see:
    http://www.sljus.lu.se/stm/IDL/misc/scatter_surface.txt
  I used this procedure to test relative times for creating & drawing
  different symbol types. In each case I used STYLE=0 (single polyline
  with a single symbol object) and N_POINTS=10000. Times for execution
  of the procedure (IDL 5.3 on Pentium II 400 MHz) were compared for
  different symbol types:
    IDLgrSymbol with DATA=6 (square): 0.78 s
    IDLgrSymbol with DATA set to a 4-vertex polyline 1.52 s
    IDLgrSymbol with DATA set to a 16-vertex polyline 1.68 s
    IDLgrSymbol with DATA set to a model containing a
    4-vertex polyline 1.91 s
    IDLgrSymbol with DATA set to a model containing a
    16-vertex polyline 2.08 s
    IDLgrSymbol with DATA set to a 4-vertex polygon 1.72 s
  Conclusions:
    - The simplest user-defined symbols (DATA = a polyline) are about
    a factor of 2 slower than the built-in symbols.
    - Drawing time increases with the number of vertices in the symbol,
    but much slower than linearly.
    - Filled symbols (polygons) are 13% slower than unfilled symbols
    (polylines).
    - The extra indirection involved with embedding the user-defined
    symbol in a model adds 25% to drawing time
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  This software is provided subject to the following conditions:
  1. NIWA makes no representations or warranties regarding the
    accuracy of the software, the use to which the software may
    be put or the results to be obtained from the use of the
    software. Accordingly NIWA accepts no liability for any loss
    or damage (whether direct of indirect) incurred by any person
    through the use of or reliance on the software.
  2. NIWA is to be acknowledged as the original author of the
    software where the software is used or presented in any form.
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Modification History


  Mark Hadfield, 2001-06:
    Written.



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