6' VISUALIZATION of DATA 2D

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6. VISUALIZATION of DATA (2-D 3-D)
SoftwaresGRAPHER (2-D)SURFER (3-D)
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IN-CLASS PROBLEM SESSION 4

• Objective Learning repetitive execution, a
  numerical method
• (Numerical Integration of Functions) and a tool
  for the visualization of
• 2-D data (GRAPHER)
• Assignment
• Step 1 Write a program to approximate the
  integral of a given
• function over the interval (a,b) by using the
  rectangle method
• with altitudes chosen at the midpoints of the
  subintervals.
• Choose a, b and subinterval as 0., 5. and 0.5.
• Step 2 Write the numerical values of x and yx21
  calculated at Step 1
• into a previously opened file (.dat) as the
  formatted output data.
• Then plot x versus y values in .dat file by
  using GRAPHER software.

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IN-CLASS PROBLEM SESSION 6

• Objective Learning a tool for visualization of
  3-D data
• (SURFER)
• Assignment Contour the elevation values (3rd
  column)
• at x and y coordinates (1st and 2nd columns) in
  given
• 3-D data (elevation_3d.dat) by using SURFER
  program.
• Analysis the gridding methods defined in the
  surfer
• program in terms of their performances and
  problems.

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The data (elevation_3d.dat) is from Davis,1986, p
361.
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Triangulation method of estimating positions of
contour lines (Davis, 1986, p 357)
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Gridding Method Triangulation (Davis, 1986, p
364).
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Contour map by triangulation (Davis, 1986, p 365)
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Reference Davis, J. C. 1986, Statistics and
DataAnalysis in Geology, John Wiley and Sons.
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SURFER

• Surfer is a grid based contour program.
• Gridding is the process of using original data
  points
• (observations) in an XYZ data file to generate
  calculated data
• points on a regularly spaced grid (a grid file,
  .grd).
• Interpolation schemes estimate the value of the
  surface at
• locations where no original data exists, based on
  the known
• data values (observations).
• Surfer then uses the grid to generate the contour
  map or
• surface plot.

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• Under most circumstances, there are few problems
  when using
• a grid file to produce a contour map versus
  using the original raw
• data to produce the contour map.
• Surfer Gridding (Golden Software)
• http//www.seismo.unr.edu/ftp/pub/louie/class/333/
  contour/surfer.pdf
• Spatial Aliasing
• http//www.seismo.unr.edu/ftp/pub/louie/class/333/
  contour/lab.html
• Sample Gridding Methods
• http//www.colorado.edu/geography/gcraft/warmup/aq
  uifer/jpghtml/methods.html