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gridding.txt
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1997-07-08
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WELCOME TO THE GRID DEMO
This demo shows the gridding of unevenly spaced data
and various interpolation methods.
A random set of data in 3D space is generated. The
Delauney triangulation method connects the data,
forming triangles. The triangulated data is then
interpolated to a location in a 3D grid. IDL offers
several interpolation techniques.
MENU OPTIONS
------------
File Menu:
Select "Quit" to exit the Grid Demo and return
to the IDL Demo main screen.
Data Menu:
Select "Generate new data" to create a new set
of random data points (X, Y, Z).
Help Menu:
Select "About interpolation and gridding" for
information about the Grid Demo.
DROPLIST FEATURE
----------------
<<X-Y point locations>>
Shows the X-Y locations of randomly-generated data
points in 3D space.
<<Delauney triangulation>>
The random data points are connected using the
Delauney triangulation method.
<<Bilinear interpolation>>
After the triangulation is performed, the data is
interpolated linearly, generating a series of flat,
interconnected surfaces. Data points located outside
the outer edges of the triangulated surface are not
interpolated. These points are assigned values
of -20.
<<Quintic interpolation>>
After the triangulation is performed, the data is
interpolated using the quintic method. Data points
located outside the outer edges of the triangulated
surface are not interpolated. These points are
assigned values of -20.
<<Smooth interpolation>>
After the triangulation is performed, the data is
interpolated using the 'Smooth' method, which
computes a boxcar average, given a width. The result
is a smooth continuous surface, without a skirt. Data
outside the triangulated surface can be extrapolated.
<<Kriging>>
Also known as 'Optimal interpolation', this method
uses an exponential scheme. It is widely accepted by
the scientific community. The result is a smooth
surface. Data outside the triangulated surface can be
extrapolated.