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iTool User's Guide: Working with Contours |
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The iContour tool's primary purpose is to display contours, though the tool is capable of much more once the data is displayed. The iContour tool can display regular-grid data or irregular-grid data. Gridding is the creation of uniformly-spaced planar data from data points. These points may initially be irregular.
Regular-grid data points are presented by two-dimensional arrays. The following example shows one way of importing and displaying this type of data into the iContour tool. The 248-by-248 two-dimensional array contained within the convec.dat
binary file in the examples/data
directory is imported into IDL with the READ_BINARY function. The iContour tool then displays this data as contours.
At the IDL Command Line, enter:
file = FILEPATH('convec.dat', SUBDIRECTORY = ['examples', 'data']) data = READ_BINARY(file, DATA_DIMS = [248, 248]) iContour, data
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Note The examples/data directory of your IDL 6.3 distribution contains a text file named index.txt . This file lists all data files available in the example directory and also lists their dimensions and values. |
Irregular-grid data points are presented by three one-dimensional vectors, usually known as fields. The following example shows one way of importing and displaying this type of data into the iContour tool. The three fields contained within the irreg_grid1.txt
ASCII file in the examples/data
directory is imported into IDL with the File Open option in the iContour tool. This option uses the ASCII Template wizard to import the data, which is then gridded into contour data with the Gridding Wizard. The iContour tool then displays this data as contours.
ICONTOUR
irreg_grid1.txt
file in the example/data
directory. The ASCII Template wizard will appear.
The irreg_grid1
file contains three columns of data points. These columns represent the x-locations, y-locations, and the elevation (respectively) of this data. These columns are specified as three fields (vectors) of data with the ASCII Template wizard.
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The IDL iTools Create Visualization dialog contains the following choices:
The Gridding Wizard allows you to specify the method of gridding while showing you the possible results for that method. The IDL Gridding Wizard Step 1 of 3 dialog contains the following items:
The IDL Gridding Wizard Step 2 of 3 dialog contains the following items:
The IDL Gridding Wizard Step 3 of 3 dialog contains the following items:
IDL Online Help (March 01, 2006)