Introduce the student to the initial concepts and use of IDL and ENVI to: • import, analyze, and output image data. • learn to interface between ENVI input/outputs. This tutorial is designed to introduce you to the basic concepts of the ENVI software and some of its For ENVI +IDL, type envi at the UNIX command prompt. These programs (scripts) are based on the IDL programming language and are run in the IDL environment, either by loading the ENVI+IDL program or simply.
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Define user plot functions by adding a new line to the useradd.
However, while ordinary user functions are automatically called by XMANAGER and receive the event structure variable as a positional parameter, plot functions are automatically called by ENVI and receive several variables as both parameters and keywords that are related to the data in the plot window. Envk you call a user plot function, normal plot data all the spectra in the plot window are passed to the user plot function.
The plot function is applied to the data, and the resulting data are returned to the plot window where they are displayed.
The user plot function is applied to every spectrum placed in that window until a different plot function is selected. All user plot functions must have the following function definition statement: Vector whose values identify the band positions of the bad bands in the Z Profile data. This applies only to Z Profile windows and will be undefined for all other plot windows. Vector of ones and zeros with as many elements as x-axis data points. A value of 1 indicates that the corresponding y-axis value is good, and ejvi value of 0 means it is bad i.
Keyword variable that must be present to receive extra variables that ENVI may need to pass into the plot function.
If the plot function is defined without this keyword, then you will likely receive errors when trying to use it in ENVI. The Open File dialog appears. The following code appears in the IDL Editor: This function accepts x and y data and a list of bad bands.
Tutoria the bad bands, the function takes the first derivative of the y value and returns it to the plot window.
When you understand how these functions work, close the files. For this tutorial, you will copy a previously edited version of u s e r a d d.
remote sensing – Reading BSQ file format in IDL? – Geographic Information Systems Stack Exchange
The following steps outline this process. A file selection dialog appears. This file contains the following code. Note the fourth and fifth lines: Using the fourth field above as an example, the format is as follows: Tag that indicates the following definition is a plot function since u s e r a d d.
Note that 1st Derivative will be placed immediately after the Binary Encoding menu option.
ENVI Tutorial – ITT Visual Information Solutions – Informatique
Type of plot function updates. On a Windows platform, this directory is in the following location where x x indicates the software version: A Spectral Library Input File dialog appears. The Spectral Library Viewer dialog appears. Select one or more spectra; the corresponding spectral profiles appear in a Spectral Library Plots window.
ENVI calculates the first derivative spectra of all plots and displays the results in the Spectral Library Plots window. ENVI calculates the second derivative spectra of all plots and displays the results in the Spectral Library Plots window. Documents Ressources professionnelles Informatique. Voir plus Voir moins.