ENVI IDL TUTORIAL PDF
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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Note the fourth and fifth lines: The Open File dialog appears.
Titorial, 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.
When you call a user plot function, normal plot data all the spectra in the wnvi window are passed to the user plot function. For this tutorial, you will copy a previously edited version of u s e r a d d.
The following code appears in the IDL Editor: 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: Voir plus Voir moins.
This file contains the following code. Select one or more spectra; the corresponding spectral profiles appear in a Spectral Library Plots window. A Spectral Library Input File dialog appears. The plot function is applied to the data, and the resulting data are returned to the plot window where they are displayed. Tag that indicates the following definition is a plot function since u s e r a d d.
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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. ENVI calculates the second derivative spectra of all plots and displays the results in the Spectral Library Plots window.
The following steps outline this process. Sign up using Email and Password. Using the fourth field above as an yutorial, the format is as follows: Keyword variable that must be present to receive extra variables that ENVI may need to pass into the plot function.
Introduction to IDL Programming
Vector whose values identify the band positions of the bad bands in the Z Profile data. The Spectral Library Viewer dialog appears. Not sure it this will help.
On a Windows platform, this directory is in the following location where x x indicates the software version: Of course for any geospatial work outside IDL you would need to know the nominal pixel size and coordinates of at least 3 control points for image registration.
Post as a guest Name. Yudine 27 1 3. Type of plot function updates. Excluding the bad bands, the function takes the first derivative of the y value and returns it to the plot window. V Stuart Foote 5 A value of tutorail indicates that the corresponding y-axis value is good, and a value of 0 means it is bad i.
This information is often stored in a. Note that 1st Derivative will be placed immediately after the Binary Encoding menu option.
A read of Michael Todd’s above note with the link to a class exercise at UIdaho should help you with syntax of the code. Yudine, looks like you have every thing you need to read the image into an IDL array. If the plot function is defined without this keyword, then you will likely receive errors when trying to use it in ENVI.
This function accepts x and y data and a list of bad bands. A file selection dialog appears. We’ll need more info to provide a better answer. Yudine, should there be an attachement or some details? Define user plot functions by adding a new line to the useradd. Data type 2 integer probably Email Required, but never shown.