Issues installing ENVI 4.8 onto IDL 8.0.1 in Windows

THIS INFORMATION ONLY PERTAINS TO SOFTWARE VERSIONS IDL 8.5, ENVI 5.3 AND PRIOR

Topic

When attempting to install ENVI 4.8 in a Windows operating system, it will be necesary to understand what it's already installed before proceeding.

There are four possible scenarios:

1- Installing ENVI 4.8 over IDL 8.0 and then adding the IDL 8.0.1 patch: this will work.
2- Having ENVI 4.8, with no IDL 8.0 installed, and then adding IDL 8.0 and the patch: this will work.
3- Installing ENVI 4.8 over IDL 8.0.1: ARROW() function will fail to work.
4- Installing ENVI 4.8 and then adding the IDL 8.0.1 patch: it will break IDL Workbench completely.

 

Discussion

In this article we would like to explore the different installation scenarios under Windows operating system, that a user can encounter when installing ENVI 4.8.

In Windows systems, ENVI 4.8 includes, in its installation, a version of the IDL 8.0 patch (8.0.1) that is different from the one shipped in the stand-alone IDL 8.0.1 installation. Because of that users would like to install the stand-alone version of the patch, but they will need to be aware of the order in which ENVI and IDL versions are installed in their systems.

What follows is a description of four difference installation scenarios, describing potential problems in some of those cases:

1. Order of Installation: IDL 8.0 - ENVI 4.8 - IDL 8.0.1 patch
   
   If the ENVI user has already installed in his/her Windows system IDL 8.0, but the IDL 8.0.1 patch is not yet installed, then the following order of installation will ensure that all the patch functionalities will work correctly:
   
   A- IDL 8.0 is installed in your system.
   B- install ENVI 4.8
   C- install IDL 8.0.1 patch
   
   

2. Order of Installation: ENVI 4.8 - IDL 8.0 - IDL 8.0.1 patch
   
   In this case scenario, ENVI 4.8 is installed first, without having IDL 8.0. Then, IDL 8.0 + the IDL 8.0.1 patch are installed. This order of installation will also ensure that all the patch functionalities will work correctly:
   
   A- Install ENVI 4.8
   B- Install IDL 8.0
   C- Install IDL 8.0.1 patch
   
   

3. Order of Installation: IDL 8.0.1 patch - ENVI 4.8
   
   In this scenario, IDL 8.0 + 8.0.1 path are already installed in the system. Then, ENVI 4.8 is installed on top of the stand-alone IDL patch. This order will break some of the new functionalities included in the "stand-alone" version of the IDL patch. One of the symptoms that a user will notice is, for example, the ARROW function will fail to work. The following is the error message that a user will get when trying to execute the ARROW function:
   
   p=plot(/test)
   s=[0., 50.]
   e=[-.5,.5]
   a=arrow(s, e,TARGET=p, /data)

   
   
   

   % Unable to invoke method on NULL object reference: )>. % Error occurred at: ARROW 22 C:\Program Files\ITT\IDL\IDL80\lib\graphics\graphic_error.pro % $MAIN$ % Execution halted at: $MAIN$

   But most of IDL 8.0.1 will continue working as before, and only if the user needs to run the ARROW function will be necessary to go through the process of un-installing ENVI 4.8 and then follow the order given in point 1 of this article.
   
   

4. Order of Installation: IDL 8.0 - IDL 8.0.1 patch - ENVI 4.8 - IDL 8.0.1 patch
   
   In this case, "re-installing" the IDL 8.0.1 patch after having ENVI 4.8 installed over the same patch will completely break the whole IDL 8.0 installation and workbench. The symptoms are the following:
   
   A- The top Workbench action bottoms will not be shown, ie. that part of the workbench will be empty.
   B- The whole IDL command line plus console window will be gone.
   
   This scenario implies that the user will have to un-install ENVI and IDL and will have to follow the installation order lay out in point one of this article.

Note: Un-installing ENVI 4.8 might take several minutes to complete.