System Requirements

Operating Systems

The DIRSIG software is distributed for the following platforms:

  • The Windows platform

    • OS: Windows XP, Windows 2000, Windows Vista, Windows 7, Windows 8 and Windows 10

    • Processor: x86 64-bit

    • Format: Windows MSI installer (.msi)

  • The Linux platform

    • OS: Any 2.6 or later kernel

    • Processor: x86 64-bit

    • Format: tar+gzip archive (.tgz)

  • The Mac OSX platform

    • OS: 10.6 (Snow Leopard), 10.7 (Lion), 10.8 (Mountain Lion), 10.9 (Mavericks), 10.10 (Yosemite) and 10.11 (El Capitan)

      • Installation currently requires Gatekeeper to allow applications downloaded from "Anywhere"

    • Processor: x86 64-bit

    • Format: Disk image (.dmg) containing the software as a folder to be copied into the system Applications folder or user folder.

Hardware Requirements

The following hardware recommendations:

  • A recent CPU (e.g. Intel Core 2 family, AMD Athlon family) with clock rates of 2 GHz or higher.

  • At least 2 GB of memory (RAM).

  • At least 2 GB of disk space.

    • The user should expect to use significantly more disk space when they begin to generate data with the model.

  • There is no minimum requirement for video cards and displays.

    • Any display hardware that would be present in the previously outlined machine tends to be sufficient.

Software Requirements

The following software is required:


    • Either a copy of MODTRAN4 or MODTRAN5 is required for rigorous atmospheric modeling

      • MODTRAN4 Version 3 Release 1 or later

      • MODTRAN5 2.0.0 or later

    • Visit for more information on how to obtain a copy of MODTRAN5

The DIRSIG software comes with a built-in image viewer, however the following software is recommended:

  • A copy of an image exploitation tool such as ENVI or Opticks can provide advanced image/data viewing and analysis of the image files produced by DIRSIG.

  • A copy of a LIDAR exploitation tool such as MARS FreeView or QuickTerrain Reader can provide advanced viewing and analysis of LAS format 3D point clouds produced by DIRSIG.

Execution Requirements

The following clarifications might be useful to system administrators:

  • DIRSIG does not need "administrator" privilages to run. The end user simply needs:

    • Execute permissions for the programs, and

    • Read-only access to the support files included in the installation.

  • DIRSIG does not have any "phone home" mechanisms (for example, to check for software updates)

    • The default option is to use the HTML documentation installed with the software. However the end-user can change that to access the HTML documentation source on the DIRSIG website.


A standard DIRSIG release contains the following:

  • A set of executable programs

  • A collection of HTML-formatted support documents

  • A set of demonstration (example) simulations

  • A set of examples scenes

    • The "Forest" scene

    • The "Foxbat" scene

    • The "Refinery" scene

    • The "Urban" scene

    • The "Warehouse" scene

  • A folder of "extras" that include Matlab and Blender scripts for various tasks.


The DIRSIG software is released on the Windows platform as a traditional Windows installer (with a .msi extension). Simply double-click the installer file and follow the standard directions to install the software.

The default install location for DIRSIG is the C:\Program Files\DIRSIG 4 folder.


The DIRSIG4 software for the LINUX platform is released as a tar+gzip archive that contains the program executables, supplemental data, basic scenes, etc. The installation of the software is as simple as choosing a location, unpacking the archive into that location, and setting up your user environment.

There are no requirements or assumptions about where the DIRSIG installation will be located. An administrator with the correct permissions can install DIRSIG in a common area (for example, /usr/local or /opt) so that multiple users can access the single installation. A single user without special permissions can install DIRSIG in a directory in their account.

For the remainder of this explanation, we will assume that the DIRSIG software will be installed in /opt/rit/dirsig (which will most likely require superuser permissions) and that the DIRSIG installation archive file is located in the /tmp (the user can obviously adapt these instructions to deal with the installation destination or source archive file being in any location).

Note The choice of /opt/rit/dirsig as the installation folder is just an example. Any acessible folder is valid.

To create the installation directory, execute the following command:

$ mkdir /opt/rit/dirsig

Then, make sure you are at the top of your installation directory:

$ cd /opt/rit/dirsig

Then unpack the DIRSIG installation archive. On the LINUX platform this can be done using the tar command (which has gzip compression support built-in):

$ tar -xzvf /tmp/dirsig-4.7.0-Linux-2.6-x86_64.tgz

The name of the DIRSIG executables on the Linux platform have the release name appended to them. For example, the main DIRSIG program in the 4.7.0 release is named dirsig_edit-4.7.0. The installing user has two (2) choices regarding the default executable names:

  • Keep the default executable names and instruct the users that executables need to be accessed with the release appended to them.

    • Users then have the option to add personal aliases to access dirsig_edit-4.7.0 as simply dirsig_edit.

  • Keep the default executable names and make a set of symbolic links to each program with simpler names.

    • For example, make a link named dirsig_edit that points to dirsig_edit-4.7.0.


The DIRSIG software is released on the Mac OSX platform as a traditional installer "package" within a disk image. The software is installed like most software:

  • Mount the disk image by double-clicking on the .dmg file.

  • Open the mounted disk image in Finder (it should have appeared as a new volume after you mounted it).

  • Drag the DIRSIG4 folder into the system Applications folder (which will require admin privileges), the user’s Applications folder, or any accessible folder.

  • If you plan on using DIRSIG via the command-line, then you will need to modify your login files to include the DIRSIG4/bin folder.


This section outlines the process to upgrade an existing DIRSIG installation to a newer release.

Important If you are upgrading from DIRSIG 4.4 or earlier, it is strongly recommended that you uninstall DIRSIG prior to installing DIRSIG 4.5 or later.
Important If you are upgrading from DIRSIG 4.4 or earlier, Mac OSX users should delete the DIRSIG_HOME key/string pair from your ~/.MacOSX/environment.plist file (which is no longer required). This task can be performed with a .plist file capable editor such as TextWrangler or Xcode.
Tip The default behavior of most installers is to replace a previous installation with the new version. If you want to keep a copy of the previous version when you install a new version, the best approach is to make a copy of the installation prior to installing the new version.


The .msi installer can be run directly as outlined in the Installation section above. Installing an update will replace the previous version of DIRSIG.


There are several ways to manage upgrades of the DIRSIG software on Linux.

Overlaid Installations

If you unpack release 4.7.1 in the same directory as 4.7.0, all the files from 4.7.0 will be replaced by 4.7.1 except the executables. That is because the executables have the release appended to them. In this case, you would finish with dirsig-4.7.0 and dirsig-4.7.1. This has the advantage of providing the end-user with the option to downgrade to the previous version by simply running a different executable. However, the installing user will want to manually purge the older executables from previous versions over time to avoid having executables from previous releases installed.

Parallel Installations

The other option for upgrades is to create a whole new installation directory for each installation. In this approach, rather than installing to /opt/rit/dirsig, the installer might unpack into /opt/rit/dirsig-4.7.0. When the 4.7.1 release arrives, the installer can unpack that release into /opt/rit/dirsig-4.5.1. To simplify this scheme for users, you might consider making a symbolic link called /opt/rit/dirsig that always points to the current installation directory. Again, the installing user will want to purge old installation folders over time.


To keep an previous version of the software, the proces is straightforward. Since the installation is a simple drag and drop process, the user can rename an older installation folder (for example, DIRSIG4DIRSIG-4.6.3) prior to copying the new version.

Using the Software

First time users will be greeted with the DIRSIG User Setup Wizard the first time they start the graphical user interface. This wizard will guide them through the process of setting up their personal settings, including telling DIRSIG where MODTRAN is installed. More information about setting up DIRSIG to use MODTRAN is discussed below.


Starting in DIRSIG 4.5, information required by DIRSIG to locate and run MODTRAN is stored in each user’s personal settings. This new method allows each user to configure multiple MODTRAN installations, and then select which MODTRAN installation is used during a given simulation.

Note A given user’s list of MODTRAN installation profiles might include stable versus experimental versions of MODTRAN.

First time DIRSIG users will be prompted by the DIRSIG User Setup Wizard to configure a MODTRAN installation profile. In addition, users can always add, remove or modify a MODTRAN installation profile via MODTRAN tab in the Preferences window for the user interface.

Each installation profile requires three pieces of information:

  • The path to the MODTRAN executable file

  • The path to the MODTRAN DATA folder

  • The minimum spectral delta supported by that version

    • This is 1 wavenumber (1/cm) for MODTRAN4 and 0.1 wavenumber (1/cm) for MODTRAN5

Important The standard Windows distribution of MODTRAN5 can contain two executables: one ending with qwin.exe and one ending with cons.exe. You must select the _cons.exe version (which is a "console only" application suitable for being called by other programs) for use with DIRSIG.
Important The standard Mac OSX distribution of MODTRAN5 has dependencies on dynamic libraries that are included with the distribution. However, to run MODTRAN5 from outside the installation folder (which is required by DIRSIG), then you should consult this note.

If you are having problems with DIRSIG integrating with MODTRAN, consult the Troubleshooting MODTRAN issues document.

Command-Line Usage

DIRSIG is distributed with a graphical user interface (GUI) that allows the user to configure and run a DIRSIG simulation without using any command-line tools. However, there are still many reasons you might want to run a DIRSIG simulation from the command-line. To learn more about the command-line aspects of the model, consult the DIRSIG command-line usage guide.


The Windows installer should have automatically added the folder containing the DIRSIG executables to the path used in the CMD window.

Linux and Mac OSX

If you want to run DIRSIG from the command line then your login shell will need to have the path to the DIRSIG executables configured. The default shell for many accounts on Linux is bash, but many users use csh or tcsh. The automatic setup of environment variables in your login shell is slightly different for each shell, but the general requirements for each are the same. If you are a novice at setting up your shell environment, consult the documentation for the shell you are using or ask an experienced user or administrator.