This manual was written to help new and experienced users make use of the DIRSIG modeling software. This model is a complex collection of engineering and scientific models that can be used to created synthetic imagery, create look-up tables for algorithms, etc. Due to it's complexity, there is a lot of material to explain to a user. In addition, there is a very diverse set of users that will make use of this manual and each will have a different level of understanding for each topic.
The manual has been divided into four logical sections or parts:
The "Introduction" introduces some of the technical aspects of the model including theory and equations. It also includes the directions for installing the software and a Getting Started chapter to get the user familiarized with the software at the top level.
The "In-Depth Material" material discusses some of the more complex aspects of the model in greater depth.
The "DIRSIG4 Features" describe various aspects of additional programs that are supplied with the DIRSIG model as support tools.
The "Support Application Manuals" sections describe important aspects including the formats of files created and used by the model.
Each of of the chapters in the manual follow the same general organization and layout. This allows the user to navigate the documentation based on the material that they are most interested in learning more about. This layout is described below using the in-depth area of Atmospheric Modeling as an example:
An "overview" section provides a general overview of the topic area. In this case, the role of the atmosphere in the modeling process is explained at a high level.
The "theory" or "technical" section introduces the scientific theory used in the modeling approach associated with this topic. In the case of the atmosphere, it describes how the atmosphere is modeled using MODTRAN generated look-up tables.
The "how-to" section introduces the various DIRSIG related variables, user-interfaces and related input files related to the topic. This section is usually reference oriented so that experienced users can return to it to find related information. For the atmospheric modeling topic, this section describes how the atmospheric database is supplied to the model, related options, etc.
The "tutorials" section will contain one or more step-by-step mini tutorials that guide the user through the configuration of aspects of the model related to the topic. These mini tutorials do not cover how to set-up an entire simulation. Instead, the focus is on providing a step-by-step reference for configuring aspects of the specific topic. For example, in the atmospheric modeling chapter, the tutorials guide the user through the configuration of a few example atmospheres.
A "troubleshooting tips" section is also usually included which will discuss specific problems that commonly arise. In the case of atmospheric modeling, this section discusses common errors that are produced by MODTRAN or the DIRSIG make_adb utility.
The "frequently asked questions" or FAQ section contains short answers to commonly asked questions. It is not intended to be a one-stop reference to any question regarding the model or the topic. If your questions is more complex, consult the "how-to" or "troubleshooting tips" sections.