1.1 Introduction

OTB Applications was perhaps the older package of the Orfeo ToolBox suite after the OTB package itself. Since the Orfeo ToolBox is a library providing remote sensing functionalities, the only applications that were distributed at the beginning were the examples from the Software Guide and the tests. These applications are very useful for the developer because their code is very short and only demonstrates one functionality at a time. In many cases, a real application would require :

The OTB Applications package was originally designed to provide applications performing simple remote sensing tasks, more complex than simple examples from the Software Guide, and with a more user-friendly interface (either graphical or command-line), to demonstrate the use of the Orfeo ToolBox functions. The most popular applications are maybe the otbImageViewerManager, which allows to open a collection of images and navigate in them, and the otbSupervisedClassificationApplication, which allowed to delineate training regions of interest on the image and classify the image with a SVM classifier trained with these regions (this application is no longer maintained since the same functionnality is available through the corresponding Monteverdi module). During the first 3 years of the Orfeo ToolBox development, many more applications have been added to this package, to perform various tasks. Most of them came with a graphical user interface, apart from some small utilities that are command-line.

The development and release of the Monteverdi software (see chapter 2 at the end of year 2009 changed a lot of things for the OTB Applications package: most of non-developer users were looking for quite a long time for an application providing Orfeo ToolBox functionalities under a unified graphical interface. Many applications from the OTB Applications package were integrated to Monteverdi as modules, and the OTB Applications package lost a lot of its usefulness. No more applications were added to the package and it was barely maintained, as new graphical tools were directly embedded within Monteverdi.

Then, some people started to regain interest in the OTB Applications package. Monteverdi is a great tool to perform numerous remote sensing and image processing task in a minute, but it is not well adapted to heavier (and longer) processing, scripting and batch processing. Therefore, in 2010 the OTB Applications package has been revamped: old applications have been moved to a legacy folder for backward compatibility, and the development team started to populate the package with compact command-line tools to perform various heavy processing tasks.

Later on in 2011, the OTB Applications has been further revamped. Because of the increasing need to interface the OTB Applications into other software and to provide auto-generated interfaces, the Orfeo ToolBox development team decided to develop a new application framework. The main idea of this framework is the following: each application is written once for all in a shared library (also known as plugin). This plugin can be auto-loaded into appropriate tools wihtout recompiling, and is able to fully describe its parameters, behaviour and documentation.

The tools to use the plugins can be extended, but Orfeo ToolBox shipped the following:

Additionally, QGis plugins built on top of the SWIG/Python interface are available with seamless integration within QGis. You can find a short guide about it here.

To facilitate the use of these tools and applications, they will now be shipped with the standard Orfeo ToolBox package. It means that the former OTB-Applications package has entered its maintenance cycle : no new feature will be pushed there, and all development is done directly inside the Orfeo ToolBox paackage.

The OTB Applications are now rich of more than 40 tools, which are listed in the the applications reference documentation, presented in chapter 4, page 405.