Introduction
============


This chapter introduces SEXTANTE, the powerful geospatial analysis framework of QGIS.
SEXTANTE is a geoprocessing environment that can be used to call native
and third party algorithms from QGIS, making your spatial analysis tasks
more productive and easy to accomplish.

In the following sections we will review how to use the graphical
elements of SEXTANTE and take the most out of each one of them

Basic elements of the SEXTANTE GUI
----------------------------------

There are four basic elements in the SEXTANTE GUI, which are used to run
SEXTANTE algorithms for different purposes. Choosing one tool or another
will depend on the kind of analysis that is to be performed and the
particular characteristics of each user and project. All of them (except
for the batch processing interface, which is called from the toolbox, as
we will see) can be accessed from the *SEXTANTE* menu item (you will see
more than four entries. The remaining ones are not used to execute
algorithms and will be explained later in this chapter).

-  The SEXTANTE toolbox. The main element of the SEXTANTE GUI, it is
   used to execute a single algorithm or run a batch process based on
   that algorithm.

   .. figure:: toolbox.png
      :align: center
      :alt: image


-  The SEXTANTE graphical modeler. Several algorithms can be combined
   graphically using the modeler to define a workflow, creating a single
   process that involves several sub-processes

   .. figure:: models.png
      :align: center
      :alt: image


-  The SEXTANTE history manager. All actions performed using any of the
   aforementioned elements are stored in a history file and can be later
   easily reproduced using the history manager

   .. figure:: history.png
      :align: center
      :alt: image


-  The SEXTANTE batch processing interface manager. This interface
   allows you to execute batch processes and automate the execution of a
   single algorithm on multiple datasets.

   .. figure:: batch_processing.png
      :align: center
      :alt: image


Along the following sections we will review each one of this elements in
detail.
