:orphan:

.. ****************************************************************************
.. CUI
..
.. The Advanced Framework for Simulation, Integration, and Modeling (AFSIM)
..
.. The use, dissemination or disclosure of data in this file is subject to
.. limitation or restriction. See accompanying README and LICENSE for details.
.. ****************************************************************************

.. _field_of_view_commands:

Field of View Commands
----------------------

.. parsed-literal::

   field_of_view :ref:`<field-of-view-type> <field_of_view_commands.available_field_of_views>`
      ... :ref:`Type Commands <field_of_view_commands>` ...
   end_field_of_view
   
Field of views specify geometrical limits to determine if a subsystem can potentially interact with another object.  Field of views are valid for anything that uses an electromagnetic antenna, including :command:`_.transmitter`, :command:`_.receiver`.

*<field-of-view-type>* can be:

.. include:: field_of_view_types.txt

Each type have their own unique input keywords.

.. _field_of_view_commands.available_field_of_views:

Available Fields of View
========================

.. _field_of_view_commands.rectangular:

.. block:: field_of_view

rectangular
^^^^^^^^^^^

.. parsed-literal::

  field_of_view rectangular
     azimuth_field_of_view_ <angle-value> <angle-value>
     elevation_field_of_view_ <angle-value> <angle-value>
  end_field_of_view

.. block:: field_of_view.rectangular

Defines a field of view with azimuth and elevation extents.

.. command:: azimuth_field_of_view <angle-value> <angle-value>
   
   Specify the minimum and maximum angle about which the subsystem can see in azimuth.  The limits are with respect to the
   current cue.  In general these values should be greater than or equal to the :command:`_.antenna_commands.azimuth_scan_limits` (possibly
   accounting for the width of the beam when the subsystem is positioned to its scan limit).
   
   **Default** -180.0 degrees to 180 degrees
      
   .. note::
      These values are used only for initial screening to determine if the object can potentially interact with another
      object.

.. command:: elevation_field_of_view <angle-value> <angle-value>
   
   Specifies the minimum and maximum angle about which the subsystem can see in elevation.  The limits are with respect to
   the current cue.  In general these values should be greater than or equal to the :command:`_.antenna_commands.azimuth_scan_limits` (possibly
   accounting for the width of the beam when the subsystem is positioned to its scan limit).
   
   **Default** -90.0 degrees to 90 degrees

   .. note::
      This is the default field of view type.

.. _field_of_view_commands.circular:

.. block:: field_of_view

circular
^^^^^^^^

.. parsed-literal::

  field_of_view circular
     half_angle_ <angle-value>
  end_field_of_view

.. block:: field_of_view.circular

Defines a field of view that is circular, defining a conical solid angle.

.. command:: half_angle <angle-value>

   Specify the half angle from the center to the edge of the circle that the subsystem can see.

.. _field_of_view_commands.polygonal:

.. block:: field_of_view

polygonal
^^^^^^^^^

.. parsed-literal::

  field_of_view polygonal
     azimuth_elevation_ <angle-value> <angle_value>  # 1st point
     azimuth_elevation_ <angle-value> <angle_value>  # 2nd point
     azimuth_elevation_ <angle-value> <angle_value>  # 3rd point
     ...
     azimuth_elevation_ <angle-value> <angle_value>  # nth point
  end_field_of_view

.. block:: field_of_view.polygonal

Defines a field of view that is polygonal, as defined by a series of azimuth_elevation_ values from the eyepoint.  At least three values are required.

.. command:: azimuth_elevation <angle-value> <angle-value>

   Specify the az and el values to a point defining the polygonal field of view.

.. _field_of_view_commands.equatorial:

.. block:: field_of_view

equatorial
^^^^^^^^^^

.. parsed-literal::

  field_of_view equatorial
     equatorial_field_of_view_ <angle-value> <angle-value>
     polar_field_of_view_ <angle-value> <angle-value>
  end_field_of_view

.. block:: field_of_view.equatorial

Defines a field of view that is rectangular but, unlike the :ref:`rectangular field of view<field_of_view_commands.rectangular>`,
has as its sphere of orientation a celestial sphere with equator matching the earth's projected, instantaneous equator,
rather than a celestial sphere with equator matching the local horizon (i.e., the North-East plane in the local North-East-Down coordinate system).  The difference between
an equatorial field of view and similarly defined rectangular field of view is a rotation by the parallactic angle about the sensor's pointing direction.

.. command:: equatorial_field_of_view <angle-value> <angle-value>
   
   Specify the minimum and maximum angle about which the subsystem can see in the equatorial coordinate (azimuthal angle of the equatorial celestial sphere).
   The limits are with respect to the current cue.
   
   **Default** -180.0 degrees to 180 degrees
      
   .. note::
      These values are used only for initial screening to determine if the object can potentially interact with another
      object.

.. command:: polar_field_of_view <angle-value> <angle-value>
   
   Specifies the minimum and maximum angle about which the subsystem can see in the polar coordinate (polar angle of the equatorial celestial sphere).
   The limits are with respect to the current cue.
   
   **Default** -90.0 degrees to 90 degrees