Package org.orekit.propagation.events

Class FieldOfViewDetector

java.lang.Object
org.orekit.propagation.events.AbstractDetector<FieldOfViewDetector>
org.orekit.propagation.events.FieldOfViewDetector
All Implemented Interfaces:
EventDetector
public class FieldOfViewDetector extends AbstractDetector<FieldOfViewDetector>
Finder for target entry/exit events with respect to a satellite sensor Field Of View.

Beware that this detector is unaware of any bodies occluding line-of-sight to the target. It can be therefore used for many contexts from Earth Observation to interplanetary mission design. For instance, in an Earth Observation context, it can be easily combined to an ElevationDetector using BooleanDetector.andCombine(java.util.Collection) to calculate station visibility opportunities within the satellite's field of view.

The default implementation behavior is to continue propagation at FOV entry and to stop propagation at FOV exit. This can be changed by calling AbstractDetector.withHandler(EventHandler) after construction.

Since:
7.1
Author:
Luc Maisonobe
See Also:

  • Constructor Details

    • FieldOfViewDetector

      public FieldOfViewDetector(PVCoordinatesProvider pvTarget, FieldOfView fov)
      Build a new instance.

      The maximal interval between distance to FOV boundary checks should be smaller than the half duration of the minimal pass to handle, otherwise some short passes could be missed.

      Parameters:
      pvTarget - Position/velocity provider of the considered target
      fov - Field Of View
      Since:
      10.1

    • FieldOfViewDetector

      public FieldOfViewDetector(PVCoordinatesProvider pvTarget, double radiusTarget, VisibilityTrigger trigger, FieldOfView fov)
      Build a new instance.

      The maximal interval between distance to FOV boundary checks should be smaller than the half duration of the minimal pass to handle, otherwise some short passes could be missed.

      Parameters:
      pvTarget - Position/velocity provider of the considered target
      radiusTarget - radius of the target, considered to be a spherical body (m)
      trigger - visibility trigger for spherical bodies
      fov - Field Of View
      Since:
      10.1

    • FieldOfViewDetector

      protected FieldOfViewDetector(EventDetectionSettings detectionSettings, EventHandler handler, PVCoordinatesProvider pvTarget, double radiusTarget, VisibilityTrigger trigger, FieldOfView fov)
      Protected constructor with full parameters.

      This constructor is not public as users are expected to use the builder API with the various withXxx() methods to set up the instance in a readable manner without using a huge amount of parameters.

      Parameters:
      detectionSettings - detection settings
      handler - event handler to call at event occurrences
      pvTarget - Position/velocity provider of the considered target
      radiusTarget - radius of the target, considered to be a spherical body (m)
      trigger - visibility trigger for spherical bodies
      fov - Field Of View
      Since:
      13.0

  • Method Details

    • create

      protected FieldOfViewDetector create(EventDetectionSettings detectionSettings, EventHandler newHandler)
      Build a new instance.
      Specified by:
      create in class AbstractDetector<FieldOfViewDetector>
      Parameters:
      detectionSettings - detection settings
      newHandler - event handler to call at event occurrences
      Returns:
      a new instance of the appropriate sub-type

    • getPVTarget

      public PVCoordinatesProvider getPVTarget()
      Get the position/velocity provider of the target .
      Returns:
      the position/velocity provider of the target

    • getFOV

      public FieldOfView getFOV()
      Get the Field Of View.
      Returns:
      Field Of View
      Since:
      10.1

    • g

      public double g(SpacecraftState s)
      Compute the value of the switching function. This function must be continuous (at least in its roots neighborhood), as the integrator will need to find its roots to locate the events.

      The g function value is the angular offset between the target center and the Field Of View boundary, plus or minus the target angular radius depending on the VisibilityTrigger, minus the Field Of View margin. It is therefore negative if the target is visible within the Field Of View and positive if it is outside of the Field Of View.

      As per the previous definition, when the target enters the Field Of View, a decreasing event is generated, and when the target leaves the Field Of View, an increasing event is generated.

      Parameters:
      s - the current state information: date, kinematics, attitude
      Returns:
      value of the switching function