org.orekit.propagation.events
Class CircularFieldOfViewDetector

java.lang.Object
  org.orekit.propagation.events.AbstractDetector
      org.orekit.propagation.events.CircularFieldOfViewDetector

All Implemented Interfaces:

Serializable, EventDetector

public class CircularFieldOfViewDetector
extends AbstractDetector

Finder for target entry/exit events with respect to a satellite sensor field of view.

This class handle fields of view with a circular boundary.

The default implementation behavior is to continue propagation at fov entry and to stop propagation at fov exit. This can be changed by using the constructor CircularFieldOfViewDetector.

Author:

Véronique Pommier-Maurussane

See Also:

Propagator.addEventDetector(EventDetector), DihedralFieldOfViewDetector, Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from interface org.orekit.propagation.events.EventDetector

EventDetector.Action

Field Summary

Fields inherited from class org.orekit.propagation.events.AbstractDetector

DEFAULT_MAXCHECK, DEFAULT_THRESHOLD

Fields inherited from interface org.orekit.propagation.events.EventDetector

DECREASING, INCREASING, INCREASING_DECREASING

Constructor Summary

CircularFieldOfViewDetector(PVCoordinatesProvider pvTarget, Vector3D center, double halfAperture, double maxCheck)
Build a new instance.

CircularFieldOfViewDetector(PVCoordinatesProvider pvTarget, Vector3D center, double halfAperture, double maxCheck, double threshold)
Build a new instance.

CircularFieldOfViewDetector(PVCoordinatesProvider pvTarget, Vector3D center, double halfAperture, double maxCheck, double threshold, EventDetector.Action entry, EventDetector.Action exit)
Build a new instance with defined actions at fov entry and exit.

CircularFieldOfViewDetector(PVCoordinatesProvider pvTarget, Vector3D center, double halfAperture, double maxCheck, double threshold, EventDetector.Action entry, EventDetector.Action exit, boolean removeEntry, boolean removeExit)
Build a new instance with defined actions at fov entry and exit.

Method Summary

EventDetector.Action	eventOccurred(SpacecraftState s, boolean increasing, boolean forward) Handle an fov event and choose what to do next.
double	g(SpacecraftState s) Compute the value of the switching function.
Vector3D	getCenter() Get the direction of fov center.
double	getHalfAperture() Get fov half aperture angle.
PVCoordinatesProvider	getPVTarget() Get the position/velocity provider of the target .
boolean	shouldBeRemoved() This method is called after EventDetector.eventOccurred(org.orekit.propagation.SpacecraftState, boolean, boolean) has been triggered.

Methods inherited from class org.orekit.propagation.events.AbstractDetector

getMaxCheckInterval, getMaxIterationCount, getSlopeSelection, getThreshold, init, resetState

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CircularFieldOfViewDetector

public CircularFieldOfViewDetector(PVCoordinatesProvider pvTarget,
                                   Vector3D center,
                                   double halfAperture,
                                   double maxCheck)

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.

The default implementation behavior is to continue propagation at fov entry and to stop propagation at fov exit.

Parameters:

pvTarget - Position/velocity provider of the considered target

center - Direction of the fov center, in spacecraft frame

halfAperture - Fov half aperture angle

maxCheck - maximal interval in seconds

CircularFieldOfViewDetector

public CircularFieldOfViewDetector(PVCoordinatesProvider pvTarget,
                                   Vector3D center,
                                   double halfAperture,
                                   double maxCheck,
                                   double threshold)

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.

The default implementation behavior is to continue propagation at fov entry and to stop propagation at fov exit.

Parameters:

pvTarget - Position/velocity provider of the considered target

center - Direction of the fov center, in spacecraft frame

halfAperture - Fov half aperture angle

maxCheck - maximal interval in seconds

threshold - threshold in seconds for events date computation

CircularFieldOfViewDetector

public CircularFieldOfViewDetector(PVCoordinatesProvider pvTarget,
                                   Vector3D center,
                                   double halfAperture,
                                   double maxCheck,
                                   double threshold,
                                   EventDetector.Action entry,
                                   EventDetector.Action exit)

Build a new instance with defined actions at fov entry and exit.

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

center - Direction of the fov center, in spacecraft frame

halfAperture - Fov half aperture angle

maxCheck - maximal interval in seconds

threshold - threshold in seconds for events date computation

entry - action performed at fov entry

exit - action performed at fov exit

CircularFieldOfViewDetector

public CircularFieldOfViewDetector(PVCoordinatesProvider pvTarget,
                                   Vector3D center,
                                   double halfAperture,
                                   double maxCheck,
                                   double threshold,
                                   EventDetector.Action entry,
                                   EventDetector.Action exit,
                                   boolean removeEntry,
                                   boolean removeExit)

Build a new instance with defined actions at fov entry and exit.

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

center - Direction of the fov center, in spacecraft frame

halfAperture - Fov half aperture angle

maxCheck - maximal interval in seconds

threshold - threshold in seconds for events date computation

entry - action performed at fov entry

exit - action performed at fov exit

removeEntry - true if detector should be removed at fov entry

removeExit - true if detector should be removed at fov exit

Since:

3.1

Method Detail

getPVTarget

public PVCoordinatesProvider getPVTarget()

Get the position/velocity provider of the target .

Returns:

the position/velocity provider of the target

getCenter

public Vector3D getCenter()

Get the direction of fov center.

Returns:

the direction of fov center

getHalfAperture

public double getHalfAperture()

Get fov half aperture angle.

Returns:

the fov half aperture angle

eventOccurred

public EventDetector.Action eventOccurred(SpacecraftState s,
                                          boolean increasing,
                                          boolean forward)
                                   throws OrekitException

Handle an fov event and choose what to do next.

The default implementation behavior is to continue propagation at entry and to stop propagation at exit. This can be changed by using the constructor CircularFieldOfViewDetector

Specified by:

eventOccurred in interface EventDetector

Specified by:

eventOccurred in class AbstractDetector

Parameters:

s - the current state information : date, kinematics, attitude

increasing - if true, the value of the switching function increases when times increases around event, i.e. target enters the fov (note that increase is measured with respect to physical time, not with respect to propagation which may go backward in time)

forward - if true, the integration variable (time) increases during integration.

Returns:

the action performed at expected fov entry or exit.

Throws:

OrekitException - if some specific error occurs

shouldBeRemoved

public boolean shouldBeRemoved()

This method is called after EventDetector.eventOccurred(org.orekit.propagation.SpacecraftState, boolean, boolean) has been triggered. It returns true if the current detector should be removed after first event detection. WARNING: this method can be called only once a event has been triggered. Before, the value is not available.

Specified by:

shouldBeRemoved in interface EventDetector

Specified by:

shouldBeRemoved in class AbstractDetector

Returns:

true if the current detector should be removed after first event detection

g

public double g(SpacecraftState s)
         throws OrekitException

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. g function value is the difference between fov half aperture and the absolute value of the angle between target direction and field of view center. It is positive inside the fov and negative outside.

Specified by:

g in interface EventDetector

Specified by:

g in class AbstractDetector

Parameters:

s - the current state information: date, kinematics, attitude for forces and events computation, mass provider, and additional states

Returns:

value of the switching function

Throws:

OrekitException - if some specific error occurs