Package org.orekit.propagation.events

Class CircularFieldOfViewDetector

java.lang.Object

org.orekit.propagation.events.AbstractDetector<CircularFieldOfViewDetector>

org.orekit.propagation.events.CircularFieldOfViewDetector

All Implemented Interfaces:

Serializable, EventDetector

public class CircularFieldOfViewDetector
extends AbstractDetector<CircularFieldOfViewDetector>

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 calling AbstractDetector.withHandler(EventHandler) after construction.

Author:

Véronique Pommier-Maurussane

See Also:

Propagator.addEventDetector(EventDetector), FieldOfViewDetector, Serialized Form

Field Summary

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

DEFAULT_MAX_ITER, DEFAULT_MAXCHECK, DEFAULT_THRESHOLD

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method	Description
protected CircularFieldOfViewDetector	create(double newMaxCheck, double newThreshold, int newMaxIter, EventHandler<? super CircularFieldOfViewDetector> newHandler)	Build a new instance.
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 .

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

eventOccurred, getHandler, getMaxCheckInterval, getMaxIterationCount, getThreshold, init, isForward, resetState, withHandler, withMaxCheck, withMaxIter, withThreshold

Methods inherited from class java.lang.Object

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

Constructor Detail

CircularFieldOfViewDetector

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

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:

maxCheck - maximal interval in seconds

pvTarget - Position/velocity provider of the considered target

center - Direction of the FOV center, in spacecraft frame

halfAperture - FOV half aperture angle

Method Detail

create

protected CircularFieldOfViewDetector create(double newMaxCheck,
                                             double newThreshold,
                                             int newMaxIter,
                                             EventHandler<? super CircularFieldOfViewDetector> newHandler)

Build a new instance.

Specified by:

create in class AbstractDetector<CircularFieldOfViewDetector>

Parameters:

newMaxCheck - maximum checking interval (s)

newThreshold - convergence threshold (s)

newMaxIter - maximum number of iterations in the event time search

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

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

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.

The 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<CircularFieldOfViewDetector>

Parameters:

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

Returns:

value of the switching function

Throws:

OrekitException - if some specific error occurs