org.orekit.propagation.events

Class GroundFieldOfViewDetector

java.lang.Object

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

org.orekit.propagation.events.GroundFieldOfViewDetector

All Implemented Interfaces:

Serializable, EventDetector

public class GroundFieldOfViewDetector
extends AbstractDetector<GroundFieldOfViewDetector>

Finder for satellite entry/exit events with respect to a sensor Field Of View attached to an arbitrary frame.

If you only want to compute access times then you should probably use ElevationDetector.

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, Evan Ward

See Also:

Propagator.addEventDetector(EventDetector), FieldOfViewDetector, ElevationDetector, Serialized Form

Field Summary

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

DEFAULT_MAX_ITER, DEFAULT_MAXCHECK, DEFAULT_THRESHOLD

Constructor Summary

Constructors

Constructor and Description
GroundFieldOfViewDetector(Frame frame, FieldOfView fov) Build a new instance.

Method Summary

Modifier and Type	Method and Description
protected GroundFieldOfViewDetector	create(double newMaxCheck, double newThreshold, int newMaxIter, EventHandler<? super GroundFieldOfViewDetector> newHandler) Build a new instance.
double	g(SpacecraftState s) Compute the value of the switching function.
FieldOfView	getFieldOfView() Get the Field Of View.
Frame	getFrame() Get the sensor reference frame.

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

GroundFieldOfViewDetector

public GroundFieldOfViewDetector(Frame frame,
                                 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:

frame - the reference frame attached to the sensor.

fov - Field Of View of the sensor.

Method Detail

create

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

Build a new instance.

Specified by:

create in class AbstractDetector<GroundFieldOfViewDetector>

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

getFrame

public Frame getFrame()

Get the sensor reference frame.

Returns:

the reference frame attached to the sensor.

getFieldOfView

public FieldOfView getFieldOfView()

Get the Field Of View.

Returns:

Field Of View

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 angular offset between the satellite and the Field Of View boundary. It is negative if the satellite is visible within the Field Of View and positive if it is outside of the Field Of View, including the margin.

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

Specified by:

g in interface EventDetector

Specified by:

g in class AbstractDetector<GroundFieldOfViewDetector>

Parameters:

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

Returns:

value of the switching function

Throws:

OrekitException - if some specific error occurs