org.orekit.propagation.events
Class DihedralFieldOfViewDetector

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

All Implemented Interfaces:

java.io.Serializable, EventDetector

public class DihedralFieldOfViewDetector
extends AbstractDetector

Finder for body entering/exiting dihedral fov events.

This class finds dihedral field of view events (i.e. body entry and exit in fov).

The default implementation behavior is to continue propagation at entry and to stop propagation at exit. This can be changed by overriding the eventOccurred method in a derived class.

Version:

$Revision: 2761 $ $Date: 2009-04-28 17:49:07 +0200 (mar., 28 avr. 2009) $

Author:

Véronique Pommier-Maurussane

See Also:

Propagator.addEventDetector(EventDetector), CircularFieldOfViewDetector, Serialized Form

Field Summary

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

DEFAULT_MAXCHECK, DEFAULT_THRESHOLD

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

CONTINUE, RESET_DERIVATIVES, RESET_STATE, STOP

Constructor Summary

DihedralFieldOfViewDetector(double maxCheck, PVCoordinatesProvider pvTarget, org.apache.commons.math.geometry.Vector3D center, org.apache.commons.math.geometry.Vector3D axis1, double halfAperture1, org.apache.commons.math.geometry.Vector3D axis2, double halfAperture2)
Build a new instance.

Method Summary

int	eventOccurred(SpacecraftState s, boolean increasing) Handle an fov event and choose what to do next.
double	g(SpacecraftState s) Compute the value of the switching function.
org.apache.commons.math.geometry.Vector3D	getAxis1() Get the direction of fov 1st dihedral axis.
org.apache.commons.math.geometry.Vector3D	getAxis2() Get the direction of fov 2nd dihedral axis.
org.apache.commons.math.geometry.Vector3D	getCenter() Get the direction of fov center.
double	getHalfAperture1() Get the half aperture angle of fov 1st dihedra.
double	getHalfAperture2() Get the half aperture angle of fov 2nd dihedra.
PVCoordinatesProvider	getPVTarget() Get the position/velocity provider of the target .

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

getMaxCheckInterval, getMaxIterationCount, getThreshold, resetState

Methods inherited from class java.lang.Object

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

Constructor Detail

DihedralFieldOfViewDetector

public DihedralFieldOfViewDetector(double maxCheck,
                                   PVCoordinatesProvider pvTarget,
                                   org.apache.commons.math.geometry.Vector3D center,
                                   org.apache.commons.math.geometry.Vector3D axis1,
                                   double halfAperture1,
                                   org.apache.commons.math.geometry.Vector3D axis2,
                                   double halfAperture2)

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

axis1 - Fov dihedral axis 1

halfAperture1 - Fov dihedral half aperture angle 1

axis2 - Fov dihedral axis 2

halfAperture2 - Fov dihedral half aperture angle 2

Method Detail

getPVTarget

public PVCoordinatesProvider getPVTarget()

Get the position/velocity provider of the target .

Returns:

the position/velocity provider of the target

getCenter

public org.apache.commons.math.geometry.Vector3D getCenter()

Get the direction of fov center.

Returns:

the direction of fov center

getAxis1

public org.apache.commons.math.geometry.Vector3D getAxis1()

Get the direction of fov 1st dihedral axis.

Returns:

the direction of fov 1st dihedral axis

getHalfAperture1

public double getHalfAperture1()

Get the half aperture angle of fov 1st dihedra.

Returns:

the half aperture angle of fov 1st dihedras

getHalfAperture2

public double getHalfAperture2()

Get the half aperture angle of fov 2nd dihedra.

Returns:

the half aperture angle of fov 2nd dihedras

getAxis2

public org.apache.commons.math.geometry.Vector3D getAxis2()

Get the direction of fov 2nd dihedral axis.

Returns:

the direction of fov 2nd dihedral axis

eventOccurred

public int eventOccurred(SpacecraftState s,
                         boolean increasing)
                  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 overriding the eventOccurred method in a derived class.

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)

Returns:

one of EventDetector.STOP, EventDetector.RESET_STATE, EventDetector.RESET_DERIVATIVES or EventDetector.CONTINUE

Throws:

OrekitException - if some specific error occurs

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 target signed distance to the closest fov boundary. 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

Returns:

value of the switching function

Throws:

OrekitException - if some specific error occurs