org.orekit.attitudes
Class GroundPointing

java.lang.Object
  org.orekit.attitudes.GroundPointing

All Implemented Interfaces:

java.io.Serializable, AttitudeLaw

Direct Known Subclasses:

BodyCenterPointing, GroundPointingWrapper, LofOffsetPointing, NadirPointing, TargetPointing

public abstract class GroundPointing
extends java.lang.Object
implements AttitudeLaw

This class handles ground pointing attitude laws.

This class is a basic model for different kind of ground pointing attitude laws, such as : body center pointing, nadir pointing, target pointing, etc...

The object GroundPointing is guaranteed to be immutable.

Version:

$Revision:1665 $ $Date:2008-06-11 12:12:59 +0200 (mer., 11 juin 2008) $

Author:

Véronique Pommier-Maurussane

See Also:

AttitudeLaw, Serialized Form

Constructor Summary

protected

GroundPointing(Frame bodyFrame) Default constructor.

Method Summary

Attitude	getAttitude(Orbit orbit) Compute the attitude corresponding to an orbital state.
Frame	getBodyFrame() Get the body frame.
protected abstract org.apache.commons.math.geometry.Vector3D	getTargetPoint(Orbit orbit, Frame frame) Compute the target point in specified frame.
protected PVCoordinates	getTargetPV(Orbit orbit, Frame frame) Compute the target point position/velocity in specified frame.

Methods inherited from class java.lang.Object

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

Constructor Detail

GroundPointing

protected GroundPointing(Frame bodyFrame)

Default constructor. Build a new instance with arbitrary default elements.

Parameters:

bodyFrame - the frame that rotates with the body

Method Detail

getBodyFrame

public Frame getBodyFrame()

Get the body frame.

Returns:

body frame

getTargetPoint

protected abstract org.apache.commons.math.geometry.Vector3D getTargetPoint(Orbit orbit,
                                                                            Frame frame)
                                                                     throws OrekitException

Compute the target point in specified frame.

Parameters:

orbit - orbit state

frame - frame in which observed ground point should be provided

Returns:

observed ground point position in specified frame

Throws:

OrekitException - if some specific error occurs, such as no target reached

getTargetPV

protected PVCoordinates getTargetPV(Orbit orbit,
                                    Frame frame)
                             throws OrekitException

Compute the target point position/velocity in specified frame.

The default implementation use a simple two points finite differences scheme, it may be replaced by more accurate models in specialized implementations.

Parameters:

orbit - orbit state

frame - frame in which observed ground point should be provided

Returns:

observed ground point position/velocity in specified frame

Throws:

OrekitException - if some specific error occurs, such as no target reached

getAttitude

public Attitude getAttitude(Orbit orbit)
                     throws OrekitException

Compute the attitude corresponding to an orbital state.

Specified by:

getAttitude in interface AttitudeLaw

Parameters:

orbit - orbit state for which attitude is requested

Returns:

attitude attitude on the specified orbit, using orbit inertial frame as its reference frame

Throws:

OrekitException - if attitude cannot be computed