Package org.orekit.forces.gravity.potential

Class LazyLoadedGravityFields

java.lang.Object

org.orekit.forces.gravity.potential.LazyLoadedGravityFields

All Implemented Interfaces:

GravityFields

public class LazyLoadedGravityFields
extends Object
implements GravityFields

Loads gravity fields when first requested and can be configured until then. Designed to match the behavior of GravityFieldFactory in Orekit 10.0.

Since:

10.1

Author:

Evan Ward, Fabien Maussion, Pascal Parraud, Luc Maisonobe

See Also:

• GravityFieldFactory

Constructor Summary

Constructors

Constructor	Description
LazyLoadedGravityFields(DataProvidersManager dataProvidersManager, TimeScale timeScale)	Create a factory for gravity fields that uses the given data manager to load the gravity field files.

Method Summary

Modifier and Type	Method	Description
void	addDefaultOceanTidesReaders()	Add the default readers for ocean tides.
void	addDefaultPotentialCoefficientsReaders()	Add the default readers for gravity fields.
void	addOceanTidesReader(OceanTidesReader reader)	Add a reader for ocean tides.
void	addPotentialCoefficientsReader(PotentialCoefficientsReader reader)	Add a reader for gravity fields.
void	clearOceanTidesReaders()	Clear ocean tides readers.
void	clearPotentialCoefficientsReaders()	Clear gravity field readers.
void	configureOceanLoadDeformationCoefficients(OceanLoadDeformationCoefficients oldc)	Configure ocean load deformation coefficients.
NormalizedSphericalHarmonicsProvider	getConstantNormalizedProvider(int degree, int order, AbsoluteDate freezingDate)	Get a constant gravity field normalized coefficients provider frozen at a given epoch.
UnnormalizedSphericalHarmonicsProvider	getConstantUnnormalizedProvider(int degree, int order, AbsoluteDate freezingDate)	Get a constant gravity field unnormalized coefficients provider frozen at a given epoch.
NormalizedSphericalHarmonicsProvider	getNormalizedProvider(int degree, int order)	Get a gravity field normalized coefficients provider.
OceanLoadDeformationCoefficients	getOceanLoadDeformationCoefficients()	Get the configured ocean load deformation coefficients.
List<OceanTidesWave>	getOceanTidesWaves(int degree, int order)	Get the ocean tides waves.
UnnormalizedSphericalHarmonicsProvider	getUnnormalizedProvider(int degree, int order)	Get a gravity field unnormalized coefficients provider.
PotentialCoefficientsReader	readGravityField(int maxParseDegree, int maxParseOrder)	Read a gravity field coefficients provider from the first supported file.

Methods inherited from class java.lang.Object

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

Constructor Details

LazyLoadedGravityFields

public LazyLoadedGravityFields(DataProvidersManager dataProvidersManager,
 TimeScale timeScale)

Create a factory for gravity fields that uses the given data manager to load the gravity field files.

Parameters:

dataProvidersManager - provides access to auxiliary data files.

timeScale - use to parse dates for the addDefaultPotentialCoefficientsReaders(). In Orekit 10.0 it is TT.

Method Details

addPotentialCoefficientsReader

public void addPotentialCoefficientsReader(PotentialCoefficientsReader reader)

Add a reader for gravity fields.

Parameters:

reader - custom reader to add for the gravity field

See Also:

• addDefaultPotentialCoefficientsReaders()
• clearPotentialCoefficientsReaders()

addDefaultPotentialCoefficientsReaders

public void addDefaultPotentialCoefficientsReaders()

Add the default readers for gravity fields.

The default readers support ICGEM, SHM, EGM, GRGS and SHA formats with the default names GravityFieldFactory.ICGEM_FILENAME, GravityFieldFactory.SHM_FILENAME, GravityFieldFactory.EGM_FILENAME, GravityFieldFactory.GRGS_FILENAME, GravityFieldFactory.SHA_FILENAME and don't allow missing coefficients.

See Also:

• addPotentialCoefficientsReader(PotentialCoefficientsReader)
• clearPotentialCoefficientsReaders()

clearPotentialCoefficientsReaders

public void clearPotentialCoefficientsReaders()

Clear gravity field readers.

See Also:

• addPotentialCoefficientsReader(PotentialCoefficientsReader)
• addDefaultPotentialCoefficientsReaders()

addOceanTidesReader

public void addOceanTidesReader(OceanTidesReader reader)

Add a reader for ocean tides.

Parameters:

reader - custom reader to add for the gravity field

See Also:

• addDefaultPotentialCoefficientsReaders()
• clearPotentialCoefficientsReaders()

configureOceanLoadDeformationCoefficients

public void configureOceanLoadDeformationCoefficients(OceanLoadDeformationCoefficients oldc)

Configure ocean load deformation coefficients.

Parameters:

oldc - ocean load deformation coefficients

See Also:

• getOceanLoadDeformationCoefficients()

getOceanLoadDeformationCoefficients

public OceanLoadDeformationCoefficients getOceanLoadDeformationCoefficients()

Get the configured ocean load deformation coefficients.

If configureOceanLoadDeformationCoefficients has never been called, the default value will be the IERS 2010 coefficients.

Returns:

ocean load deformation coefficients

See Also:

• configureOceanLoadDeformationCoefficients(OceanLoadDeformationCoefficients)

addDefaultOceanTidesReaders

public void addDefaultOceanTidesReaders()

Add the default readers for ocean tides.

The default readers support files similar to the fes2004_Cnm-Snm.dat and fes2004.dat as published by IERS, using the configured ocean load deformation coefficients, which by default are the IERS 2010 coefficients, which are limited to degree 6. If higher degree coefficients are needed, the configureOceanLoadDeformationCoefficients method can be called prior to loading the ocean tides model with the high degree coefficients computed by Pascal Gégout.

WARNING: the files referenced in the published conventions have some errors. These errors have been corrected and the updated files can be found here: http://tai.bipm.org/iers/convupdt/convupdt_c6.html.

See Also:

• addPotentialCoefficientsReader(PotentialCoefficientsReader)
• clearPotentialCoefficientsReaders()
• configureOceanLoadDeformationCoefficients(OceanLoadDeformationCoefficients)
• getOceanLoadDeformationCoefficients()

clearOceanTidesReaders

public void clearOceanTidesReaders()

Clear ocean tides readers.

See Also:

• addPotentialCoefficientsReader(PotentialCoefficientsReader)
• addDefaultPotentialCoefficientsReaders()

readGravityField

public PotentialCoefficientsReader readGravityField(int maxParseDegree,
 int maxParseOrder)

Read a gravity field coefficients provider from the first supported file.

If no PotentialCoefficientsReader has been added by calling addPotentialCoefficientsReader or if clearPotentialCoefficientsReaders has been called afterwards, the addDefaultPotentialCoefficientsReaders method will be called automatically.

Parameters:

maxParseDegree - maximal degree to parse

maxParseOrder - maximal order to parse

Returns:

a reader containing already loaded data

Since:

6.0

getConstantNormalizedProvider

public NormalizedSphericalHarmonicsProvider getConstantNormalizedProvider(int degree,
 int order,
 AbsoluteDate freezingDate)

Get a constant gravity field normalized coefficients provider frozen at a given epoch.

If no PotentialCoefficientsReader has been added by calling addPotentialCoefficientsReader or if clearPotentialCoefficientsReaders has been called afterwards, the addDefaultPotentialCoefficientsReaders method will be called automatically.

Specified by:

getConstantNormalizedProvider in interface GravityFields

Parameters:

degree - maximal degree

order - maximal order

freezingDate - freezing epoch

Returns:

a gravity field coefficients provider containing already loaded data

See Also:

• GravityFields.getNormalizedProvider(int, int)

getNormalizedProvider

public NormalizedSphericalHarmonicsProvider getNormalizedProvider(int degree,
 int order)

Get a gravity field normalized coefficients provider.

If no PotentialCoefficientsReader has been added by calling addPotentialCoefficientsReader or if clearPotentialCoefficientsReaders has been called afterwards, the addDefaultPotentialCoefficientsReaders method will be called automatically.

Specified by:

getNormalizedProvider in interface GravityFields

Parameters:

degree - maximal degree

order - maximal order

Returns:

a gravity field coefficients provider containing already loaded data

See Also:

• GravityFields.getConstantNormalizedProvider(int, int, AbsoluteDate)

getConstantUnnormalizedProvider

public UnnormalizedSphericalHarmonicsProvider getConstantUnnormalizedProvider(int degree,
 int order,
 AbsoluteDate freezingDate)

Get a constant gravity field unnormalized coefficients provider frozen at a given epoch.

If no PotentialCoefficientsReader has been added by calling addPotentialCoefficientsReader or if clearPotentialCoefficientsReaders has been called afterwards, the addDefaultPotentialCoefficientsReaders method will be called automatically.

Specified by:

getConstantUnnormalizedProvider in interface GravityFields

Parameters:

degree - maximal degree

order - maximal order

freezingDate - freezing epoch

Returns:

a gravity field coefficients provider containing already loaded data

See Also:

• GravityFields.getUnnormalizedProvider(int, int)

getUnnormalizedProvider

public UnnormalizedSphericalHarmonicsProvider getUnnormalizedProvider(int degree,
 int order)

Get a gravity field unnormalized coefficients provider.

If no PotentialCoefficientsReader has been added by calling addPotentialCoefficientsReader or if clearPotentialCoefficientsReaders has been called afterwards, the addDefaultPotentialCoefficientsReaders method will be called automatically.

Specified by:

getUnnormalizedProvider in interface GravityFields

Parameters:

degree - maximal degree

order - maximal order

Returns:

a gravity field coefficients provider containing already loaded data

See Also:

• GravityFields.getConstantUnnormalizedProvider(int, int, AbsoluteDate)

getOceanTidesWaves

public List<OceanTidesWave> getOceanTidesWaves(int degree,
 int order)

Get the ocean tides waves.

WARNING: as of 2013-11-17, there seem to be an inconsistency when loading one or the other file, for wave Sa (Doodson number 56.554) and P1 (Doodson number 163.555). The sign of the coefficients are different. We think the problem lies in the input files from IERS and not in the conversion (which works for all other waves), but cannot be sure. For this reason, ocean tides are still considered experimental at this date.

If no OceanTidesReader has been added by calling addOceanTidesReader or if clearOceanTidesReaders has been called afterwards, the addDefaultOceanTidesReaders method will be called automatically.

Specified by:

getOceanTidesWaves in interface GravityFields

Parameters:

degree - maximal degree

order - maximal order

Returns:

list of tides waves containing already loaded data