Orbit Class Reference

Sequence of platform ephemeris samples (state vectors) with uniform temporal spacing, supporting efficient lookup and interpolation. More...

#include <Orbit.h>

Public Member Functions
	Orbit (const std::vector< StateVector > &statevecs, OrbitInterpMethod interp_method=OrbitInterpMethod::Hermite, const std::string &type="")
	Construct from list of state vectors.
	Orbit (const std::vector< StateVector > &statevecs, const std::string &type)
	Construct from list of state vectors and orbit type.
	Orbit (const std::vector< StateVector > &statevecs, const DateTime &reference_epoch, OrbitInterpMethod interp_method=OrbitInterpMethod::Hermite, const std::string &type="")
	Construct from list of state vectors and reference epoch.
Orbit	crop (const DateTime &start, const DateTime &end, int npad=0) const
	Create a new Orbit containing data in the requested interval.
std::vector< StateVector >	getStateVectors () const
	Export list of state vectors.
void	setStateVectors (const std::vector< StateVector > &)
	Set orbit state vectors.
const DateTime &	referenceEpoch () const
	Reference epoch (UTC)
void	referenceEpoch (const DateTime &)
	Set reference epoch (UTC)
OrbitInterpMethod	interpMethod () const
	Interpolation method.
void	interpMethod (OrbitInterpMethod interp_method)
	Set interpolation method.
const std::string &	type () const
	Orbit ephemeris precision type.
void	type (const std::string &orbit_type)
	Set the orbit ephemeris precision type.
double	startTime () const
	Time of first state vector relative to reference epoch (s)
double	midTime () const
	Time of center of orbit relative to reference epoch (s)
double	endTime () const
	Time of last state vector relative to reference epoch (s)
DateTime	startDateTime () const
	UTC time of first state vector.
DateTime	midDateTime () const
	UTC time of center of orbit.
DateTime	endDateTime () const
	UTC time of last state vector.
bool	contains (double time) const
	Check if time falls in the valid interpolation domain.
double	spacing () const
	Time interval between state vectors (s)
int	size () const
	Number of state vectors in orbit.
const Linspace< double > &	time () const
	Get state vector times relative to reference epoch (s)
double	time (int idx) const
	Get the specified state vector time relative to reference epoch (s)
const std::vector< Vec3 > &	position () const
	Get state vector positions in ECEF coordinates (m)
const Vec3 &	position (int idx) const
	Get the specified state vector position in ECEF coordinates (m)
const std::vector< Vec3 > &	velocity () const
	Get state vector velocities in ECEF coordinates (m/s)
const Vec3 &	velocity (int idx) const
	Get the specified state vector velocity in ECEF coordinates (m/s)
isce3::error::ErrorCode	interpolate (Vec3 *position, Vec3 *velocity, double t, OrbitInterpBorderMode border_mode=OrbitInterpBorderMode::Error) const
	Interpolate platform position and/or velocity.

Detailed Description

Sequence of platform ephemeris samples (state vectors) with uniform temporal spacing, supporting efficient lookup and interpolation.

DateTimes are expected to be UTC. Positions & velocities are in meters and meters per second respectively and in ECEF coordinates w.r.t WGS84 ellipsoid.

Platform position and velocity are stored at timepoints relative to a reference epoch. For best accuracy, reference epoch should be within 24 hours of orbit time tags.

Constructor & Destructor Documentation

Orbit() [1/3]

isce3::core::Orbit::Orbit	(	const std::vector< StateVector > &	statevecs,
		OrbitInterpMethod	interp_method = OrbitInterpMethod::Hermite,
		const std::string &	type = "" )

Construct from list of state vectors.

Reference epoch defaults to time of first state vector

Parameters

[in]	statevecs	State vectors
[in]	interp_method	Interpolation method
[in]	type	Orbit ephemeris precision type

Orbit() [2/3]

isce3::core::Orbit::Orbit	(	const std::vector< StateVector > &	statevecs,
		const std::string &	type )

Construct from list of state vectors and orbit type.

Reference epoch defaults to time of first state vector

Parameters

[in]	statevecs	State vectors
[in]	type	Orbit ephemeris precision type

Orbit() [3/3]

isce3::core::Orbit::Orbit	(	const std::vector< StateVector > &	statevecs,
		const DateTime &	reference_epoch,
		OrbitInterpMethod	interp_method = OrbitInterpMethod::Hermite,
		const std::string &	type = "" )

Construct from list of state vectors and reference epoch.

Parameters

[in]	statevecs	State vectors
[in]	reference_epoch	Reference epoch
[in]	interp_method	Interpolation method
[in]	orbit_type	Orbit ephemeris precision type

Member Function Documentation

crop()

Orbit isce3::core::Orbit::crop	(	const DateTime &	start,
		const DateTime &	end,
		int	npad = 0 ) const

Create a new Orbit containing data in the requested interval.

Parameters

[in]	start	Beginning of time interval
[in]	end	End of time interval
[in]	npad	Minimal number of state vectors to include past each of the given time bounds (useful to guarantee adequate support for interpolation).

Returns

Orbit object with data containing start & end times. The reference epoch and interpolation method are preserved.

interpolate()

ErrorCode isce3::core::Orbit::interpolate	(	Vec3 *	position,
		Vec3 *	velocity,
		double	t,
		OrbitInterpBorderMode	border_mode = OrbitInterpBorderMode::Error ) const

Interpolate platform position and/or velocity.

If either position or velocity is a null pointer, that output will not be computed. This may improve runtime by avoiding unnecessary operations.

Parameters

[out]	position	Interpolated position
[out]	velocity	Interpolated velocity
[in]	t	Interpolation time
[in]	border_mode	Mode for handling interpolation outside orbit domain

Returns

Error code indicating exit status

referenceEpoch()

void isce3::core::Orbit::referenceEpoch

(

const DateTime &

reference_epoch

)

Set reference epoch (UTC)

Also updates relative time tags so that referenceEpoch() + TimeDelta(time()[i]) results in the same absolute time tags before and after this call.

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The documentation for this class was generated from the following files:

• /home/runner/work/isce3/isce3/cxx/isce3/core/Orbit.h
• /home/runner/work/isce3/isce3/cxx/isce3/core/Orbit.cpp