Table of Contents

Class GeodeticLibrary

Namespace
NominalSystems.Universe
Assembly
NominalSystems.Universe.dll

[Nominal] This is a static library for geodetic functions that are used to calculate the position of a point on the Earth's or other celestial body's surface.

public static class GeodeticLibrary
Inheritance
GeodeticLibrary

Methods

GeodeticToVectorElements(GeodeticElements, Matrix3, double, double)

Converts from a Lat/Long/Altitude coordinates to planet-centered, planet-fixed coordinates given a planet radius. This assumes that the object is located at the peak of the orbit equal to the lat and lon of the object. This also assumes a circular orbit.

public static VectorElements GeodeticToVectorElements(GeodeticElements llaPosition, Matrix3 j2000, double planetRadius, double mu)

Parameters

llaPosition GeodeticElements

[-] Position in latitude/longitude/altitude coordinates

j2000 Matrix3

[-] Planet rotation matrix

planetRadius double

[m] Planetary radius, assumed to be constant (i.e., spherical)

mu double

[kg m^2 s^3] The gravitational constant for the body orbiting

Returns

VectorElements

[m]/[m/s] Final position and velocity in the planet-centered, planet-fixed frame.

GetGeodeticDistance(double, GeodeticElements, GeodeticElements)

Determines the Distance between two Geodetic elements on a surface of a planet. This assumes both geodetic elements are on the same planet.

public static double GetGeodeticDistance(double planetRadius, GeodeticElements LLA1, GeodeticElements LLA2)

Parameters

planetRadius double

[m] The radius of the planet

LLA1 GeodeticElements

The first Geodetic element

LLA2 GeodeticElements

The second Geodetic element

Returns

double

[m] The calculated distance between the two elements

GetRotationVelocity(GeodeticElements, Matrix3, Matrix3, double)

Returns the rotation velocity of a particular location on a body based on the geodetic coordinates and the rotation speed of the body at the current point in time. This assumes a PCI frame velocity.

public static Vector3 GetRotationVelocity(GeodeticElements llaPosition, Matrix3 j2000, Matrix3 j2000Dot, double planetRadius)

Parameters

llaPosition GeodeticElements

[deg] The geodetic coordinates to get the rotation at

j2000 Matrix3

[-] The J2000 rotation frame of the body at the current time

j2000Dot Matrix3

[-] The J2000 rotation velocity of the body at the current time

planetRadius double

[m] The radius of the body that the location exists on

Returns

Vector3

[m/s] A PCI frame velocity at the current location

GetWGSRadius(double)

Calculates the radius of the Earth at a given latitude using the World Geodetic System (WGS) 84 standard. This will take in some latitude and will calculate the true radius at that given point on the non-spherical Earth model. This model is independent to any longitude value.

public static double GetWGSRadius(double latitude)

Parameters

latitude double

[m] The latitude of the point to calculate

Returns

double

[m] The radius at the provided latitude.

HCSToPCPF(Matrix3, double, double, double)

Converts a HCS (horizontal coordinate system) rotation frame to a PCPF (planet centered planet fixed) rotation frame with a rotation about the azimuth angle (clockwise from the primary direction) and elevation angles in degrees into a new rotation frame.

public static Matrix3 HCSToPCPF(Matrix3 hcs, double yaw, double pitch, double roll = 0)

Parameters

hcs Matrix3

[-] The HCS frame at the current position

yaw double

[deg] The angle to rotate clockwise about the HCS direction

pitch double

[deg] The angle to rotate about the horizon plane

roll double

[deg] The angle to roll about the final axis

Returns

Matrix3

[-] A rotated HCS rotation in the PCPF frame

LLAToENU(double, double)

Converts a latitude and longitude position to an ENU (east north up) rotation frame.

public static Matrix3 LLAToENU(double latitude, double longitude)

Parameters

latitude double

[deg] The latitude of the position

longitude double

[deg] The longitude of the position

Returns

Matrix3

The ENU rotation frame

LLAToNED(double, double)

Converts a latitude and longitude position to an NED (north east down) rotation frame.

public static Matrix3 LLAToNED(double latitude, double longitude)

Parameters

latitude double

[deg] The latitude of the position

longitude double

[deg] The longitude of the position

Returns

Matrix3

The NED rotation frame

LLAToPCI(GeodeticElements, Matrix3, double)

Converts from a planet-centered inertial coordinates to latitude/longitude/altitude (LLA) coordinates given a planet radius and rotation matrix.

public static Vector3 LLAToPCI(GeodeticElements llaPosition, Matrix3 j2000, double planetRadius)

Parameters

llaPosition GeodeticElements

[-] Position in latitude/longitude/altitude coordinates

j2000 Matrix3

[-] Rotation matrix between inertial and PCPF frames

planetRadius double

[m] Planetary radius, assumed to be constant (i.e., spherical)

Returns

Vector3

[m] Position in inertial coordinates.

LLAToPCPF(GeodeticElements, double)

Converts from a Lat/Long/Altitude coordinates to planet-centered, planet-fixed coordinates given a planet radius.

public static Vector3 LLAToPCPF(GeodeticElements llaPosition, double planetRadius)

Parameters

llaPosition GeodeticElements

[-] Position in latitude/longitude/altitude coordinates

planetRadius double

[m] Planetary radius, assumed to be constant (i.e., spherical)

Returns

Vector3

[m] Final position in the planet-centered, planet-fixed frame.

LLAToSEZ(double, double)

Converts a latitude and longitude position to an SEZ (south east zenith) rotation frame.

public static Matrix3 LLAToSEZ(double latitude, double longitude)

Parameters

latitude double

[deg] The latitude of the position

longitude double

[deg] The longitude of the position

Returns

Matrix3

The SEZ rotation frame

LLAToWGS(GeodeticElements)

Converts a latitude longitude altitude (LLA) to a WGS-84 (Earth centered Earth fixed) terrestrial reference system.

public static GeodeticElements LLAToWGS(GeodeticElements lla)

Parameters

lla GeodeticElements

The LLA position assuming a perfect sphere

Returns

GeodeticElements

The WGS position using the WGS-84 model

PCIToLLA(Vector3, Matrix3, double)

Converts from a planet-centered inertial coordinates to latitude/longitude/altitude (LLA) coordinates given a planet radius and rotation matrix.

public static GeodeticElements PCIToLLA(Vector3 pciPosition, Matrix3 j2000, double planetRadius)

Parameters

pciPosition Vector3

[m] Position vector in PCI coordinates

j2000 Matrix3

[-] 3x3 rotation matrix representing the rotation between PCPF and PCI frames

planetRadius double

[m] Planetary radius, assumed to be constant (i.e., spherical)

Returns

GeodeticElements

Final position in latitude/longitude/altitude coordinates [0] : [deg] latitude above planetary equator [1] : [deg] longitude across planetary meridian [2] : [m] altitude above planet radius

PCIToPCPF(Vector3, Matrix3)

Converts from a planet-centered inertial position (i.e., J2000 ECI) to a planet-centered, planet-fixed position given a rotation matrix.

public static Vector3 PCIToPCPF(Vector3 pciPosition, Matrix3 j2000)

Parameters

pciPosition Vector3

[m] Position vector in PCI coordinates

j2000 Matrix3

[-] 3x3 rotation matrix representing the rotation between PCPF and PCI frames

Returns

Vector3

[m] Position vector in PCPF coordinates

PCPFToLLA(Vector3, double)

Converts from a planet-centered, planet-fixed coordinates to latitude/longitude/altitude (LLA) coordinates given a planet radius.

public static GeodeticElements PCPFToLLA(Vector3 PCPFPosition, double planetRadius)

Parameters

PCPFPosition Vector3

[m] Position vector in PCPF coordinates

planetRadius double

[m] Planetary radius, assumed to be constant (i.e., spherical)

Returns

GeodeticElements

Final position in latitude/longitude/altitude coordinates [0] : [rad] latitude above planetary equator [1] : [rad] longitude across planetary meridian [2] : [m] altitude above planet radius

PCPFToPCI(Vector3, Matrix3)

Converts from a planet-centered, planet-fixed to a planet-centered inertial position (i.e., J2000 ECI) position given a rotation matrix.

public static Vector3 PCPFToPCI(Vector3 PCPFPosition, Matrix3 j2000)

Parameters

PCPFPosition Vector3

[m] Position vector in planet centered, planet fixed coordinates

j2000 Matrix3

[-] Rotation between inertial and PCPF coordinates.

Returns

Vector3

[m] Final position in the planet-centered inertial frame.

PCPFToPCIDCM(Matrix3, Matrix3)

Converts a PCPF (planet-centered planet-fixed) rotation matrix to a PCI (planet-centered inertial) frame, with the combination of the planet rotation matrix and the raw DCM (direction cosine matrix) rotation matrix.

public static Matrix3 PCPFToPCIDCM(Matrix3 PCPF, Matrix3 j2000)

Parameters

PCPF Matrix3

[-] The PCPF DCM rotation matrix

j2000 Matrix3

[-] The SPICE J2000 rotation frame

Returns

Matrix3

[-] The PCI DCM rotation matrix

WGSToLLA(GeodeticElements)

Converts a standard WGS-84 (Earth Centered, Earth Fixed) terrestrial reference system for Earth to an appropriate latitude longitude altitude (LLA) value, assuming the Earth is a perfect sphere.

public static GeodeticElements WGSToLLA(GeodeticElements wgs)

Parameters

wgs GeodeticElements

The WGS position using the WGS-84 model

Returns

GeodeticElements

The LLA position assuming a perfect sphere