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Unigine::Ellipsoid Class

Warning
The functionality described in this article is not available in the Community SDK edition.
You should upgrade to Engineering / Sim SDK edition to use it.
Header: #include <UnigineEllipsoid.h>

The Ellipsoid class handles the geodetic transformations:

  • Specifies the Ellipsoid settings: semimajor axis, flattening coefficient
  • Performs systems coordinates (ECF, ENU, NED, Geodetic) conversion
  • Solves direct and inverse geodetic problems with different calculation mode (Great Circle and Vincenty algorithms)

This class is used to create an Ellipsoid instance to the GeodeticPivot class.

Here is a code snippet of the Ellipsoid class usage:

Source code (C++)
#include "UnigineMathLib.h"
#include "UnigineGeodetics.h"
#include "UnigineEllipsoid.h"

using namespace Unigine;
using namespace Unigine::Math;

/* ... */

// define the geodetic origin
dvec3 tomsk_origin = dvec3(58.49771, 84.97437, 117.0);

// create a new GeodeticPivot object
GeodeticPivotPtr pivot = GeodeticPivot::create();

// create a new ellipsoid and specify its settings
EllipsoidPtr ellipsoid = pivot->getEllipsoid();
ellipsoid->setSemimajorAxis(80000.0f);
ellipsoid->setMode(Ellipsoid::MODE_FAST);

// set the ellipsoid to the pivot
pivot->setOrigin(tomsk_origin);
pivot->setEllipsoid(ellipsoid);

Ellipsoid Class

Members


static EllipsoidPtr create ( double semimajor_axis, double flattening ) #

Constructor. Creates a new Ellipsoid class instance with given flattening and semimajor axis.

Arguments

  • double semimajor_axis - Semimajor axis.
  • double flattening - Flattening coefficient.

static EllipsoidPtr create ( ) #

Constructor. Creates a new Ellipsoid class instance (WGS84 Ellipsoid).

Math::dvec3 getENUSurfacePoint ( const Math::dvec3 & geodetic_origin, const Math::dvec3 & tangent_point ) #

Returns surface point by using tangent point coordinates.
Notice
The Up-axis (Z+) direction in ENU points upward along the ellipsoid normal, while in UNIGINE implementation of ENU it goes from the Earth's center.

Arguments

  • const Math::dvec3 & geodetic_origin - The origin in ellipsoid coordinates (latitude (degrees), longitude (degrees) and altitude (meters).
  • const Math::dvec3 & tangent_point - Tangent point coordinates to converted (curved) to surface coordinates (offset related to point of junction).

Return value

Surface point coordinates.

Math::dvec3 getENUTangentPoint ( const Math::dvec3 & geodetic_origin, const Math::dvec3 & surface_point ) #

Returns tangent point ENU coordinates based on the geographical coordinates.
Notice
The Up-axis (Z+) direction in ENU points upward along the ellipsoid normal, while in UNIGINE implementation of ENU it goes from the Earth's center.

Arguments

  • const Math::dvec3 & geodetic_origin - The origin in ellipsoid coordinates (latitude (degrees), longitude (degrees) and altitude (meters).
  • const Math::dvec3 & surface_point - Surface point coordinates to be converted (flatten) to tangent point (offset related to point of junction).

Return value

Tangent point coordinates.

Math::quat getENUWorldRotation ( const Math::dvec3 & geodetic_origin ) #

Returns the world rotation quaternion in ENU coordinates.
Notice
The Up-axis (Z+) direction in ENU points upward along the ellipsoid normal, while in UNIGINE implementation of ENU it goes from the Earth's center.

Arguments

  • const Math::dvec3 & geodetic_origin - The origin in ellipsoid coordinates (latitude (degrees), longitude (degrees) and altitude (meters).

Return value

World rotation in ENU coordinates.

Math::dmat4 getENUWorldTransform ( const Math::dvec3 & geodetic_origin ) #

Returns the world transformation matrix in ENU coordinates.
Notice
The Up-axis (Z+) direction in ENU points upward along the ellipsoid normal, while in UNIGINE implementation of ENU it goes from the Earth's center.

Arguments

  • const Math::dvec3 & geodetic_origin - The origin in ellipsoid coordinates (latitude (degrees), longitude (degrees) and altitude (meters).

Return value

World transformation matrix in ENU coordinates.

void setFlattening ( double flattening ) #

Sets new flattening for the ellipsoid.

Arguments

  • double flattening - Flattening coefficient of the ellipsoid. If the value is 0, the ellipsoid has a sphere shape, for 1 the ellipsoid has a circle (completely flat) shape.

double getFlattening ( ) #

Returns flattening coefficient of the ellipsoid.

Return value

Flattening coefficient of the ellipsoid.

double getMeanRadius ( ) #

Returns the mean radius of the ellipsoid.

Return value

The mean radius of the ellipsoid.

int isSupported ( ) #

Returns a value indicating if the geodetics feature is enabled.

Return value

1 if the geodetics feature is enabled; otherwise, 0.

void setMode ( int mode ) #

Sets the calculation mode.

Arguments

int getMode ( ) #

Returns the calculation mode int value: 1 if the mode is MODE_ACCURATE, 0 if the mode is MODE_FAST.

Return value

1 if the mode is MODE_ACCURATE, 0 if the mode is MODE_FAST.

Math::dvec3 getNEDSurfacePoint ( const Math::dvec3 & geodetic_origin, const Math::dvec3 & tangent_point ) #

Returns surface point by using tangent point coordinates.
Notice
The Down-axis direction in NED points downward along the ellipsoid normal, while in UNIGINE implementation of NED it goes through the Earth's center.

Arguments

  • const Math::dvec3 & geodetic_origin - The origin in ellipsoid coordinates (latitude (degrees), longitude (degrees) and altitude (meters).
  • const Math::dvec3 & tangent_point - Tangent point coordinates to converted (curved) to surface coordinates (offset related to point of junction).

Return value

Surface point coordinates.

Math::dvec3 getNEDTangentPoint ( const Math::dvec3 & geodetic_origin, const Math::dvec3 & surface_point ) #

Returns tangent point NED coordinates based on the geographical coordinates.
Notice
The Down-axis direction in NED points downward along the ellipsoid normal, while in UNIGINE implementation of NED it goes through the Earth's center.

Arguments

  • const Math::dvec3 & geodetic_origin - The origin in ellipsoid coordinates (latitude (degrees), longitude (degrees) and altitude (meters).
  • const Math::dvec3 & surface_point - Surface point coordinates to be converted (flatten) to tangent point (offset related to point of junction).

Return value

Tangent point coordinates.

Math::quat getNEDWorldRotation ( const Math::dvec3 & geodetic_origin ) #

Returns the world rotation quaternion in NED coordinates.
Notice
The Down-axis direction in NED points downward along the ellipsoid normal, while in UNIGINE implementation of NED it goes through the Earth's center.

Arguments

  • const Math::dvec3 & geodetic_origin - The origin in ellipsoid coordinates (latitude (degrees), longitude (degrees) and altitude (meters).

Return value

World rotation in NED coordinates.

Math::dmat4 getNEDWorldTransform ( const Math::dvec3 & geodetic_origin ) #

Returns the world transformation matrix in NED coordinates.
Notice
The Down-axis direction in NED points downward along the ellipsoid normal, while in UNIGINE implementation of NED it goes through the Earth's center.

Arguments

  • const Math::dvec3 & geodetic_origin - The origin in ellipsoid coordinates (latitude (degrees), longitude (degrees) and altitude (meters).

Return value

World transformation matrix in NED coordinates.

void setSemimajorAxis ( double axis ) #

Sets new semimajor axis of the ellipsoid.

Arguments

  • double axis - Semimajor axis length in units.

double getSemimajorAxis ( ) #

Returns semimajor axis length of the ellipsoid in units.

Return value

Semimajor axis of the ellipsoid.

double getSemimajorEccentricitySqr ( ) #

Returns the squared eccentricity calculated along the semimajor axis.

Return value

Squared eccentricity calculated along the semimajor axis.

double getSemiminorAxis ( ) #

Returns semiminor axis of the ellipsoid in units.

Return value

Semiminor axis of the ellipsoid in units.

double getSemiminorEccentricitySqr ( ) #

Returns the squared eccentricity calculated along the semiminor axis.

Return value

Squared eccentricity calculated along the semiminor axis.

Math::dvec3 solveGeodeticDirect ( const Math::dvec3 & geodetic_start, double bearing, double distance ) #

Solves the direct geodetic problem: calculates end point coordinates on the ellipsoid by using given start point, distance between points, and bearing value.

Arguments

  • const Math::dvec3 & geodetic_start - Start point on the ellipsoid.
  • double bearing - Bearing value.
  • double distance - Distance between two points on the ellipsoid.

void solveGeodeticInverse ( const Math::dvec3 & geodetic_start, const Math::dvec3 & geodetic_end, double & bearing, double & distance ) #

Solves the inverse geodetic problem: calculates distance and bearing values by using given start and end points on the ellipsoid.

Arguments

  • const Math::dvec3 & geodetic_start - Start point on the ellipsoid.
  • const Math::dvec3 & geodetic_end - End point on the ellipsoid.
  • double & bearing - Variable to save the calculated bearing value.
  • double & distance - Variable to save the calculated distance value.

Math::dvec3 toECF ( const Math::dvec3 & geodetic_coords ) #

Converts geodetic coordinates to Cartesian (ECF).

Arguments

  • const Math::dvec3 & geodetic_coords - Ellipsoid coordinates (latitude (degrees), longitude (degrees) and altitude (meters)) to be converted to Cartesian.

Return value

Cartesian coordinates.

Math::dvec3 toENU ( const Math::dvec3 & geodetic_origin, const Math::dvec3 & geodetic_coords ) #

Converts geodetic coordinates to ENU (East, North, Up).
Notice
The Up-axis (Z+) direction in ENU points upward along the ellipsoid normal, while in UNIGINE implementation of ENU it goes from the Earth's center.

Arguments

  • const Math::dvec3 & geodetic_origin - The origin in ellipsoid coordinates (latitude (degrees), longitude (degrees) and altitude (meters).
  • const Math::dvec3 & geodetic_coords - Coordinates to be converted to ENU.

Return value

ENU coordinates.

Math::dvec3 toGeodetic ( const Math::dvec3 & ecf_coords, int need_alt = 1 ) #

Converts Cartesian (ECF) coordinates to Ellipsoid.

Arguments

  • const Math::dvec3 & ecf_coords - Cartesian ECF coordinates to be converted.
  • int need_alt - Flag indicating if altitude is to be calculated. 1 to calculate altitude, 0 - to skip altitude calculation.The default value is 1.

Return value

Ellipsoid coordinates (latitude (degrees), longitude (degrees) and altitude (meters)

Math::dvec3 toNED ( const Math::dvec3 & geodetic_origin, const Math::dvec3 & geodetic_coords ) #

Converts geodetics coordinates to NED (North, East, Down).
Notice
The Down-axis direction in NED points downward along the ellipsoid normal, while in UNIGINE implementation of NED it goes through the Earth's center.

Arguments

  • const Math::dvec3 & geodetic_origin - The origin in ellipsoid coordinates (latitude (degrees), longitude (degrees) and altitude (meters).
  • const Math::dvec3 & geodetic_coords - Coordinates to be converted to NED.

Return value

NED coordinates.
Last update: 2021-04-01
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