Geodetic

Geodetic#

Specialized Instances#

class sasktran2.WGS84[source]#

Bases: Geodetic

A geodetic object based upon the standard WGS84 ellipsoid. See sasktran2.Geodetic for more information and usage.

class sasktran2.SphericalGeoid(radius: float)[source]#

Bases: Geodetic

A geoid that is represented as a perfect sphere. See sasktran2.Geodetic for more information and usage.

Parameters:

radius (float) – Radius of the sphere in [m]

sk.Geodetic#

class sasktran2.Geodetic(self: sasktran2._core.Geodetic, equatorial_radius: float, flattening_factor: float)#

Bases: pybind11_object

A geodetic object based on a given equatorial (semi-major) radius and flattening factor.

Standard usage is to create a geodetic object, and then initialize it through one of the from_* methods.

Parameters:

  • equatorial_radius (float) – Radius at the equator (semi-major) of the ellipsoid.

  • flattening_factor (float) – Flattening factor of the ellipsoid. This is defined as (a-b)/a, where a is the semi-major axis and b is the semi-minor radius

property altitude#

Altitude in [m] above the surface of the ellipsoid.

altitude_intercepts(self: sasktran2._core.Geodetic, altitude: float, observer: numpy.ndarray[numpy.float64[3, 1]], look_vector: numpy.ndarray[numpy.float64[3, 1]]) → tuple[numpy.ndarray[numpy.float64[3, 1]], numpy.ndarray[numpy.float64[3, 1]]]#

Calculate the two intersections of a line of sight and an altitude.

Parameters:

  • altitude (float) – Altitude in meters.

  • observer (np.ndarray) – Three element array containing the obsever position in geocentric coordinates.

  • look_vector (np.ndarray) – Three element array containing a normalized look vector.

Returns:

  • np.ndarray – Three element array containing the first (entering) intercept in geocentric coordinates.

  • np.ndarray – Three element array containing the second (exiting) intercept in geocentric coordinates.

Examples

>>> import sasktran2 as sk
>>> import numpy as np
>>> geodetic = sk.WGS84()
>>> look = geodetic.from_tangent_altitude(15322, [3.676013154788849600e+005, 1.009976313640051500e+006, \
                                            -6.871601202127538600e+006], [0, 0, 1])
>>> obs = geodetic.location
>>> intercept1, intercept2 = geodetic.altitude_intercepts(16000, obs, look)
>>> print(np.array_str(intercept1, precision=3))
[ 1147302.059  3152186.5   -5425360.027]
>>> print(np.array_str(intercept2, precision=3))
[ 1201098.489  3299990.978 -5325574.803]
from_lat_lon_alt(self: sasktran2._core.Geodetic, latitude: float, longitude: float, altitude: float) → None#

Initializes the Geodetic based on a specifiec latitude, longitude, and altitude.

Parameters:

  • latitude (float) – Latitude in degrees (-90 to 90)

  • longitude (float) – Longitude in degrees (0 to 360 or -180 to 180)

  • altitude (float) – Altitude above the geoid in metres

Examples

>>> import sasktran2 as sk
>>> geodetic = sk.WGS84()
>>> geodetic.from_lat_lon_alt(latitude=-15, longitude=-20, altitude=7342)
>>> print(geodetic)
WGS84 Location:
Latitude: -15.0, Longitude: 340.0, Altitude: 7342.0
from_tangent_altitude(self: sasktran2._core.Geodetic, altitude: float, observer: numpy.ndarray[numpy.float64[3, 1]], boresight: numpy.ndarray[numpy.float64[3, 1]]) → numpy.ndarray[numpy.float64[3, 1]]#

Initialized the Geodetic from a specified tangent altitude, obsever location, and bore sight plane.

Parameters:

  • altitude (float) – Tangent altitude in meters

  • observer (np.ndarray) – Three element array containing the obsever position in geocentric coordinates

  • boresight (np.ndarray) – Three element array containing a normalized look vector that is within the bore sight plane.

Returns:

Three element array containing the normalized look vector to the tangent point.

Return type:

np.ndarray

Examples

>>> import sasktran2 as sk
>>> geodetic = sk.WGS84()
>>> look = geodetic.from_tangent_altitude(15322, [ 3.676013154788849600e+005, 1.009976313640051500e+006,\
                                                  -6.871601202127538600e+006], [0, 0, 1])
>>> print(look)
[0.28880556 0.79348676 0.53569591]
>>> print(geodetic)
WGS84 Location:
Latitude: -57.60888188776806, Longitude: 70.00000000000001, Altitude: 15321.971935882739
from_tangent_point(self: sasktran2._core.Geodetic, observer: numpy.ndarray[numpy.float64[3, 1]], look_vector: numpy.ndarray[numpy.float64[3, 1]]) → None#

Initializes the Geodetic by calculating the tangent point from an observer position and look vector

Parameters:

  • observer (np.ndarray) – Three element array containing the observer position in geocentric coordinates

  • look_vector (np.ndarray) – Three element array containing a normalized look vector

Examples

>>> import sasktran2 as sk
>>> geodetic = sk.WGS84()
>>> geodetic.from_tangent_point([ 3.676013154788849600e+005, 1.009976313640051500e+006,\
                                 -6.871601202127538600e+006], [ 2.884568631765662100e-001,\
                                  7.925287180643269000e-001,  5.372996083468238900e-001])
>>> print(geodetic)
WGS84 Location:
Latitude: -57.500000192733594, Longitude: 70.0, Altitude: 10002.99586173162
from_xyz(self: sasktran2._core.Geodetic, location: numpy.ndarray[numpy.float64[3, 1]]) → None#

Initializes the Geodetic from a geocentric location

Parameters:

location (np.ndarray) – Three element vector containing a location in geocentric coordinates

Examples

>>> import sasktran2 as sk
>>> geodetic = sk.WGS84()
>>> geodetic.from_xyz([ 5797230.47518212, -2110019.3341472, -1642001.16317228])
>>> print(geodetic)
WGS84 Location:
Latitude: -14.999999973747736, Longitude: 340.00000000000006, Altitude: 7344.999610390202
property latitude#

Geodetic latitude in degrees

property local_south#

A unit vector pointing in the local south direction

property local_up#

A unit vector pointing up (perpindicular to the ellipsoidal surface)

property local_west#

A unit vector pointing in the local west direction

property location#

Geocentric location in cartesian coordinates

property longitude#

Geodetic longitude in degrees

property valid#

True if the geodetic object has been initialized, False otherwise.

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