Package pygeodesy :: Module azimuthal
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Module azimuthal

Azimuthal projection classes Equidistant, EquidistantKarney, Gnomonic, GnomonicKarney, LambertEqualArea, Orthographic, Stereographic and AzimuthalError and functions equidistant and gnomonic.

EquidistantKarney and GnomonicKarney require Charles Karney's Python geographiclib package to be installed.

Other azimuthal classes implement only (**) Snyder's FORMULAS FOR THE SPHERE and use those for any datum, spherical and ellipsoidal. The radius used for the latter is the ellipsoid's mean radius of curvature at the latitude of the projection center point. For further justification, see the first paragraph under Snyder's FORMULAS FOR THE ELLIPSOID, page 197.

Page numbers in Snyder references apply to John P. Snyder, "Map Projections -- A Working Manual", 1987.

See also here, especially the Comparison of the Azimuthal equidistant projection and some azimuthal projections centred on 90° N at the same scale, ordered by projection altitude in Earth radii.


Version: 20.10.05

Classes
  _AzimuthalBase
(INTERNAL) Base class for azimuthal projections.
  AzimuthalError
An azimuthal Equidistant, EquidistantKarney, Gnomonic, LambertEqualArea, Orthographic, Stereographic or {Azimuthal7Tuple} issue.
  Azimuthal7Tuple
7-Tuple (x, y, lat, lon, azimuth, scale, datum), in meter, meter, degrees90, degrees180, degrees360, float and Datum where (x, y) is the projected, (lat, lon) the geodetic location, azimuth the azimuth direction clockwise from true North and scale is the projection scale, either (1 / reciprocal or 1 or -1 in the Equidistant case).
  Equidistant
Azimuthal equidistant projection for the sphere**, see Snyder, pp 195-197 and MathWorld-Wolfram.
  EquidistantKarney
Azimuthal equidistant projection, a Python version of Karney's C++ class AzimuthalEquidistant, requiring package geographiclib to be installed.
  Gnomonic
Azimuthal gnomonic projection for the sphere**, see Snyder, pp 164-168 and MathWorld-Wolfram.
  GnomonicKarney
Azimuthal gnomonic projection, a Python version of Karney's C++ class Gnomonic, requiring package geographiclib to be installed.
  LambertEqualArea
Lambert-equal-area projection for the sphere**, see Snyder, pp 185-187 and MathWorld-Wolfram.
  Orthographic
Orthographic projection for the sphere**, see Snyder, pp 148-153 and MathWorld-Wolfram.
  Stereographic
Stereographic projection for the sphere**, see Snyder, pp 157-160 and MathWorld-Wolfram.
Functions
 
equidistant(lat0, lon0, datum=Datum(name='WGS84', ellipsoid=Ellipsoids.WGS84, transform=Tran..., name='')
If Karney's geographiclib package is installed, return an EquidistantKarney otherwise an Equidistant instance.
 
gnomonic(lat0, lon0, datum=Datum(name='WGS84', ellipsoid=Ellipsoids.WGS84, transform=Tran..., name='')
If Karney's geographiclib package is installed, return an GnomonicKarney otherwise an Gnomonic instance.
Variables
  __all__ = _ALL_LAZY.azimuthal
Function Details

equidistant (lat0, lon0, datum=Datum(name='WGS84', ellipsoid=Ellipsoids.WGS84, transform=Tran..., name='')

 

If Karney's geographiclib package is installed, return an EquidistantKarney otherwise an Equidistant instance.

Arguments:
  • lat0 - Latitude of center point (degrees90).
  • lon0 - Longitude of center point (degrees180).
  • datum - Optional datum or ellipsoid (Datum, Ellipsoid, Ellipsoid2 or a_f2Tuple) or scalar earth radius (meter).
  • name - Optional name for the projection (str).
Returns:
An EquidistantKarney or Equidistant instance.
Raises:
  • AzimuthalError - Invalid lat0, lon0 or sperical datum.
  • TypeError - Invalid datum.

gnomonic (lat0, lon0, datum=Datum(name='WGS84', ellipsoid=Ellipsoids.WGS84, transform=Tran..., name='')

 

If Karney's geographiclib package is installed, return an GnomonicKarney otherwise an Gnomonic instance.

Arguments:
  • lat0 - Latitude of center point (degrees90).
  • lon0 - Longitude of center point (degrees180).
  • datum - Optional datum or ellipsoid (Datum, Ellipsoid, Ellipsoid2 or a_f2Tuple) or scalar earth radius (meter).
  • name - Optional name for the projection (str).
Returns:
An GnomonicKarney or Gnomonic instance.
Raises:
  • AzimuthalError - Invalid lat0, lon0 or sperical datum.
  • TypeError - Invalid datum.