Package pygeodesy :: Module azimuthal |
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# Module azimuthal

Azimuthal projection classes Equidistant, EquidistantKarney, Gnomonic, GnomonicKarney, LambertEqualArea, Orthographic and Stereographic, classes AzimuthalError, Azimuthal7Tuple 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: 21.02.18

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`, `scalar` and `Datum` where `(x, y)` is the projected easting and northing of point, `(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** (aka Lambert zenithal equal-area projection, 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 a 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 (spherical) `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 a 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: A GnomonicKarney or Gnomonic instance. Raises: `AzimuthalError` - Invalid `lat0`, `lon0` or (spherical) `datum`. `TypeError` - Invalid `datum`.