Package pygeodesy :: Module datum
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Module datum

DEPRECATED, use module datums or ellipsoids instead.


Version: 20.08.25

Classes
  Curvature2Tuple
2-Tuple (meridional, prime_vertical) of radii of curvature, both in meter.
  Datum
Ellipsoid and transform parameters for an earth model.
  Ellipsoid
Ellipsoid with equatorial and polar radius, flattening, inverse flattening and other, often used, cached attributes, supporting spherical and oblate and prolate ellipsoidal models.
  Ellipsoid2
Like Ellipsoid, but specified by equatorial radius and flattening.
  Transform
Helmert transformation.
  a_f2Tuple
2-Tuple (a, f) specifying an ellipsoid by equatorial radius (meter) and scalar flattening.
Functions
 
a_b2f(a, b)
Return f, the flattening for a given equatorial and polar radius.
 
a_b2f_(a, b)
Return f_, the inverse flattening for a given equatorial and polar radius.
 
a_f2b(a, f)
Return b, the polar radius for a given equatorial radius and flattening.
 
a_f_2b(a, f_)
Return b, the polar radius for a given equatorial radius and inverse flattening.
 
b_f2a(b, f)
Return a, the equatorial radius for a given polar radius and flattening.
 
b_f_2a(b, f_)
Return a, the equatorial radius for a given polar radius and inverse flattening.
 
f2e2(f)
Return e2, the eccentricity squared for a given flattening.
 
f2e22(f)
Return e22, the 2nd eccentricity squared for a given flattening.
 
f2e32(f)
Return e32, the 3rd eccentricity squared for a given flattening.
 
f2f2(f)
Return f2, the 2nd flattening for a given flattening.
 
f2f_(f)
Return f_, the inverse flattening for a given flattening.
 
f2n(f)
Return n, the 3rd flattening for a given flattening.
 
f_2f(f_)
Return f, the flattening for a given inverse flattening.
 
n2e2(n)
Return e2, the eccentricity squared for a given 3rd flattening.
 
n2f(n)
Return f, the flattening for a given 3rd flattening.
Variables
  Datums = Datums.BD72: Datum(name='BD72', ellipsoid=Ellipsoids....
  Ellipsoids = Ellipsoids.Airy1830: Ellipsoid(name='Airy1830', a...
  R_FM = 6371000.0
  R_KM = 6371.008771415
  R_M = 6371008.771415
  R_MA = 6378137.0
  R_MB = 6356752.0
  R_NM = 3440.06953446921
  R_SM = 3958.753395372691
  R_VM = 6366707.0194937
  Transforms = Transforms.BD72: Transform(name='BD72', tx=106.86...
Function Details

a_b2f (a, b)

 

Return f, the flattening for a given equatorial and polar radius.

Arguments:
  • a - Equatorial (major) radius (scalar > 0).
  • b - Polar (minor) radius (scalar > 0).
Returns:
The flattening (float or 0).

a_b2f_ (a, b)

 

Return f_, the inverse flattening for a given equatorial and polar radius.

Arguments:
  • a - Equatorial (major) radius (scalar > 0).
  • b - Polar (minor) radius (scalar > 0).
Returns:
The inverse flattening (float or 0).

a_f2b (a, f)

 

Return b, the polar radius for a given equatorial radius and flattening.

Arguments:
  • a - Equatorial (major) radius (scalar > 0).
  • f - Flattening (scalar < 1).
Returns:
The polar (minor) radius (float).

a_f_2b (a, f_)

 

Return b, the polar radius for a given equatorial radius and inverse flattening.

Arguments:
  • a - Equatorial (major) radius (scalar > 0).
  • f_ - Inverse flattening (scalar >>> 1).
Returns:
The polar (minor) radius (float).

b_f2a (b, f)

 

Return a, the equatorial radius for a given polar radius and flattening.

Arguments:
  • b - Polar (minor) radius (scalar > 0).
  • f - Flattening (scalar < 1).
Returns:
The equatorial (major) radius (float).

b_f_2a (b, f_)

 

Return a, the equatorial radius for a given polar radius and inverse flattening.

Arguments:
  • b - Polar (minor) radius (scalar > 0).
  • f_ - Inverse flattening (scalar >>> 1).
Returns:
The equatorial (major) radius (float).

f2e2 (f)

 

Return e2, the eccentricity squared for a given flattening.

Arguments:
  • f - Flattening (scalar < 1).
Returns:
The (1st) eccentricity squared (float < 1).

Note: The result e2 will be negative for prolate ellipsoids.

See Also: Eccentricity conversions and Flattening.

f2e22 (f)

 

Return e22, the 2nd eccentricity squared for a given flattening.

Arguments:
  • f - Flattening (scalar < 1).
Returns:
The 2nd eccentricity squared (float > -1 or INF).

f2e32 (f)

 

Return e32, the 3rd eccentricity squared for a given flattening.

Arguments:
  • f - Flattening (scalar < 1).
Returns:
The 3rd eccentricity squared (float).

f2f2 (f)

 

Return f2, the 2nd flattening for a given flattening.

Arguments:
  • f - Flattening (scalar < 1).
Returns:
The 2nd flattening (float or INF).

f2f_ (f)

 

Return f_, the inverse flattening for a given flattening.

Arguments:
  • f - Flattening (scalar < 1).
Returns:
The inverse flattening (float or 0).

f2n (f)

 

Return n, the 3rd flattening for a given flattening.

Arguments:
  • f - Flattening (scalar < 1).
Returns:
The 3rd flattening (-1 < float < 1).

f_2f (f_)

 

Return f, the flattening for a given inverse flattening.

Arguments:
  • f_ - Inverse flattening (scalar >>> 1).
Returns:
The flattening (float or 0).

n2e2 (n)

 

Return e2, the eccentricity squared for a given 3rd flattening.

Arguments:
  • n - The 3rd flattening (-1 < scalar < 1).
Returns:
The (1st) eccentricity squared (float or -INF).

Note: The result e2 will be negative for prolate ellipsoids.

See Also: Flattening.

n2f (n)

 

Return f, the flattening for a given 3rd flattening.

Arguments:
  • n - The 3rd flattening (-1 <= scalar <= 1).
Returns:
The flattening (float or -INF).

Variables Details

Datums

Value:
Datums.BD72: Datum(name='BD72', ellipsoid=Ellipsoids.Intl1924, transfo\
rm=Transforms.BD72),
Datums.DHDN: Datum(name='DHDN', ellipsoid=Ellipsoids.Bessel1841, trans\
form=Transforms.DHDN),
Datums.ED50: Datum(name='ED50', ellipsoid=Ellipsoids.Intl1924, transfo\
rm=Transforms.ED50),
Datums.GDA2020: Datum(name='GDA2020', ellipsoid=Ellipsoids.GRS80, tran\
sform=Transforms.WGS84),
...

Ellipsoids

Value:
Ellipsoids.Airy1830: Ellipsoid(name='Airy1830', a=6377563.396, b=63562\
56.90923729, f_=299.3249646, f=0.00334085, f2=0.00335205, n=0.00167322\
, e=0.08167337, e2=0.00667054, e22=0.00671533, e32=0.00334643, L=10001\
126.0807165, R1=6370461.23374576, R2=6370459.65470808, R3=6370453.3099\
4572),
Ellipsoids.AiryModified: Ellipsoid(name='AiryModified', a=6377340.189,\
 b=6356034.44793853, f_=299.3249646, f=0.00334085, f2=0.00335205, n=0.\
00167322, e=0.08167337, e2=0.00667054, e22=0.00671533, e32=0.00334643,\
...

Transforms

Value:
Transforms.BD72: Transform(name='BD72', tx=106.86863, ty=-52.29778, tz\
=103.72389, rx=-0, ry=-0, rz=-0.00001, s=1.2727, s1=1, sx=-0.33657, sy\
=-0.45696, sz=-1.84218),
Transforms.Bessel1841: Transform(name='Bessel1841', tx=-582, ty=-105, \
tz=-414, rx=-0.00001, ry=-0, rz=0.00001, s=-8.3, s1=0.99999, sx=-1.04,\
 sy=-0.35, sz=3.08),
Transforms.Clarke1866: Transform(name='Clarke1866', tx=8, ty=-160, tz=\
-176, rx=0, ry=0, rz=0, s=0, s1=1, sx=0, sy=0, sz=0),
...