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# -*- coding: utf-8 -*- 

 

u'''Datums and transformations thereof. 

 

Classes L{Datum} and L{Transform} and registries L{Datums} and 

L{Transforms}, respectively. 

 

Pure Python implementation of geodesy tools for ellipsoidal earth models, 

including datums and ellipsoid parameters for different geographic coordinate 

systems and methods for converting between them and to cartesian coordinates. 

Transcoded from JavaScript originals by I{(C) Chris Veness 2005-2016} and 

published under the same MIT Licence**, see U{latlon-ellipsoidal.js 

<https://www.Movable-Type.co.UK/scripts/geodesy/docs/latlon-ellipsoidal.js.html>}. 

 

Historical geodetic datums: a latitude/longitude point defines a geographic 

location on or above/below the earth’s surface, measured in degrees from 

the equator and the International Reference Meridian and meters above the 

ellipsoid, and based on a given datum. The datum is based on a reference 

ellipsoid and tied to geodetic survey reference points. 

 

Modern geodesy is generally based on the WGS84 datum (as used for instance 

by GPS systems), but previously various reference ellipsoids and datum 

references were used. 

 

The UK Ordnance Survey National Grid References are still based on the otherwise 

historical OSGB36 datum, q.v. U{Ordnance Survey 'A guide to coordinate systems 

in Great Britain', Section 6<https://www.OrdnanceSurvey.co.UK/docs/support/ 

guide-coordinate-systems-great-britain.pdf>}. 

 

@var Datums.BD72: Datum(name='BD72', ellipsoid=Ellipsoids.Intl1924, transform=Transforms.BD72) 

@var Datums.DHDN: Datum(name='DHDN', ellipsoid=Ellipsoids.Bessel1841, transform=Transforms.DHDN) 

@var Datums.ED50: Datum(name='ED50', ellipsoid=Ellipsoids.Intl1924, transform=Transforms.ED50) 

@var Datums.GDA2020: Datum(name='GDA2020', ellipsoid=Ellipsoids.GRS80, transform=Transforms.WGS84) 

@var Datums.GRS80: Datum(name='GRS80', ellipsoid=Ellipsoids.GRS80, transform=Transforms.WGS84) 

@var Datums.Irl1975: Datum(name='Irl1975', ellipsoid=Ellipsoids.AiryModified, transform=Transforms.Irl1975) 

@var Datums.Krassovski1940: Datum(name='Krassovski1940', ellipsoid=Ellipsoids.Krassovski1940, transform=Transforms.Krassovski1940) 

@var Datums.Krassowsky1940: Datum(name='Krassowsky1940', ellipsoid=Ellipsoids.Krassowsky1940, transform=Transforms.Krassowsky1940) 

@var Datums.MGI: Datum(name='MGI', ellipsoid=Ellipsoids.Bessel1841, transform=Transforms.MGI) 

@var Datums.NAD27: Datum(name='NAD27', ellipsoid=Ellipsoids.Clarke1866, transform=Transforms.NAD27) 

@var Datums.NAD83: Datum(name='NAD83', ellipsoid=Ellipsoids.GRS80, transform=Transforms.NAD83) 

@var Datums.NTF: Datum(name='NTF', ellipsoid=Ellipsoids.Clarke1880IGN, transform=Transforms.NTF) 

@var Datums.OSGB36: Datum(name='OSGB36', ellipsoid=Ellipsoids.Airy1830, transform=Transforms.OSGB36) 

@var Datums.Potsdam: Datum(name='Potsdam', ellipsoid=Ellipsoids.Bessel1841, transform=Transforms.Bessel1841) 

@var Datums.Sphere: Datum(name='Sphere', ellipsoid=Ellipsoids.Sphere, transform=Transforms.WGS84) 

@var Datums.TokyoJapan: Datum(name='TokyoJapan', ellipsoid=Ellipsoids.Bessel1841, transform=Transforms.TokyoJapan) 

@var Datums.WGS72: Datum(name='WGS72', ellipsoid=Ellipsoids.WGS72, transform=Transforms.WGS72) 

@var Datums.WGS84: Datum(name='WGS84', ellipsoid=Ellipsoids.WGS84, transform=Transforms.WGS84) 

 

@var 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) 

@var 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) 

@var 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) 

@var Transforms.DHDN: Transform(name='DHDN', tx=-591.28, ty=-81.35, tz=-396.39, rx=0.00001, ry=-0, rz=-0.00001, s=-9.82, s1=0.99999, sx=1.477, sy=-0.0736, sz=-1.458) 

@var Transforms.ED50: Transform(name='ED50', tx=89.5, ty=93.8, tz=123.1, rx=0, ry=0, rz=0, s=-1.2, s1=1, sx=0, sy=0, sz=0.156) 

@var Transforms.Identity: Transform(name='Identity', tx=0, ty=0, tz=0, rx=0, ry=0, rz=0, s=0, s1=1, sx=0, sy=0, sz=0) 

@var Transforms.Irl1965: Transform(name='Irl1965', tx=-482.53, ty=130.596, tz=-564.557, rx=0.00001, ry=0, rz=0, s=-8.15, s1=0.99999, sx=1.042, sy=0.214, sz=0.631) 

@var Transforms.Irl1975: Transform(name='Irl1975', tx=-482.53, ty=130.596, tz=-564.557, rx=-0.00001, ry=-0, rz=-0, s=-1.1, s1=1, sx=-1.042, sy=-0.214, sz=-0.631) 

@var Transforms.Krassovski1940: Transform(name='Krassovski1940', tx=-24, ty=123, tz=94, rx=-0, ry=0, rz=0, s=-2.423, s1=1, sx=-0.02, sy=0.26, sz=0.13) 

@var Transforms.Krassowsky1940: Transform(name='Krassowsky1940', tx=-24, ty=123, tz=94, rx=-0, ry=0, rz=0, s=-2.423, s1=1, sx=-0.02, sy=0.26, sz=0.13) 

@var Transforms.MGI: Transform(name='MGI', tx=-577.326, ty=-90.129, tz=-463.92, rx=0.00002, ry=0.00001, rz=0.00003, s=-2.423, s1=1, sx=5.137, sy=1.474, sz=5.297) 

@var Transforms.NAD27: Transform(name='NAD27', tx=8, ty=-160, tz=-176, rx=0, ry=0, rz=0, s=0, s1=1, sx=0, sy=0, sz=0) 

@var Transforms.NAD83: Transform(name='NAD83', tx=1.004, ty=-1.91, tz=-0.515, rx=0, ry=0, rz=0, s=-0.0015, s1=1, sx=0.0267, sy=0.00034, sz=0.011) 

@var Transforms.NTF: Transform(name='NTF', tx=-168, ty=-60, tz=320, rx=0, ry=0, rz=0, s=0, s1=1, sx=0, sy=0, sz=0) 

@var Transforms.OSGB36: Transform(name='OSGB36', tx=-446.448, ty=125.157, tz=-542.06, rx=-0, ry=-0, rz=-0, s=20.4894, s1=1.00002, sx=-0.1502, sy=-0.247, sz=-0.8421) 

@var Transforms.TokyoJapan: Transform(name='TokyoJapan', tx=148, ty=-507, tz=-685, rx=0, ry=0, rz=0, s=0, s1=1, sx=0, sy=0, sz=0) 

@var Transforms.WGS72: Transform(name='WGS72', tx=0, ty=0, tz=-4.5, rx=0, ry=0, rz=0, s=-0.22, s1=1, sx=0, sy=0, sz=0.554) 

@var Transforms.WGS84: Transform(name='WGS84', tx=0, ty=0, tz=0, rx=0, ry=0, rz=0, s=0, s1=1, sx=0, sy=0, sz=0) 

''' 

# make sure int/int division yields float quotient, see .basics 

from __future__ import division 

 

from pygeodesy.basics import isscalar, neg_, _xinstanceof 

from pygeodesy.ellipsoids import a_f2Tuple, _4Ecef, Ellipsoid, \ 

Ellipsoid2, Ellipsoids, Vector3Tuple 

# from pygeodesy.errors import _IsnotError # from .fmath 

from pygeodesy.fmath import fdot, fmean, Fmt, _IsnotError 

from pygeodesy.interns import NN, _Airy1830_, _AiryModified_, _Bessel1841_, \ 

_Clarke1866_, _Clarke1880IGN_, _COMMASPACE_, \ 

_DOT_, _ellipsoid_, _ellipsoidal_, _float as _F, \ 

_GRS80_, _Intl1924_, _Krassovski1940_, _NAD27_, \ 

_Krassowsky1940_, _NAD83_, _name_, _s_, _Sphere_, \ 

_spherical_, _sx_, _sy_, _sz_, _transform_, \ 

_tx_, _ty_, _tz_, _UNDER_, _WGS72_, _WGS84_, \ 

_0_0, _0_26, _1_0, _2_0, _8_0, _3600_0 

from pygeodesy.lazily import _ALL_LAZY 

from pygeodesy.named import _NamedEnum, _NamedEnumItem, \ 

_lazyNamedEnumItem as _lazy, Property_RO 

# from pygeodesy.namedTuples import Vector3Tuple # from .ellipsoids 

# from pygeodesy.props import Property_RO # from .named 

# from pygeodesy.streprs import Fmt # from .fmath 

from pygeodesy.units import Radius_ 

 

from math import radians 

 

__all__ = _ALL_LAZY.datums 

__version__ = '21.10.05' 

 

_BD72_ = 'BD72' 

_DHDN_ = 'DHDN' 

_ED50_ = 'ED50' 

_GDA2020_ = 'GDA2020' 

_Identity_ = 'Identity' 

_Inverse_ = 'Inverse' 

_Irl1965_ = 'Irl1965' 

_Irl1975_ = 'Irl1975' 

_MGI_ = 'MGI' 

_NTF_ = 'NTF' 

_OSGB36_ = 'OSGB36' 

_Potsdam_ = 'Potsdam' 

_TokyoJapan_ = 'TokyoJapan' 

 

 

def _r_s2(s_): 

'''(INTERNAL) rotation in C{radians} and C{degree seconds}. 

''' 

return _F(radians(s_ / _3600_0)), s_ 

 

 

class Transform(_NamedEnumItem): 

'''Helmert transformation. 

 

@see: L{Transform7Tuple}. 

''' 

tx = _0_0 # x translation (C{meter}) 

ty = _0_0 # y translation (C{meter}) 

tz = _0_0 # z translation (C{meter}) 

 

rx = _0_0 # x rotation (C{radians}) 

ry = _0_0 # y rotation (C{radians}) 

rz = _0_0 # z rotation (C{radians}) 

 

s = _0_0 # scale ppm (C{float}) 

s1 = _1_0 # scale + 1 (C{float}) 

 

sx = _0_0 # x rotation (degree seconds) 

sy = _0_0 # y rotation (degree seconds) 

sz = _0_0 # z rotation (degree seconds) 

 

def __init__(self, name=NN, tx=0, ty=0, tz=0, 

sx=0, sy=0, sz=0, s=0): 

'''New L{Transform}. 

 

@kwarg name: Optional, unique name (C{str}). 

@kwarg tx: Optional X translation (C{meter}). 

@kwarg ty: Optional Y translation (C{meter}). 

@kwarg tz: Optional Z translation (C{meter}). 

@kwarg s: Optional scale (C{float}), ppm. 

@kwarg sx: Optional X rotation (C{degree seconds}). 

@kwarg sy: Optional Y rotation (C{degree seconds}). 

@kwarg sz: Optional Z rotation (C{degree seconds}). 

 

@raise NameError: Transform with that B{C{name}} already exists. 

''' 

if tx: 

self.tx = tx 

if ty: 

self.ty = ty 

if tz: 

self.tz = tz 

if sx: # secs to rads 

self.rx, self.sx = _r_s2(sx) 

if sy: 

self.ry, self.sy = _r_s2(sy) 

if sz: 

self.rz, self.sz = _r_s2(sz) 

if s: 

self.s = s 

self.s1 = _F(s * 1e-6 + _1_0) # normalize ppm to (s + 1) 

 

self._register(Transforms, name) 

 

def __eq__(self, other): 

'''Compare this and an other transform. 

 

@arg other: The other transform (L{Transform}). 

 

@return: C{True} if equal, C{False} otherwise. 

''' 

return self is other or (isinstance(other, Transform) and 

self.tx == other.tx and 

self.ty == other.ty and 

self.tz == other.tz and 

self.rx == other.rx and 

self.ry == other.ry and 

self.rz == other.rz and 

self.s == other.s) 

 

def inverse(self, name=NN): 

'''Return the inverse of this transform. 

 

@kwarg name: Optional, unique name (C{str}). 

 

@return: Inverse (Transform). 

 

@raise NameError: Transform with that B{C{name}} already exists. 

''' 

return Transform(name=name or (self.name + _Inverse_), 

tx=-self.tx, ty=-self.ty, tz=-self.tz, 

sx=-self.sx, sy=-self.sy, sz=-self.sz, s=-self.s) 

 

def toStr(self, prec=5): # PYCHOK expected 

'''Return this transform as a string. 

 

@kwarg prec: Optional number of decimals, unstripped (C{int}). 

 

@return: Transform attributes (C{str}). 

''' 

return self._instr(prec, _tx_, _ty_, _tz_, 

'rx', 'ry', 'rz', _s_, 's1', 

_sx_, _sy_, _sz_) 

 

def transform(self, x, y, z, inverse=False): 

'''Transform a (geocentric) Cartesian point, forward or inverse. 

 

@arg x: X coordinate (C{meter}). 

@arg y: Y coordinate (C{meter}). 

@arg z: Z coordinate (C{meter}). 

@kwarg inverse: Optional direction, forward or inverse (C{bool}). 

 

@return: A L{Vector3Tuple}C{(x, y, z)}, transformed. 

''' 

if inverse: 

_xyz = neg_(_1_0, x, y, z) 

_s1 = self.s1 - _2_0 # == -(1 - s * 1e-6)) == -(1 - (s1 - 1)) 

else: 

_xyz = _1_0, x, y, z 

_s1 = self.s1 

# x', y', z' = (.tx + x * .s1 - y * .rz + z * .ry, 

# .ty + x * .rz + y * .s1 - z * .rx, 

# .tz - x * .ry + y * .rx + z * .s1) 

return Vector3Tuple(fdot(_xyz, self.tx, _s1, -self.rz, self.ry), 

fdot(_xyz, self.ty, self.rz, _s1, -self.rx), 

fdot(_xyz, self.tz, -self.ry, self.rx, _s1), 

name=self.name) 

 

 

class Transforms(_NamedEnum): 

'''(INTERNAL) L{Transform} registry, I{must} be a sub-class 

to accommodate the L{_LazyNamedEnumItem} properties. 

''' 

def _Lazy(self, **name_tx_ty_tz_sx_sy_sz_s): 

'''(INTERNAL) Instantiate the C{Transform}. 

''' 

return Transform(**name_tx_ty_tz_sx_sy_sz_s) 

 

Transforms = Transforms(Transform) # PYCHOK singleton 

'''Some pre-defined L{Transform}s, all I{lazily} instantiated.''' 

# <https://WikiPedia.org/wiki/Helmert_transformation> from WGS84 

Transforms._assert( 

BD72 = _lazy(_BD72_, tx=_F(106.868628), ty=_F(-52.297783), tz=_F(103.723893), 

# <https://www.NGI.BE/FR/FR4-4.shtm> ETRS89 == WG84 

# <https://GeoRepository.com/transformation_15929/BD72-to-WGS-84-3.html> 

sx=_F(-0.33657), sy=_F( -0.456955), sz=_F( -1.84218), 

s=_F( 1.2727)), 

Bessel1841 = _lazy(_Bessel1841_, tx=_F(-582.0), ty=_F(-105.0), tz=_F(-414.0), 

sx=_F( -1.04), sy=_F( -0.35), sz=_F( 3.08), 

s=_F( -8.3)), 

Clarke1866 = _lazy(_Clarke1866_, tx=_F(8), ty=_F(-160), tz=_F(-176)), 

DHDN = _lazy(_DHDN_, tx=_F(-591.28), ty=_F(-81.35), tz=_F(-396.39), 

sx=_F( 1.477), sy=_F( -0.0736), sz=_F( -1.458), 

s=_F( -9.82)), # Germany 

ED50 = _lazy(_ED50_, tx=_F(89.5), ty=_F(93.8), tz=_F(123.1), 

# <https://GeoNet.ESRI.com/thread/36583> sz=_F(-0.156) 

# <https://GitHub.com/ChrisVeness/geodesy/blob/master/latlon-ellipsoidal.js> 

# <https://www.Gov.UK/guidance/oil-and-gas-petroleum-operations-notices#pon-4> 

sz=_F( 0.156), s=_F(-1.2)), 

Identity = _lazy(_Identity_), 

Irl1965 = _lazy(_Irl1965_, tx=_F(-482.530), ty=_F(130.596), tz=_F(-564.557), 

sx=_F( 1.042), sy=_F( 0.214), sz=_F( 0.631), 

s=_F( -8.15)), 

Irl1975 = _lazy(_Irl1975_, tx=_F(-482.530), ty=_F(130.596), tz=_F(-564.557), 

# XXX rotation signs may be opposite, to be checked 

sx=_F( -1.042), sy=_F( -0.214), sz=_F( -0.631), 

s=_F( -1.1)), 

Krassovski1940 = _lazy(_Krassovski1940_, tx=_F(-24.0), ty=_F(123.0), tz=_F(94.0), 

sx=_F( -0.02), sy= _0_26, sz=_F( 0.13), 

s=_F( -2.423)), # spelling 

Krassowsky1940 = _lazy(_Krassowsky1940_, tx=_F(-24.0), ty=_F(123.0), tz=_F(94.0), 

sx=_F( -0.02), sy= _0_26, sz=_F( 0.13), 

s=_F( -2.423)), # spelling 

MGI = _lazy(_MGI_, tx=_F(-577.326), ty=_F(-90.129), tz=_F(-463.920), 

sx=_F( 5.137), sy=_F( 1.474), sz=_F( 5.297), 

s=_F( -2.423)), # Austria 

NAD27 = _lazy(_NAD27_, tx=_8_0, ty=_F(-160), tz=_F(-176)), 

NAD83 = _lazy(_NAD83_, tx=_F( 1.004), ty=_F(-1.910), tz=_F(-0.515), 

sx=_F( 0.0267), sy=_F( 0.00034), sz=_F( 0.011), 

s=_F(-0.0015)), 

NTF = _lazy(_NTF_, tx=_F(-168), ty=_F(-60), tz=_F(320)), # XXX verify 

OSGB36 = _lazy(_OSGB36_, tx=_F(-446.448), ty=_F(125.157), tz=_F(-542.060), 

sx=_F( -0.1502), sy=_F( -0.2470), sz=_F( -0.8421), 

s=_F( 20.4894)), 

TokyoJapan = _lazy(_TokyoJapan_, tx=_F(148), ty=_F(-507), tz=_F(-685)), 

WGS72 = _lazy(_WGS72_, tz=_F(-4.5), sz=_F(0.554), s=_F(-0.22)), 

WGS84 = _lazy(_WGS84_), # unity 

) 

 

 

class Datum(_NamedEnumItem): 

'''Ellipsoid and transform parameters for an earth model. 

''' 

_ellipsoid = Ellipsoids.WGS84 # default ellipsoid (L{Ellipsoid}, L{Ellipsoid2}) 

_transform = Transforms.WGS84 # default transform (L{Transform}) 

 

def __init__(self, ellipsoid, transform=None, name=NN): 

'''New L{Datum}. 

 

@arg ellipsoid: The ellipsoid (L{Ellipsoid} or L{Ellipsoid2}). 

@kwarg transform: Optional transform (L{Transform}). 

@kwarg name: Optional, unique name (C{str}). 

 

@raise NameError: Datum with that B{C{name}} already exists. 

 

@raise TypeError: If B{C{ellipsoid}} is not an L{Ellipsoid} 

nor L{Ellipsoid2} or B{C{transform}} is 

not a L{Transform}. 

''' 

self._ellipsoid = ellipsoid or Datum._ellipsoid 

_xinstanceof(Ellipsoid, ellipsoid=self.ellipsoid) 

 

self._transform = transform or Datum._transform 

_xinstanceof(Transform, transform=self.transform) 

 

self._register(Datums, name or self.transform.name or self.ellipsoid.name) 

 

def __eq__(self, other): 

'''Compare this and an other datum. 

 

@arg other: The other datum (L{Datum}). 

 

@return: C{True} if equal, C{False} otherwise. 

''' 

return self is other or (isinstance(other, Datum) and 

self.ellipsoid == other.ellipsoid and 

self.transform == other.transform) 

 

def ecef(self, Ecef=None): 

'''Return U{ECEF<https://WikiPedia.org/wiki/ECEF>} converter. 

 

@kwarg Ecef: ECEF class to use (L{EcefKarney}, L{EcefVeness} 

or L{EcefYou}). 

 

@return: An ECEF converter for this C{datum} (L{EcefKarney}, 

L{EcefVeness} or L{EcefYou}). 

 

@raise TypeError: Invalid B{C{Ecef}}. 

''' 

return _4Ecef(self, Ecef) 

 

@Property_RO 

def ellipsoid(self): 

'''Get this datum's ellipsoid (L{Ellipsoid} or L{Ellipsoid2}). 

''' 

return self._ellipsoid 

 

@Property_RO 

def exactTM(self): 

'''Get the C{ExactTM} projection (L{ExactTransverseMercator}). 

''' 

from pygeodesy.etm import ExactTransverseMercator 

return ExactTransverseMercator(datum=self) 

 

@Property_RO 

def isEllipsoidal(self): 

'''Check whether this datum is ellipsoidal (C{bool}). 

''' 

return self._ellipsoid.isEllipsoidal 

 

@Property_RO 

def isOblate(self): 

'''Check whether this datum's ellipsoidal is I{oblate} (C{bool}). 

''' 

return self._ellipsoid.isOblate 

 

@Property_RO 

def isProlate(self): 

'''Check whether this datum's ellipsoidal is I{prolate} (C{bool}). 

''' 

return self._ellipsoid.isProlate 

 

@Property_RO 

def isSpherical(self): 

'''Check whether this datum is (near-)spherical (C{bool}). 

''' 

return self._ellipsoid.isSpherical 

 

def toStr(self, **unused): # PYCHOK expected 

'''Return this datum as a string. 

 

@return: Datum attributes (C{str}). 

''' 

t = [Fmt.EQUAL(_name_, repr(self.named))] 

for a in (_ellipsoid_, _transform_): 

v = getattr(self, a) 

t.append(NN(Fmt.EQUAL(a, v.classname), _s_, _DOT_, v.name)) 

return _COMMASPACE_.join(t) 

 

@Property_RO 

def transform(self): 

'''Get this datum's transform (L{Transform}). 

''' 

return self._transform 

 

 

def _En2(earth, name): 

'''(INTERNAL) Helper for C{_ellipsoid} and C{_ellipsoidal_datum}. 

''' 

if isinstance(earth, (Ellipsoid, Ellipsoid2)): 

E = earth 

n = NN(_UNDER_, name or E.name) 

elif isinstance(earth, Datum): 

E = earth.ellipsoid 

n = NN(_UNDER_, name or earth.name) 

elif isinstance(earth, a_f2Tuple): 

n = NN(_UNDER_, name or earth.name) 

E = Ellipsoid(earth.a, earth.b, name=n) 

elif isinstance(earth, (tuple, list)) and len(earth) == 2: # no cover 

n = NN(_UNDER_, name or getattr(earth, _name_, NN)) 

a_f = a_f2Tuple(*earth) 

E = Ellipsoid(a_f.a, a_f.b, name=n) # PYCHOK .a 

else: 

E, n = None, NN 

return E, n 

 

 

def _ellipsoid(earth, name=NN): # in .trf 

'''(INTERNAL) Create an L{Ellipsoid} or L{Ellipsoid2} from L{Datum} or C{a_f2Tuple}. 

''' 

E, _ = _En2(earth, name) 

if not E: 

_xinstanceof(Ellipsoid, Ellipsoid2, a_f2Tuple, Datum, earth=earth) 

return E 

 

 

def _ellipsoidal_datum(earth, name=NN, raiser=False): 

'''(INTERNAL) Create a L{Datum} from an L{Ellipsoid} or L{Ellipsoid2} or C{a_f2Tuple}. 

''' 

if isinstance(earth, Datum): 

d = earth 

else: 

E, n = _En2(earth, name) 

if not E: 

_xinstanceof(Datum, Ellipsoid, Ellipsoid2, a_f2Tuple, earth=earth) 

d = Datum(E, transform=Transforms.Identity, name=n) 

if raiser and not d.isEllipsoidal: 

raise _IsnotError(_ellipsoidal_, earth=earth) 

return d 

 

 

def _mean_radius(radius, *lats): 

'''(INTERNAL) Compute the mean radius of a L{Datum} from an L{Ellipsoid}, 

L{Ellipsoid2} or scalar earth C{radius} for several latitudes. 

''' 

if isscalar(radius): 

r = Radius_(radius, low=0, Error=TypeError) 

else: # no cover 

E = _ellipsoidal_datum(radius).ellipsoid 

r = fmean(map(E.Rgeocentric, lats)) if lats else E.Rmean 

return r 

 

 

def _spherical_datum(earth, name=NN, raiser=False): 

'''(INTERNAL) Create a L{Datum} from an L{Ellipsoid}, L{Ellipsoid2} or scalar earth C{radius}. 

''' 

if isscalar(earth): 

n = NN(_UNDER_, name) 

r = Radius_(earth, Error=TypeError) 

E = Ellipsoid(r, r, name=n) 

d = Datum(E, transform=Transforms.Identity, name=n) 

else: 

d = _ellipsoidal_datum(earth, name=name) 

if raiser and not d.isSpherical: 

raise _IsnotError(_spherical_, earth=earth) 

return d 

 

 

class Datums(_NamedEnum): 

'''(INTERNAL) L{Datum} registry, I{must} be a sub-class 

to accommodate the L{_LazyNamedEnumItem} properties. 

''' 

def _Lazy(self, ellipsoid_name, transform_name, name=NN): 

'''(INTERNAL) Instantiate the L{Datum}. 

''' 

return Datum(Ellipsoids.get(ellipsoid_name), 

Transforms.get(transform_name), name=name) 

 

Datums = Datums(Datum) # PYCHOK singleton 

'''Some pre-defined L{Datum}s, all I{lazily} instantiated.''' 

# Datums with associated ellipsoid and Helmert transform parameters 

# to convert from WGS84 into the given datum. More are available at 

# <https://Earth-Info.NGA.mil/GandG/coordsys/datums/NATO_DT.pdf> and 

# <XXX://www.FieldenMaps.info/cconv/web/cconv_params.js>. 

Datums._assert( 

# Belgian Datum 1972, based on Hayford ellipsoid. 

# <https://NL.WikiPedia.org/wiki/Belgian_Datum_1972> 

# <https://SpatialReference.org/ref/sr-org/7718/html/> 

BD72 = _lazy(_BD72_, _Intl1924_, _BD72_), 

 

# Germany <https://WikiPedia.org/wiki/Bessel-Ellipsoid> 

# <https://WikiPedia.org/wiki/Helmert_transformation> 

DHDN = _lazy(_DHDN_, _Bessel1841_, _DHDN_), 

 

# <https://www.Gov.UK/guidance/oil-and-gas-petroleum-operations-notices#pon-4> 

ED50 = _lazy(_ED50_, _Intl1924_, _ED50_), 

 

# Australia <https://ICSM.Gov.AU/datum/gda2020-and-gda94-technical-manuals> 

# ADG66 = _lazy(_ADG66_, _ANS_, _WGS84_), # XXX Transform? 

# ADG84 = _lazy(_ADG84_, _ANS_, _WGS84_), # XXX Transform? 

# GDA94 = _lazy(_GDA94_, _GRS80_, _WGS84_), 

GDA2020 = _lazy(_GDA2020_, _GRS80_, _WGS84_), # XXX Transform? 

 

# <https://WikiPedia.org/wiki/GRS_80> 

GRS80 = _lazy(_GRS80_, _GRS80_, _WGS84_), 

 

# <https://OSI.IE/OSI/media/OSI/Content/Publications/transformations_booklet.pdf> 

# Irl1975 = _lazy(_Irl1965_, _AiryModified_, _Irl1965_), 

Irl1975 = _lazy(_Irl1975_, _AiryModified_, _Irl1975_), 

 

# Germany <https://WikiPedia.org/wiki/Helmert_transformation> 

Krassovski1940 = _lazy(_Krassovski1940_, _Krassovski1940_, _Krassovski1940_), # XXX spelling? 

Krassowsky1940 = _lazy(_Krassowsky1940_, _Krassowsky1940_, _Krassowsky1940_), # XXX spelling? 

 

# Austria <https://DE.WikiPedia.org/wiki/Datum_Austria> 

MGI = _lazy(_MGI_, _Bessel1841_, _MGI_), 

 

# <https://WikiPedia.org/wiki/Helmert_transformation> 

NAD27 = _lazy(_NAD27_, _Clarke1866_, _NAD27_), 

 

# NAD83 (2009) == WGS84 - <https://www.UVM.edu/giv/resources/WGS84_NAD83.pdf> 

# (If you *really* must convert WGS84<->NAD83, you need more than this!) 

NAD83 = _lazy(_NAD83_, _GRS80_, _NAD83_), 

 

# Nouvelle Triangulation Francaise (Paris) XXX verify 

NTF = _lazy(_NTF_, _Clarke1880IGN_, _NTF_), 

 

# <https://www.OrdnanceSurvey.co.UK/docs/support/guide-coordinate-systems-great-britain.pdf> 

OSGB36 = _lazy(_OSGB36_, _Airy1830_, _OSGB36_), 

 

# Germany <https://WikiPedia.org/wiki/Helmert_transformation> 

Potsdam = _lazy(_Potsdam_, _Bessel1841_, _Bessel1841_), 

 

# XXX psuedo-ellipsoids for spherical LatLon 

Sphere = _lazy(_Sphere_, _Sphere_, _WGS84_), 

 

# <https://www.GeoCachingToolbox.com?page=datumEllipsoidDetails> 

TokyoJapan = _lazy(_TokyoJapan_, _Bessel1841_, _TokyoJapan_), 

 

# <https://www.ICAO.int/safety/pbn/documentation/eurocontrol/eurocontrol%20wgs%2084%20implementation%20manual.pdf> 

WGS72 = _lazy(_WGS72_, _WGS72_, _WGS72_), 

 

WGS84 = _lazy(_WGS84_, _WGS84_, _WGS84_), 

) 

 

_WGS84 = Datums.WGS84 # PYCHOK exported internally 

 

if __name__ == '__main__': 

 

from pygeodesy.interns import _COMMA_, _NL_, _NL_var_ 

 

# __doc__ of this file, force all into registery 

for r in (Datums, Transforms): 

t = [NN] + r.toRepr(all=True).split(_NL_) 

print(_NL_var_.join(i.strip(_COMMA_) for i in t)) 

 

# **) MIT License 

# 

# Copyright (C) 2016-2022 -- mrJean1 at Gmail -- All Rights Reserved. 

# 

# Permission is hereby granted, free of charge, to any person obtaining a 

# copy of this software and associated documentation files (the "Software"), 

# to deal in the Software without restriction, including without limitation 

# the rights to use, copy, modify, merge, publish, distribute, sublicense, 

# and/or sell copies of the Software, and to permit persons to whom the 

# Software is furnished to do so, subject to the following conditions: 

# 

# The above copyright notice and this permission notice shall be included 

# in all copies or substantial portions of the Software. 

# 

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS 

# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 

# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 

# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR 

# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, 

# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR 

# OTHER DEALINGS IN THE SOFTWARE.