import numpy as np
from . import Lambert
P = -1
def iszero(a):
return np.isclose(a,0.0,atol=1.0e-12,rtol=0.0)
class Rotation:
u"""
Orientation stored with functionality for conversion to different representations.
References
----------
D. Rowenhorst et al., Modelling and Simulation in Materials Science and Engineering 23:083501, 2015
https://doi.org/10.1088/0965-0393/23/8/083501
Conventions
-----------
Convention 1: Coordinate frames are right-handed.
Convention 2: A rotation angle ω is taken to be positive for a counterclockwise rotation
when viewing from the end point of the rotation axis towards the origin.
Convention 3: Rotations will be interpreted in the passive sense.
Convention 4: Euler angle triplets are implemented using the Bunge convention,
with the angular ranges as [0, 2π],[0, π],[0, 2π].
Convention 5: The rotation angle ω is limited to the interval [0, π].
Convention 6: the real part of a quaternion is positive, Re(q) > 0
Convention 7: P = -1 (as default).
Usage
-----
Vector "a" (defined in coordinate system "A") is passively rotated
resulting in new coordinates "b" when expressed in system "B".
b = Q * a
b = np.dot(Q.asMatrix(),a)
"""
__slots__ = ['quaternion']
def __init__(self,quaternion = np.array([1.0,0.0,0.0,0.0])):
"""
Initializes to identity unless specified.
Parameters
----------
quaternion : numpy.ndarray, optional
Unit quaternion that follows the conventions. Use .fromQuaternion to perform a sanity check.
"""
self.quaternion = quaternion.copy()
def __copy__(self):
"""Copy."""
return self.__class__(self.quaternion)
copy = __copy__
def __repr__(self):
"""Orientation displayed as unit quaternion, rotation matrix, and Bunge-Euler angles."""
return '\n'.join([
'Quaternion: (real={:.3f}, imag=<{:+.3f}, {:+.3f}, {:+.3f}>)'.format(*(self.quaternion)),
'Matrix:\n{}'.format(self.asMatrix()),
'Bunge Eulers / deg: ({:3.2f}, {:3.2f}, {:3.2f})'.format(*self.asEulers(degrees=True)),
])
def __mul__(self, other):
"""
Multiplication.
Parameters
----------
other : numpy.ndarray or Rotation
Vector, second or fourth order tensor, or rotation object that is rotated.
Todo
----
Document details active/passive)
considere rotation of (3,3,3,3)-matrix
"""
if isinstance(other, Rotation): # rotate a rotation
self_q = self.quaternion[0]
self_p = self.quaternion[1:]
other_q = other.quaternion[0]
other_p = other.quaternion[1:]
R = self.__class__(np.append(self_q*other_q - np.dot(self_p,other_p),
self_q*other_p + other_q*self_p + P * np.cross(self_p,other_p)))
return R.standardize()
elif isinstance(other, (tuple,np.ndarray)):
if isinstance(other,tuple) or other.shape == (3,): # rotate a single (3)-vector or meshgrid
A = self.quaternion[0]**2.0 - np.dot(self.quaternion[1:],self.quaternion[1:])
B = 2.0 * ( self.quaternion[1]*other[0]
+ self.quaternion[2]*other[1]
+ self.quaternion[3]*other[2])
C = 2.0 * P*self.quaternion[0]
return np.array([
A*other[0] + B*self.quaternion[1] + C*(self.quaternion[2]*other[2] - self.quaternion[3]*other[1]),
A*other[1] + B*self.quaternion[2] + C*(self.quaternion[3]*other[0] - self.quaternion[1]*other[2]),
A*other[2] + B*self.quaternion[3] + C*(self.quaternion[1]*other[1] - self.quaternion[2]*other[0]),
])
elif other.shape == (3,3,): # rotate a single (3x3)-matrix
return np.dot(self.asMatrix(),np.dot(other,self.asMatrix().T))
elif other.shape == (3,3,3,3,):
raise NotImplementedError
else:
return NotImplemented
else:
return NotImplemented
def inverse(self):
"""In-place inverse rotation/backward rotation."""
self.quaternion[1:] *= -1
return self
def inversed(self):
"""Inverse rotation/backward rotation."""
return self.copy().inverse()
def standardize(self):
"""In-place quaternion representation with positive q."""
if self.quaternion[0] < 0.0: self.quaternion*=-1
return self
def standardized(self):
"""Quaternion representation with positive q."""
return self.copy().standardize()
def misorientation(self,other):
"""
Get Misorientation.
Parameters
----------
other : Rotation
Rotation to which the misorientation is computed.
"""
return other*self.inversed()
def average(self,other):
"""
Calculate the average rotation.
Parameters
----------
other : Rotation
Rotation from which the average is rotated.
"""
return Rotation.fromAverage([self,other])
################################################################################################
# convert to different orientation representations (numpy arrays)
def asQuaternion(self):
"""
Unit quaternion [q, p_1, p_2, p_3] unless quaternion == True: damask.quaternion object.
Parameters
----------
quaternion : bool, optional
return quaternion as DAMASK object.
"""
return self.quaternion
def asEulers(self,
degrees = False):
"""
Bunge-Euler angles: (φ_1, ϕ, φ_2).
Parameters
----------
degrees : bool, optional
return angles in degrees.
"""
eu = Rotation.qu2eu(self.quaternion)
if degrees: eu = np.degrees(eu)
return eu
def asAxisAngle(self,
degrees = False,
pair = False):
"""
Axis angle representation [n_1, n_2, n_3, ω] unless pair == True: ([n_1, n_2, n_3], ω).
Parameters
----------
degrees : bool, optional
return rotation angle in degrees.
pair : bool, optional
return tuple of axis and angle.
"""
ax = Rotation.qu2ax(self.quaternion)
if degrees: ax[3] = np.degrees(ax[3])
return (ax[:3],np.degrees(ax[3])) if pair else ax
def asMatrix(self):
"""Rotation matrix."""
return Rotation.qu2om(self.quaternion)
def asRodrigues(self,
vector = False):
"""
Rodrigues-Frank vector representation [n_1, n_2, n_3, tan(ω/2)] unless vector == True: [n_1, n_2, n_3] * tan(ω/2).
Parameters
----------
vector : bool, optional
return as actual Rodrigues--Frank vector, i.e. rotation axis scaled by tan(ω/2).
"""
ro = Rotation.qu2ro(self.quaternion)
return ro[:3]*ro[3] if vector else ro
def asHomochoric(self):
"""Homochoric vector: (h_1, h_2, h_3)."""
return Rotation.qu2ho(self.quaternion)
def asCubochoric(self):
"""Cubochoric vector: (c_1, c_2, c_3)."""
return Rotation.qu2cu(self.quaternion)
def asM(self):
"""
Intermediate representation supporting quaternion averaging.
References
----------
F. Landis Markley et al., Journal of Guidance, Control, and Dynamics 30(4):1193-1197, 2007
https://doi.org/10.2514/1.28949
"""
return np.outer(self.quaternion,self.quaternion)
################################################################################################
# static constructors. The input data needs to follow the convention, options allow to
# relax these convections
@staticmethod
def fromQuaternion(quaternion,
acceptHomomorph = False,
P = -1):
qu = quaternion if isinstance(quaternion,np.ndarray) and quaternion.dtype == np.dtype(float) \
else np.array(quaternion,dtype=float)
if P > 0: qu[1:4] *= -1 # convert from P=1 to P=-1
if qu[0] < 0.0:
if acceptHomomorph:
qu *= -1.
else:
raise ValueError('Quaternion has negative first component.\n{}'.format(qu[0]))
if not np.isclose(np.linalg.norm(qu), 1.0):
raise ValueError('Quaternion is not of unit length.\n{} {} {} {}'.format(*qu))
return Rotation(qu)
@staticmethod
def fromEulers(eulers,
degrees = False):
eu = eulers if isinstance(eulers, np.ndarray) and eulers.dtype == np.dtype(float) \
else np.array(eulers,dtype=float)
eu = np.radians(eu) if degrees else eu
if np.any(eu < 0.0) or np.any(eu > 2.0*np.pi) or eu[1] > np.pi:
raise ValueError('Euler angles outside of [0..2π],[0..π],[0..2π].\n{} {} {}.'.format(*eu))
return Rotation(Rotation.eu2qu(eu))
@staticmethod
def fromAxisAngle(angleAxis,
degrees = False,
normalise = False,
P = -1):
ax = angleAxis if isinstance(angleAxis, np.ndarray) and angleAxis.dtype == np.dtype(float) \
else np.array(angleAxis,dtype=float)
if P > 0: ax[0:3] *= -1 # convert from P=1 to P=-1
if degrees: ax[ 3] = np.radians(ax[3])
if normalise: ax[0:3] /= np.linalg.norm(ax[0:3])
if ax[3] < 0.0 or ax[3] > np.pi:
raise ValueError('Axis angle rotation angle outside of [0..π].\n'.format(ax[3]))
if not np.isclose(np.linalg.norm(ax[0:3]), 1.0):
raise ValueError('Axis angle rotation axis is not of unit length.\n{} {} {}'.format(*ax[0:3]))
return Rotation(Rotation.ax2qu(ax))
@staticmethod
def fromBasis(basis,
orthonormal = True,
reciprocal = False,
):
om = basis if isinstance(basis, np.ndarray) else np.array(basis).reshape((3,3))
if reciprocal:
om = np.linalg.inv(om.T/np.pi) # transform reciprocal basis set
orthonormal = False # contains stretch
if not orthonormal:
(U,S,Vh) = np.linalg.svd(om) # singular value decomposition
om = np.dot(U,Vh)
if not np.isclose(np.linalg.det(om),1.0):
raise ValueError('matrix is not a proper rotation.\n{}'.format(om))
if not np.isclose(np.dot(om[0],om[1]), 0.0) \
or not np.isclose(np.dot(om[1],om[2]), 0.0) \
or not np.isclose(np.dot(om[2],om[0]), 0.0):
raise ValueError('matrix is not orthogonal.\n{}'.format(om))
return Rotation(Rotation.om2qu(om))
@staticmethod
def fromMatrix(om,
):
return Rotation.fromBasis(om)
@staticmethod
def fromRodrigues(rodrigues,
normalise = False,
P = -1):
ro = rodrigues if isinstance(rodrigues, np.ndarray) and rodrigues.dtype == np.dtype(float) \
else np.array(rodrigues,dtype=float)
if P > 0: ro[0:3] *= -1 # convert from P=1 to P=-1
if normalise: ro[0:3] /= np.linalg.norm(ro[0:3])
if not np.isclose(np.linalg.norm(ro[0:3]), 1.0):
raise ValueError('Rodrigues rotation axis is not of unit length.\n{} {} {}'.format(*ro[0:3]))
if ro[3] < 0.0:
raise ValueError('Rodrigues rotation angle not positive.\n'.format(ro[3]))
return Rotation(Rotation.ro2qu(ro))
@staticmethod
def fromHomochoric(homochoric,
P = -1):
ho = homochoric if isinstance(homochoric, np.ndarray) and homochoric.dtype == np.dtype(float) \
else np.array(homochoric,dtype=float)
if P > 0: ho *= -1 # convert from P=1 to P=-1
return Rotation(Rotation.ho2qu(ho))
@staticmethod
def fromCubochoric(cubochoric,
P = -1):
cu = cubochoric if isinstance(cubochoric, np.ndarray) and cubochoric.dtype == np.dtype(float) \
else np.array(cubochoric,dtype=float)
ho = Rotation.cu2ho(cu)
if P > 0: ho *= -1 # convert from P=1 to P=-1
return Rotation(Rotation.ho2qu(ho))
@staticmethod
def fromAverage(rotations,
weights = []):
"""
Average rotation.
References
----------
F. Landis Markley et al., Journal of Guidance, Control, and Dynamics 30(4):1193-1197, 2007
https://doi.org/10.2514/1.28949
Parameters
----------
rotations : list of Rotations
Rotations to average from
weights : list of floats, optional
Weights for each rotation used for averaging
"""
if not all(isinstance(item, Rotation) for item in rotations):
raise TypeError("Only instances of Rotation can be averaged.")
N = len(rotations)
if weights == [] or not weights:
weights = np.ones(N,dtype='i')
for i,(r,n) in enumerate(zip(rotations,weights)):
M = r.asM() * n if i == 0 \
else M + r.asM() * n # noqa add (multiples) of this rotation to average noqa
eig, vec = np.linalg.eig(M/N)
return Rotation.fromQuaternion(np.real(vec.T[eig.argmax()]),acceptHomomorph = True)
@staticmethod
def fromRandom():
r = np.random.random(3)
A = np.sqrt(r[2])
B = np.sqrt(1.0-r[2])
return Rotation(np.array([np.cos(2.0*np.pi*r[0])*A,
np.sin(2.0*np.pi*r[1])*B,
np.cos(2.0*np.pi*r[1])*B,
np.sin(2.0*np.pi*r[0])*A])).standardize()
####################################################################################################
# Code below available according to the following conditions on https://github.com/MarDiehl/3Drotations
####################################################################################################
# Copyright (c) 2017-2019, Martin Diehl/Max-Planck-Institut für Eisenforschung GmbH
# Copyright (c) 2013-2014, Marc De Graef/Carnegie Mellon University
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without modification, are
# permitted provided that the following conditions are met:
#
# - Redistributions of source code must retain the above copyright notice, this list
# of conditions and the following disclaimer.
# - Redistributions in binary form must reproduce the above copyright notice, this
# list of conditions and the following disclaimer in the documentation and/or
# other materials provided with the distribution.
# - Neither the names of Marc De Graef, Carnegie Mellon University nor the names
# of its contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
# USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
####################################################################################################
#---------- Quaternion ----------
@staticmethod
def qu2om(qu):
"""Quaternion to rotation matrix."""
qq = qu[0]**2-(qu[1]**2 + qu[2]**2 + qu[3]**2)
om = np.diag(qq + 2.0*np.array([qu[1],qu[2],qu[3]])**2)
om[1,0] = 2.0*(qu[2]*qu[1]+qu[0]*qu[3])
om[0,1] = 2.0*(qu[1]*qu[2]-qu[0]*qu[3])
om[2,1] = 2.0*(qu[3]*qu[2]+qu[0]*qu[1])
om[1,2] = 2.0*(qu[2]*qu[3]-qu[0]*qu[1])
om[0,2] = 2.0*(qu[1]*qu[3]+qu[0]*qu[2])
om[2,0] = 2.0*(qu[3]*qu[1]-qu[0]*qu[2])
return om if P > 0.0 else om.T
@staticmethod
def qu2eu(qu):
"""Quaternion to Bunge-Euler angles."""
q03 = qu[0]**2+qu[3]**2
q12 = qu[1]**2+qu[2]**2
chi = np.sqrt(q03*q12)
if iszero(chi):
eu = np.array([np.arctan2(-P*2.0*qu[0]*qu[3],qu[0]**2-qu[3]**2), 0.0, 0.0]) if iszero(q12) else \
np.array([np.arctan2(2.0*qu[1]*qu[2],qu[1]**2-qu[2]**2), np.pi, 0.0])
else:
eu = np.array([np.arctan2((-P*qu[0]*qu[2]+qu[1]*qu[3])*chi, (-P*qu[0]*qu[1]-qu[2]*qu[3])*chi ),
np.arctan2( 2.0*chi, q03-q12 ),
np.arctan2(( P*qu[0]*qu[2]+qu[1]*qu[3])*chi, (-P*qu[0]*qu[1]+qu[2]*qu[3])*chi )])
# reduce Euler angles to definition range, i.e a lower limit of 0.0
eu = np.where(eu<0, (eu+2.0*np.pi)%np.array([2.0*np.pi,np.pi,2.0*np.pi]),eu)
return eu
@staticmethod
def qu2ax(qu):
"""
Quaternion to axis angle pair.
Modified version of the original formulation, should be numerically more stable
"""
if iszero(qu[1]**2+qu[2]**2+qu[3]**2): # set axis to [001] if the angle is 0/360
ax = [ 0.0, 0.0, 1.0, 0.0 ]
elif not iszero(qu[0]):
s = np.sign(qu[0])/np.sqrt(qu[1]**2+qu[2]**2+qu[3]**2)
omega = 2.0 * np.arccos(np.clip(qu[0],-1.0,1.0))
ax = [ qu[1]*s, qu[2]*s, qu[3]*s, omega ]
else:
ax = [ qu[1], qu[2], qu[3], np.pi]
return np.array(ax)
@staticmethod
def qu2ro(qu):
"""Quaternion to Rodrigues-Frank vector."""
if iszero(qu[0]):
ro = [qu[1], qu[2], qu[3], np.inf]
else:
s = np.linalg.norm([qu[1],qu[2],qu[3]])
ro = [0.0,0.0,P,0.0] if iszero(s) else \
[ qu[1]/s, qu[2]/s, qu[3]/s, np.tan(np.arccos(np.clip(qu[0],-1.0,1.0)))]
return np.array(ro)
@staticmethod
def qu2ho(qu):
"""Quaternion to homochoric vector."""
omega = 2.0 * np.arccos(np.clip(qu[0],-1.0,1.0))
if iszero(omega):
ho = np.array([ 0.0, 0.0, 0.0 ])
else:
ho = np.array([qu[1], qu[2], qu[3]])
f = 0.75 * ( omega - np.sin(omega) )
ho = ho/np.linalg.norm(ho) * f**(1./3.)
return ho
@staticmethod
def qu2cu(qu):
"""Quaternion to cubochoric vector."""
return Rotation.ho2cu(Rotation.qu2ho(qu))
#---------- Rotation matrix ----------
@staticmethod
def om2qu(om):
"""
Rotation matrix to quaternion.
The original formulation (direct conversion) had (numerical?) issues
"""
return Rotation.eu2qu(Rotation.om2eu(om))
@staticmethod
def om2eu(om):
"""Rotation matrix to Bunge-Euler angles."""
if abs(om[2,2]) < 1.0:
zeta = 1.0/np.sqrt(1.0-om[2,2]**2)
eu = np.array([np.arctan2(om[2,0]*zeta,-om[2,1]*zeta),
np.arccos(om[2,2]),
np.arctan2(om[0,2]*zeta, om[1,2]*zeta)])
else:
eu = np.array([np.arctan2( om[0,1],om[0,0]), np.pi*0.5*(1-om[2,2]),0.0]) # following the paper, not the reference implementation
# reduce Euler angles to definition range, i.e a lower limit of 0.0
eu = np.where(eu<0, (eu+2.0*np.pi)%np.array([2.0*np.pi,np.pi,2.0*np.pi]),eu)
return eu
@staticmethod
def om2ax(om):
"""Rotation matrix to axis angle pair."""
ax=np.empty(4)
# first get the rotation angle
t = 0.5*(om.trace() -1.0)
ax[3] = np.arccos(np.clip(t,-1.0,1.0))
if iszero(ax[3]):
ax = [ 0.0, 0.0, 1.0, 0.0]
else:
w,vr = np.linalg.eig(om)
# next, find the eigenvalue (1,0j)
i = np.where(np.isclose(w,1.0+0.0j))[0][0]
ax[0:3] = np.real(vr[0:3,i])
diagDelta = np.array([om[1,2]-om[2,1],om[2,0]-om[0,2],om[0,1]-om[1,0]])
ax[0:3] = np.where(iszero(diagDelta), ax[0:3],np.abs(ax[0:3])*np.sign(-P*diagDelta))
return np.array(ax)
@staticmethod
def om2ro(om):
"""Rotation matrix to Rodrigues-Frank vector."""
return Rotation.eu2ro(Rotation.om2eu(om))
@staticmethod
def om2ho(om):
"""Rotation matrix to homochoric vector."""
return Rotation.ax2ho(Rotation.om2ax(om))
@staticmethod
def om2cu(om):
"""Rotation matrix to cubochoric vector."""
return Rotation.ho2cu(Rotation.om2ho(om))
#---------- Bunge-Euler angles ----------
@staticmethod
def eu2qu(eu):
"""Bunge-Euler angles to quaternion."""
ee = 0.5*eu
cPhi = np.cos(ee[1])
sPhi = np.sin(ee[1])
qu = np.array([ cPhi*np.cos(ee[0]+ee[2]),
-P*sPhi*np.cos(ee[0]-ee[2]),
-P*sPhi*np.sin(ee[0]-ee[2]),
-P*cPhi*np.sin(ee[0]+ee[2]) ])
if qu[0] < 0.0: qu*=-1
return qu
@staticmethod
def eu2om(eu):
"""Bunge-Euler angles to rotation matrix."""
c = np.cos(eu)
s = np.sin(eu)
om = np.array([[+c[0]*c[2]-s[0]*s[2]*c[1], +s[0]*c[2]+c[0]*s[2]*c[1], +s[2]*s[1]],
[-c[0]*s[2]-s[0]*c[2]*c[1], -s[0]*s[2]+c[0]*c[2]*c[1], +c[2]*s[1]],
[+s[0]*s[1], -c[0]*s[1], +c[1] ]])
om[np.where(iszero(om))] = 0.0
return om
@staticmethod
def eu2ax(eu):
"""Bunge-Euler angles to axis angle pair."""
t = np.tan(eu[1]*0.5)
sigma = 0.5*(eu[0]+eu[2])
delta = 0.5*(eu[0]-eu[2])
tau = np.linalg.norm([t,np.sin(sigma)])
alpha = np.pi if iszero(np.cos(sigma)) else \
2.0*np.arctan(tau/np.cos(sigma))
if iszero(alpha):
ax = np.array([ 0.0, 0.0, 1.0, 0.0 ])
else:
ax = -P/tau * np.array([ t*np.cos(delta), t*np.sin(delta), np.sin(sigma) ]) # passive axis angle pair so a minus sign in front
ax = np.append(ax,alpha)
if alpha < 0.0: ax *= -1.0 # ensure alpha is positive
return ax
@staticmethod
def eu2ro(eu):
"""Bunge-Euler angles to Rodrigues-Frank vector."""
ro = Rotation.eu2ax(eu) # convert to axis angle pair representation
if ro[3] >= np.pi: # Differs from original implementation. check convention 5
ro[3] = np.inf
elif iszero(ro[3]):
ro = np.array([ 0.0, 0.0, P, 0.0 ])
else:
ro[3] = np.tan(ro[3]*0.5)
return ro
@staticmethod
def eu2ho(eu):
"""Bunge-Euler angles to homochoric vector."""
return Rotation.ax2ho(Rotation.eu2ax(eu))
@staticmethod
def eu2cu(eu):
"""Bunge-Euler angles to cubochoric vector."""
return Rotation.ho2cu(Rotation.eu2ho(eu))
#---------- Axis angle pair ----------
@staticmethod
def ax2qu(ax):
"""Axis angle pair to quaternion."""
if iszero(ax[3]):
qu = np.array([ 1.0, 0.0, 0.0, 0.0 ])
else:
c = np.cos(ax[3]*0.5)
s = np.sin(ax[3]*0.5)
qu = np.array([ c, ax[0]*s, ax[1]*s, ax[2]*s ])
return qu
@staticmethod
def ax2om(ax):
"""Axis angle pair to rotation matrix."""
c = np.cos(ax[3])
s = np.sin(ax[3])
omc = 1.0-c
om=np.diag(ax[0:3]**2*omc + c)
for idx in [[0,1,2],[1,2,0],[2,0,1]]:
q = omc*ax[idx[0]] * ax[idx[1]]
om[idx[0],idx[1]] = q + s*ax[idx[2]]
om[idx[1],idx[0]] = q - s*ax[idx[2]]
return om if P < 0.0 else om.T
@staticmethod
def ax2eu(ax):
"""Rotation matrix to Bunge Euler angles."""
return Rotation.om2eu(Rotation.ax2om(ax))
@staticmethod
def ax2ro(ax):
"""Axis angle pair to Rodrigues-Frank vector."""
if iszero(ax[3]):
ro = [ 0.0, 0.0, P, 0.0 ]
else:
ro = [ax[0], ax[1], ax[2]]
# 180 degree case
ro += [np.inf] if np.isclose(ax[3],np.pi,atol=1.0e-15,rtol=0.0) else \
[np.tan(ax[3]*0.5)]
return np.array(ro)
@staticmethod
def ax2ho(ax):
"""Axis angle pair to homochoric vector."""
f = (0.75 * ( ax[3] - np.sin(ax[3]) ))**(1.0/3.0)
ho = ax[0:3] * f
return ho
@staticmethod
def ax2cu(ax):
"""Axis angle pair to cubochoric vector."""
return Rotation.ho2cu(Rotation.ax2ho(ax))
#---------- Rodrigues-Frank vector ----------
@staticmethod
def ro2qu(ro):
"""Rodrigues-Frank vector to quaternion."""
return Rotation.ax2qu(Rotation.ro2ax(ro))
@staticmethod
def ro2om(ro):
"""Rodgrigues-Frank vector to rotation matrix."""
return Rotation.ax2om(Rotation.ro2ax(ro))
@staticmethod
def ro2eu(ro):
"""Rodrigues-Frank vector to Bunge-Euler angles."""
return Rotation.om2eu(Rotation.ro2om(ro))
@staticmethod
def ro2ax(ro):
"""Rodrigues-Frank vector to axis angle pair."""
ta = ro[3]
if iszero(ta):
ax = [ 0.0, 0.0, 1.0, 0.0 ]
elif not np.isfinite(ta):
ax = [ ro[0], ro[1], ro[2], np.pi ]
else:
angle = 2.0*np.arctan(ta)
ta = 1.0/np.linalg.norm(ro[0:3])
ax = [ ro[0]/ta, ro[1]/ta, ro[2]/ta, angle ]
return np.array(ax)
@staticmethod
def ro2ho(ro):
"""Rodrigues-Frank vector to homochoric vector."""
if iszero(np.sum(ro[0:3]**2.0)):
ho = [ 0.0, 0.0, 0.0 ]
else:
f = 2.0*np.arctan(ro[3]) -np.sin(2.0*np.arctan(ro[3])) if np.isfinite(ro[3]) else np.pi
ho = ro[0:3] * (0.75*f)**(1.0/3.0)
return np.array(ho)
@staticmethod
def ro2cu(ro):
"""Rodrigues-Frank vector to cubochoric vector."""
return Rotation.ho2cu(Rotation.ro2ho(ro))
#---------- Homochoric vector----------
@staticmethod
def ho2qu(ho):
"""Homochoric vector to quaternion."""
return Rotation.ax2qu(Rotation.ho2ax(ho))
@staticmethod
def ho2om(ho):
"""Homochoric vector to rotation matrix."""
return Rotation.ax2om(Rotation.ho2ax(ho))
@staticmethod
def ho2eu(ho):
"""Homochoric vector to Bunge-Euler angles."""
return Rotation.ax2eu(Rotation.ho2ax(ho))
@staticmethod
def ho2ax(ho):
"""Homochoric vector to axis angle pair."""
tfit = np.array([+1.0000000000018852, -0.5000000002194847,
-0.024999992127593126, -0.003928701544781374,
-0.0008152701535450438, -0.0002009500426119712,
-0.00002397986776071756, -0.00008202868926605841,
+0.00012448715042090092, -0.0001749114214822577,
+0.0001703481934140054, -0.00012062065004116828,
+0.000059719705868660826, -0.00001980756723965647,
+0.000003953714684212874, -0.00000036555001439719544])
# normalize h and store the magnitude
hmag_squared = np.sum(ho**2.)
if iszero(hmag_squared):
ax = np.array([ 0.0, 0.0, 1.0, 0.0 ])
else:
hm = hmag_squared
# convert the magnitude to the rotation angle
s = tfit[0] + tfit[1] * hmag_squared
for i in range(2,16):
hm *= hmag_squared
s += tfit[i] * hm
ax = np.append(ho/np.sqrt(hmag_squared),2.0*np.arccos(np.clip(s,-1.0,1.0)))
return ax
@staticmethod
def ho2ro(ho):
"""Axis angle pair to Rodrigues-Frank vector."""
return Rotation.ax2ro(Rotation.ho2ax(ho))
@staticmethod
def ho2cu(ho):
"""Homochoric vector to cubochoric vector."""
return Lambert.BallToCube(ho)
#---------- Cubochoric ----------
@staticmethod
def cu2qu(cu):
"""Cubochoric vector to quaternion."""
return Rotation.ho2qu(Rotation.cu2ho(cu))
@staticmethod
def cu2om(cu):
"""Cubochoric vector to rotation matrix."""
return Rotation.ho2om(Rotation.cu2ho(cu))
@staticmethod
def cu2eu(cu):
"""Cubochoric vector to Bunge-Euler angles."""
return Rotation.ho2eu(Rotation.cu2ho(cu))
@staticmethod
def cu2ax(cu):
"""Cubochoric vector to axis angle pair."""
return Rotation.ho2ax(Rotation.cu2ho(cu))
@staticmethod
def cu2ro(cu):
"""Cubochoric vector to Rodrigues-Frank vector."""
return Rotation.ho2ro(Rotation.cu2ho(cu))
@staticmethod
def cu2ho(cu):
"""Cubochoric vector to homochoric vector."""
return Lambert.CubeToBall(cu)