py3dframe.Frame.get_quaternion#

Frame.get_quaternion(*, convention=None, scalar_first=True)[source]#

Access the quaternion representation of the rotation between the parent frame and this frame in a specific convention.

The quaternion is returned as a numpy array with shape (4,) in the scalar first [w, x, y, z] or scalar last [x, y, z, w] convention.

See also

  • attribute parent to get or set the parent frame.

  • attribute convention to get or set the convention of the frame.

  • attribute quaternion to get or set the quaternion in the convention of the frame.

  • method set_quaternion() to set the quaternion in a specific convention.

  • method get_global_quaternion() to get the quaternion between the global frame and this frame.

Parameters:

  • convention (Optional[int], optional) – Integer in [0, 7] selecting the convention. Defaults to the frame’s own convention.

  • scalar_first (bool, optional) – If True, the quaternion is in the scalar first convention. Default is True. If False, the quaternion is in the scalar last convention.

Returns:

The quaternion between the parent frame and this frame in the given convention with shape (4,).

Return type:

numpy.ndarray

Examples

Lets create a frame from its axes and origin with the default convention 0.

import numpy
from py3dframe import Frame

origin = numpy.array([-1, -2, -3])
x_axis = numpy.array([1, 1, 0]) / numpy.sqrt(2)
y_axis = numpy.array([-1, 1, 0]) / numpy.sqrt(2)
z_axis = numpy.array([0, 0, 1])

parent = ... # Define the parent frame if needed, otherwise parent=None to use the canonical frame.

frame = Frame.from_axes(origin=origin, x_axis=x_axis, y_axis=y_axis, z_axis=z_axis, convention=0, parent=parent)

If an application using an other convention required the quaternion in the convention 4 with scalar first convention, you can access the quaternion in this convention with the get_quaternion() method.

quaternion_convention_4 = frame.get_quaternion(convention=4, scalar_first=True)
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