py3dframe.Frame.get_global_quaternion#

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

Access the quaternion representation of the rotation between the global frame and this frame in the given 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 global_quaternion to get or set the quaternion between the global frame and this frame in the convention of the frame.

  • method set_global_quaternion() to set the quaternion between the global frame and this frame in a specific convention.

  • method get_quaternion() to get the quaternion between the parent frame and this frame in a specific convention.

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.

Returns:

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

Return type:

numpy.ndarray

Examples

Lets consider a train and a person standing into the train.

First we can define the train frame relative to the global frame (the canonical frame) and then we can define the person frame relative to the train frame.

from py3dframe import Frame

train = Frame.from_axes(origin=[0, 0, 0], x_axis=[1, 0, 0], y_axis=[0, 1, 0], z_axis=[0, 0, 1], parent=None)
person = Frame.from_axes(origin=[0, 1, 0], x_axis=[1, 0, 0], y_axis=[0, 1, 0], z_axis=[0, 0, 1], parent=train)

Lets assume the train moves and the person moves inside the train.

train.set_translation([10, 0, 0], convention=0) # The train moves of 10 units along the x axis of the global frame.

person.set_translation([0, 2, 0], convention=0) # The person moves by 1 unit along the y axis of the train frame.
person.set_euler_angles([0, 0, 45], convention=0, degrees=True) # The person rotates of 45 degrees around the z axis of the train frame.

If an application using an other convention required the quaternion between the global frame and the person frame in the convention 4 and scalar first convention, you can access this quaternion with the get_global_quaternion() method:

global_quaternion_person = person.get_global_quaternion(convention=4, scalar_first=True) # Get the quaternion between the global frame and the person frame in convention 4 in the scalar first convention.