paralleldomain.utilities.transformation

class Transformation(quaternion=None, translation=None)

Multi-purpose 6DoF object.

When printed, the rotation is given as euler angles in degrees following intrinsic rotation order XYZ, rounded to 2 decimal places.

Parameters:

  • quaternion (Union[Quaternion, List[float], ndarray, None]) – Quaternion instance or elements for rotation. Elements are expected in order (w,x,y,z). Default: Unit quaternion without rotation.

  • translation (Union[ndarray, List, None]) – List-like translation information in order (x,y,z). Default: [0,0,0]

Example

Transformation instances can be easily matrix-multiplied with other Transformation instances or any np.ndarray of shape (4,n).

lidar_frame = ...  # get any `SensorFrame` from a LiDAR sensor
points_vehicle_frame = (lidar_frame.extrinsic @ lidar_frame.xyz_one.T).T
points_world_frame = (lidar_frame.pose @ lidar_frame.xyz_one.T).T

boxes_3d = lidar_frame.get_annotations(AnnotationTypes.BoundingBoxes3D)

for b in boxes_3d.boxes:
    box_pose_world_frame = lidar_frame.pose @ b.pose
as_euler_angles(order, degrees=False)

Returns the rotation of a Transformation object as euler angles.

Parameters:

  • order (str) – Defines the axes rotation order. Use lower case for extrinsic rotation, upper case for intrinsic rotation. Ex: xyz, ZYX, xzx.

  • degrees (bool) – Defines if euler angles should be returned in degrees instead of radians. Default: False

Return type:

ndarray

Returns:

Ordered array of euler angles with length 3.

classmethod from_euler_angles(angles, order, translation=None, degrees=False)

Creates a transformation object from euler angles and optionally translation (default: (0,0,0))

Parameters:

  • angles (Union[ndarray, List[float]]) – Ordered euler angles array with length 3

  • translation (Union[ndarray, List[float], None]) – Translation vector in order (x,y,z). Default: [0,0,0]

  • order (str) – Defines the axes rotation order. Use lower case for extrinsic rotation, upper case for intrinsic rotation. Ex: xyz, ZYX, xzx.

  • degrees (bool) – Defines if euler angles are provided in degrees instead of radians. Default: False

Return type:

Transformation

Returns:

Instance of Transformation with provided parameters.

classmethod from_transformation_matrix(mat, approximate_orthogonal=False)

Creates a Transformation object from an homogeneous transformation matrix of shape (4,4)

Parameters:

  • mat (ndarray) – Transformation matrix as described in transformation_matrix

  • approximate_orthogonal (bool) – When set to True, non-orthogonal matrices will be approximate to their closest orthogonal representation. Default: False.

Return type:

Transformation

Returns:

Instance of Transformation with provided parameters.

classmethod interpolate(tf0, tf1, factor=0.5)

Interpolates the translation and rotation between two Transformation objects.

For translation, linear interpolation is used:

tf0.translation + factor * (tf1.translation - tf0.translation). For rotation, spherical linear interpolation of rotation quaternions is used: tf0.quaternion * (conjugate(tf0.quaternion) * tf1.quaternion)**factor

Parameters:

  • tf0 (Transformation) – First Transformation object used as interpolation start

  • tf1 (Transformation) – Second Transformation object used as interpolation end

  • factor (float) – Interpolation factor within [0.0, 1.0]. If 0.0, the return value is equal to tf0; if 1.0, the return value is equal to tf1. Values smaller than 0.0 or greater than 1.0 can be used if extrapolation is desired. Default: 0.5

Return type:

Transformation

Returns:

A new Transformation object that is at the interpolated factor between tf0 and tf1.

static look_at(target, coordinate_system, position=None)

Calculates the pose transformation of being located at the given positions and looking at the given target. :type target: Union[ndarray, List[float]] :param target: The position to look at :type coordinate_system: str :param coordinate_system: The coordinate system the result, target and position are in :type position: Union[ndarray, List[float], None] :param position: the position to look from

Return type:

Transformation

Returns:

Instance of Transformation looking from position to target

Parameters:

  • target (ndarray | List[float]) –

  • coordinate_system (str) –

  • position (ndarray | List[float] | None) –

property inverse: Transformation

Returns the inverse transformation as a new Transformation object.

property quaternion: Quaternion

Returns the rotation as a pyquaternion.quaternion.Quaternion instance.

Full documentation can be found in pyquaternion API Documentation.

To get the quaternion coefficients, either call .elements, iterate over the object itself or use the dedicated named properties. The element order (until explicitly stated otherwise) should always be assumed as (w,x,y,z) for function w + xi+ yj + zk

from paralleldomain.model.transformation import Transformation

tf = Transformation.from_euler_angles(yaw=90, pitch=0, roll=0, is_degrees=True)

assert(tf.quaternion.elements[0] == tf.quaternion[0] == tf.quaternion.w)
assert(tf.quaternion.elements[1] == tf.quaternion[1] == tf.quaternion.x)
assert(tf.quaternion.elements[2] == tf.quaternion[2] == tf.quaternion.y)
assert(tf.quaternion.elements[3] == tf.quaternion[3] == tf.quaternion.z)

Please note that when using scipy.spatial.transform.Rotation, scipy assumes the order as (x,y,w,z).

from paralleldomain.model.transformation import Transformation
from scipy.spatial.transform import Rotation
import numpy as np

tf = Transformation.from_euler_angles(yaw=90, pitch=0, roll=0, is_degrees=True)
tf_scipy = Rotation.from_quat([
    tf.quaternion.x,
    tf.quaternion.y,
    tf.quaternion.z,
    tf.quaternion.w
])

# Check that rotation quaternion is equal within tolerance
np.allclose(tf.rotation == tf_scipy.as_matrix())  # returns True
property rotation: ndarray

Returns the rotation matrix in shape (3,3).

/              \
|R_11 R_12 R_13|
|R_21 R_22 R_23|
|R_31 R_32 R_33|
\              /
property transformation_matrix: ndarray

Returns the homogeneous transformation matrix in shape (4,4).

/                  \
|R_11 R_12 R_13 t_x|
|R_21 R_22 R_23 t_y|
|R_31 R_32 R_33 t_z|
|0    0    0    1  |
\                  /
property translation: ndarray

Returns the translation vector (x,y,z) in shape (3,).