Adds the to_rotation_translation function to the dual_quaternion module.

tensorflow_graphics/geometry/transformation/dual_quaternion.py

@@ -33,6 +33,8 @@
 from __future__ import division
 from __future__ import print_function
 
+from typing import Tuple
+
 import tensorflow as tf
 from tensorflow_graphics.geometry.transformation import quaternion
 from tensorflow_graphics.math import vector
@@ -271,7 +273,7 @@ def from_rotation_translation(
 
   Returns:
     A `[A1, ..., An, 8]`-tensor, where the last dimension represents a
-    normalized quaternion.
+    normalized dual quaternion.
 
   Raises:
     ValueError: If the shape of `rotation_matrix` is not supported.
@@ -304,5 +306,35 @@ def from_rotation_translation(
     return tf.concat((quaternion_rotation, dual_quaternion_dual_part), axis=-1)
 
 
+def to_rotation_translation(
+    dual_quaternion: type_alias.TensorLike,
+    name: str = "dual_quaternion_to_rot_trans") -> Tuple[tf.Tensor, tf.Tensor]:
+  """Converts a dual quaternion into a quaternion for rotation and translation.
+
+  Args:
+    dual_quaternion: A `[A1, ..., An, 8]`-tensor, where the last dimension
+      represents a qual quaternion.
+    name: A name for this op that defaults to "dual_quaternion_to_rot_trans".
+
+  Returns:
+    A `[A1, ..., An, 7]`-tensor, where the last dimension represents a
+    normalized quaternion and a translation vector, in that order.
+  """
+  with tf.name_scope(name):
+    dual_quaternion = tf.convert_to_tensor(value=dual_quaternion)
+
+    shape.check_static(
+        tensor=dual_quaternion,
+        tensor_name="dual_quaternion",
+        has_dim_equals=(-1, 8))
+
+    rotation = dual_quaternion[..., 0:4]
+    translation = 2 * quaternion.multiply(
+        dual_quaternion[..., 4:8], quaternion.inverse(rotation))
+    translation = translation[..., 0:3]
+
+    return rotation, translation
+
+
 # API contains all public functions and classes.
 __all__ = export_api.get_functions_and_classes()

tensorflow_graphics/geometry/transformation/tests/dual_quaternion_test.py

@@ -15,6 +15,7 @@
 
 from absl.testing import flagsaver
 from absl.testing import parameterized
+
 import numpy as np
 import tensorflow as tf
 
@@ -265,5 +266,43 @@ def test_from_rotation_matrix_random(self):
     self.assertAllClose(rotation_gt, rotation)
     self.assertAllClose(translation_gt, translation)
 
+  @flagsaver.flagsaver(tfg_add_asserts_to_graph=False)
+  def test_to_rotation_translation_jacobian_preset(self):
+    pre_dual_quaternion = test_helpers.generate_preset_test_dual_quaternions()
+
+    def to_rotation(input_dual_quaternion):
+      rotation, _ = dual_quaternion.to_rotation_translation(
+          input_dual_quaternion)
+      return rotation
+
+    self.assert_jacobian_is_finite_fn(to_rotation, [pre_dual_quaternion])
+
+  @flagsaver.flagsaver(tfg_add_asserts_to_graph=False)
+  def test_to_rotation_translation_jacobian_random(self):
+    rnd_dual_quaternion = test_helpers.generate_random_test_dual_quaternions()
+
+    def to_translation(input_dual_quaternion):
+      _, translation = dual_quaternion.to_rotation_translation(
+          input_dual_quaternion)
+      return translation
+
+    self.assert_jacobian_is_finite_fn(to_translation, [rnd_dual_quaternion])
+
+  def test_to_rotation_matrix_random(self):
+    (euler_angles_gt, translation_gt
+    ) = test_helpers.generate_random_test_euler_angles_translations()
+    rotation_gt = rotation_matrix_3d.from_quaternion(
+        quaternion.from_euler(euler_angles_gt))
+
+    dual_quaternion_output = dual_quaternion.from_rotation_translation(
+        rotation_gt, translation_gt)
+    rotation, translation = dual_quaternion.to_rotation_translation(
+        dual_quaternion_output)
+
+    self.assertAllClose(rotation_gt,
+                        rotation_matrix_3d.from_quaternion(rotation))
+    self.assertAllClose(translation_gt, translation)
+
+
 if __name__ == "__main__":
   test_case.main()