Create transformations.py

transformations.py

@@ -0,0 +1,44 @@
+
+def get_translation_t(t):
+    """Get the translation matrix for movement in t."""
+    matrix = [
+        [1, 0, 0, 0],
+        [0, 1, 0, 0],
+        [0, 0, 1, t],
+        [0, 0, 0, 1],
+    ]
+    return tf.convert_to_tensor(matrix, dtype=tf.float32)
+
+
+def get_rotation_phi(phi):
+    """Get the rotation matrix for movement in phi."""
+    matrix = [
+        [1, 0, 0, 0],
+        [0, tf.cos(phi), -tf.sin(phi), 0],
+        [0, tf.sin(phi), tf.cos(phi), 0],
+        [0, 0, 0, 1],
+    ]
+    return tf.convert_to_tensor(matrix, dtype=tf.float32)
+
+
+def get_rotation_theta(theta):
+    """Get the rotation matrix for movement in theta."""
+    matrix = [
+        [tf.cos(theta), 0, -tf.sin(theta), 0],
+        [0, 1, 0, 0],
+        [tf.sin(theta), 0, tf.cos(theta), 0],
+        [0, 0, 0, 1],
+    ]
+    return tf.convert_to_tensor(matrix, dtype=tf.float32)
+
+
+def pose_spherical(theta, phi, t):
+    """
+    Get the camera to world matrix for the corresponding theta, phi
+    and t.
+    """
+    c2w = get_translation_t(t)
+    c2w = get_rotation_phi(phi / 180.0 * np.pi) @ c2w
+    c2w = get_rotation_theta(theta / 180.0 * np.pi) @ c2w
+    c2w = np.array([[-1, 0, 0, 0], [0, 0, 1, 0], [0, 1, 0, 0], [0, 0, 0, 1]]) @ c2w
+    return c2w