Update validation metadata: README.md

README.md

@@ -26,51 +26,26 @@ Extract an episode with `tar -xf <episode>.tar -C <destination>`.
 size and SHA-256 of every episode archive. `SHA256SUMS` covers all repository
 files except itself. Validation inputs are available under `inputs/`.
 
-## Human Hand wrist-local coordinate frame
-
-Human Hand inputs use a 57-dimensional action vector containing camera motion,
-right-wrist motion, five right fingertips, left-wrist motion, and five left
-fingertips. Fingertip positions are expressed in the corresponding released
-wrist-local frame.
-
-The released frame is obtained from the source wrist pose by applying the
-following fixed alignment:
-
-```text
-aligned_wrist_in_camera = source_wrist_in_camera @ A
-
-    [ 0  1  0  0 ]
-A = [-1  0  0  0 ]
-    [ 0  0  1  0 ]
-    [ 0  0  0  1 ]
-```
-
-Consequently, the axes of the **released, aligned frame** are defined as:
-
-- **+X (red):** normal to the palm plane, pointing from the dorsal side toward
-  the palmar side.
-- **+Y (green):** from wrist to fingertips for the left hand, and from
-  fingertips to wrist for the right hand.
-- **+Z (blue):** within the palm plane, pointing from the pinky side toward the
-  thumb side.
-
-The illustration below projects these released axes onto a public validation
-frame. `L` and `R` mark the left- and right-wrist origins, respectively.
-
-![Released Human Hand wrist-local coordinate frame](assets/human_hand_wrist_coordinate_frame.png)
-
-For a fingertip position given in the head-camera frame, the released
-wrist-local coordinate is computed as:
-
-```text
-fingertip_in_wrist = inverse(aligned_wrist_in_camera) @ fingertip_in_camera
-```
-
-The raw source-frame joint positions and `xyzw` quaternions are retained in
-`controls/hand_camera_poses.npz`. The machine-readable 57D field layout is
-provided in each episode's `controls/action_57d_spec.json`. The source wrist
-basis and the released aligned basis are therefore intentionally not
-interchangeable.
+## Human Hand absolute pose format
+
+Human Hand validation inputs provide synchronized absolute hand and camera
+poses in `controls/hand_camera_poses.npz`. Pose sample `t` corresponds directly
+to validation video frame `t`.
+
+- `left_positions_camera` and `right_positions_camera` contain the 21 hand
+  joints in the released camera-reference coordinates.
+- `left_quaternions_camera_xyzw` and `right_quaternions_camera_xyzw` contain
+  the corresponding joint orientations in XYZW order.
+- `camera_position_world` and `camera_quaternion_world_xyzw` contain the
+  tracked camera-reference pose.
+- `left_valid`, `right_valid`, and `camera_valid` indicate whether each
+  measurement is usable.
+
+The leading initialization interval in which the pose tracking was invalid has
+been removed, so the first released sample is valid. Any unavailable
+measurements occurring later in an episode remain present and are marked by
+the validity arrays. Delta-action tensors, source-frame indices, internal
+source mappings, and cleaning records are not part of the public release.
 
 ## Human Hand joint visualization