Document Human Hand wrist coordinate frame

Document the released aligned Human Hand wrist axes and add a public-validation projection example.

.gitattributes

@@ -58,3 +58,7 @@ saved_model/**/* filter=lfs diff=lfs merge=lfs -text
 # Video files - compressed
 *.mp4 filter=lfs diff=lfs merge=lfs -text
 *.webm filter=lfs diff=lfs merge=lfs -text
+
+# Keep the small README coordinate-frame illustration in regular Git so that
+# it renders directly on the dataset card without requiring an LFS checkout.
+assets/human_hand_wrist_coordinate_frame.png -filter -diff -merge

README.md

@@ -4,9 +4,9 @@ pretty_name: WorldOracle Validation Ground Truth
 
 # WorldOracle Validation Ground Truth
 
-This private dataset contains the frozen validation split and its ground-truth
-data for WorldOracle. It must remain private until the benchmark release and
-data-access policy have been approved.
+This public dataset contains the frozen WorldOracle validation split and its
+ground-truth data. It contains validation episodes only and does not include
+test-set ground truth.
 
 The data is stored as one uncompressed tar archive per episode. This keeps the
 repository resumable and avoids hundreds of thousands of individual Hub files.
@@ -24,7 +24,53 @@ Extract an episode with `tar -xf <episode>.tar -C <destination>`.
 
 `validation_manifest.json` is the canonical inventory. It records the path,
 size and SHA-256 of every episode archive. `SHA256SUMS` covers all repository
-files except itself.
+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.
 
 ## License and Citation
 
@@ -36,4 +82,4 @@ All data in this repository are licensed under [**CC BY-NC-SA 4.0**](https://cre
   author={Duan, Haoyi and Chen, Liliang and Wang, Nan and Zhang, Yang and Lu, Yuhang and Chen, Xiaotong and Tseng, Wei-Cheng and Gao, Shenyuan and Li, Zhaoshuo and Jin, Jingyi and others},
   journal={arXiv preprint arXiv:2610.18826},
   year={2026}
-}
+}