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Human Ego Hand Trajectory Dataset
Overview
This package contains synchronized egocentric manipulation episodes recorded by six cameras. Each episode provides:
- six upright camera videos at 1920 x 1080 and 30 FPS;
- frame-aligned 2D hand observations from all six camera views;
- metric 21-joint 3D hand trajectories in one shared camera reference frame;
- bilingual dense action annotations with temporal segments;
- a synchronized trajectory review video and semantic timeline page.
This sample contains 8 episodes. Using hand-frames with available 2D hand observations as the denominator, the overall 3D hand-trajectory coverage is 98.7% (6090 / 6170), and every episode exceeds 98% coverage. The trajectories can be projected into each original camera view using the provided six-camera calibration. In views where the hand is visible, the projected skeleton remains consistently aligned with the corresponding hand. Exact per-episode coverage values are listed in meta/episode_index.csv.
Review Overlay Provenance
For every hand-frame represented in hand_pose/trajectory_3d.parquet, the corresponding skeleton in review/review.mp4 is generated by projecting the delivered metric 3D trajectory through the six-camera calibration. It is not a direct rendering of hand_pose/observations_2d.parquet.
For the small number of hand-frames without a 3D row, the review video may use an auxiliary 2D observation only to preserve visual continuity. Such a fallback overlay is not part of trajectory_3d.parquet and must not be interpreted as a delivered 3D trajectory. Numerical use should treat trajectory_3d.parquet, coordinate_system.json, and calibration/headset_02_1080p.json as authoritative.
Key Highlights
- High 3D coverage: 98.7% overall, with per-episode coverage ranging from 98.01% to 99.81%.
- Unified six-camera geometry: all 3D trajectories use one metric
mid_cam_leftreference frame. - Reproducible projection: complete intrinsics, distortion parameters, and reference-camera extrinsics are provided for all six cameras.
- Complete time alignment: videos, 2D observations, 3D trajectories, and semantic segments share one 30 FPS timeline.
Per-Episode 3D Trajectory Coverage
Coverage is calculated as hand-frames with an available 3D trajectory divided by hand-frames with an available 2D hand observation.
| Episode | Video frames | Frames with both hands in 3D | Frames with one hand in 3D | 3D trajectory hand-frames | Observed 2D hand-frames | Coverage |
|---|---|---|---|---|---|---|
episode_000001 |
228 | 182 | 46 | 410 | 416 | 98.56% |
episode_000002 |
228 | 226 | 2 | 454 | 455 | 99.78% |
episode_000003 |
255 | 248 | 7 | 503 | 509 | 98.82% |
episode_000004 |
303 | 289 | 14 | 592 | 604 | 98.01% |
episode_000005 |
525 | 519 | 6 | 1044 | 1046 | 99.81% |
episode_000006 |
165 | 123 | 42 | 288 | 293 | 98.29% |
episode_000007 |
825 | 774 | 51 | 1599 | 1630 | 98.10% |
episode_000008 |
612 | 588 | 24 | 1200 | 1217 | 98.60% |
| Total | 3141 | 2949 | 192 | 6090 | 6170 | 98.70% |
Directory Layout
tasks/
task_NNNN__english_task_name/
episode_NNNN__episode_NNNNNN/
episode_manifest.json
videos/
left_cam_left.mp4
left_cam_right.mp4
mid_cam_left.mp4
mid_cam_right.mp4
right_cam_left.mp4
right_cam_right.mp4
hand_pose/
observations_2d.parquet
trajectory_3d.parquet
coordinate_system.json
semantic/
annotation.json
timestamps/
episode_timebase.json
review/
review.mp4
annotation.html
calibration/
headset_02_1080p.json
meta/
episode_index.csv
task_summary.csv
delivery_summary.json
index.html
Open meta/index.html in a browser to browse all episodes. Each episode also contains a standalone review/annotation.html page. All links are package-relative and remain valid after moving the complete dataset directory.
3D Hand Trajectory
Each row in hand_pose/trajectory_3d.parquet represents one hand in one video frame. A row is written only when a 3D trajectory is available; missing trajectories are not represented by NaN rows. Every public keypoints_3d value is finite and has shape 21 x 3.
The two hands are distinguished by the hand field, so one frame can contain up to two rows: left and right. The 8 episodes contain 3,141 video frames in total. All 3,141 frames contain 3D data for at least one hand; 2,949 frames contain 3D data for both hands, and 192 frames contain 3D data for one hand. No coordinates are fabricated for a hand that is outside the view or lacks an available 3D result, and no NaN placeholder row is written. Use (frame_index, hand) as the composite key when constructing a frame-major bimanual tensor.
Missing-hand semantics are defined as follows:
- A
hand == "left"row means that a left-hand 3D trajectory is available for that frame; the same rule applies toright. - If a frame has no
leftrow, no usable left-hand 3D trajectory is available for that frame. It must not be interpreted as a zero vector or as the coordinate origin. - If
observations_2d.parquetstill contains a left-hand observation at that frame, the frame has 2D evidence but no available 3D trajectory. If no camera contains a left-hand 2D observation, the left hand is generally absent, outside the field of view, or fully invisible. - The package contains 2,995 left-hand 3D rows and 3,095 right-hand 3D rows, for a total of 6,090 hand-frames.
| Field | Description |
|---|---|
frame_index |
Zero-based episode video frame index. |
timestamp_s |
Time in seconds relative to the episode start. |
hand |
left or right. |
keypoints_3d |
21 x 3 metric hand-joint coordinates. |
reference_camera |
Always mid_cam_left in this package. |
coordinate_units |
Always meters in this package. |
The 3D coordinates use the upright mid_cam_left optical frame:
- +X points to image right;
- +Y points to image down;
- +Z points forward from the camera.
The exact 21-joint order and axis definitions are stored in hand_pose/coordinate_system.json.
21-Joint Index Mapping
The left and right hands use the same index definition and are distinguished by the per-row hand field.
| Index | Joint name |
|---|---|
| 0 | wrist |
| 1 | thumb_cmc |
| 2 | thumb_mcp |
| 3 | thumb_ip |
| 4 | thumb_tip |
| 5 | index_mcp |
| 6 | index_pip |
| 7 | index_dip |
| 8 | index_tip |
| 9 | middle_mcp |
| 10 | middle_pip |
| 11 | middle_dip |
| 12 | middle_tip |
| 13 | ring_mcp |
| 14 | ring_pip |
| 15 | ring_dip |
| 16 | ring_tip |
| 17 | pinky_mcp |
| 18 | pinky_pip |
| 19 | pinky_dip |
| 20 | pinky_tip |
2D Hand Observations
hand_pose/observations_2d.parquet contains frame-aligned 2D observations from the six camera views.
| Field | Description |
|---|---|
frame_index |
Zero-based episode frame index. |
timestamp_s |
Time in seconds relative to the episode start. |
camera |
Camera name matching a file under videos/. |
hand |
left or right. |
keypoints_2d |
21 x 2 pixel coordinates in the upright 1920 x 1080 image. |
confidence |
Relative observation-level confidence score; not a calibrated probability. |
observations_2d follows this exact contract with the delivered camera videos:
- For a row with
camera == "mid_cam_left",keypoints_2dis expressed directly in the pixel plane ofvideos/mid_cam_left.mp4in the same episode. The same rule applies to every other camera. - Each delivered camera video is 1920 x 1080. Coordinates are measured in pixels using the OpenCV image convention: the center of the top-left pixel is
(0, 0), +X points right, and +Y points down. Coordinates are not normalized to[0, 1]. - Each raw 3840 x 1080 stereo frame is split into two 1920 x 1080 camera views and then rotated by 180 degrees to produce the delivered upright videos. The 2D keypoints are generated in this delivered pixel plane. No additional resize, crop, or rotation is applied relative to the delivered MP4 files.
- Both the videos and 2D coordinates remain in the distorted camera pixel plane; they are not undistorted. Use
distortion_coefficientsfrom the calibration file when projecting 3D points into a video. frame_indexis zero-based.frame_index = imaps exactly to decoded frameiofvideos/{camera}.mp4, andtimestamp_s = i / 30. All six videos start at 0 seconds and contain the same number of frames.- Coordinates are not clamped to the image boundary. When a hand is only partially visible near an image edge, some semantic joints may lie outside
[0, 1920) x [0, 1080); users can derive a per-jointin_framemask from these bounds.
Camera Calibration
calibration/headset_02_1080p.json contains the intrinsics, OpenCV radial-tangential distortion coefficients, image dimensions, and reference-camera extrinsics for all six cameras.
For a 3D point p_ref from trajectory_3d.parquet, the transform convention is:
p_camera_h = T_reference_to_camera[camera] @ [p_ref.x, p_ref.y, p_ref.z, 1]
Project p_camera_h[:3] with the target camera's camera_matrix and distortion_coefficients. Extrinsic translations and 3D trajectories are both expressed in meters.
Time Alignment
All six videos in an episode share the same 30 FPS timeline. timestamps/episode_timebase.json records the episode-relative frame origin and duration. The 2D observations, 3D trajectories, semantic segments, and review video use the same episode-relative timebase.
Semantic Annotation
semantic/annotation.json provides bilingual task summaries and temporally ordered action segments. Each segment includes start and end times, action descriptions, actor roles, interaction phases, contact states, and manipulated objects.
Review Media
review/review.mp4 is a synchronized 1920 x 720, 30 FPS hand-trajectory visualization. For available 3D hand-frames, its displayed 2D skeleton is the six-camera reprojection of the delivered 3D trajectory rather than an independently estimated 2D result. review/annotation.html presents the video together with the semantic timeline. Numerical analysis should use the Parquet files and camera-calibration JSON as the authoritative sources.
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