docs/caveats.md

# Known caveats and roadmap

For known sensor-level anomalies and the `bad_frames.json` skip-list, see [`quality.md`](quality.md).

## What this dataset is and isn't

React is a **dense multimodal interaction stream** intended for learning **dynamics / world models** over short multimodal windows. It is **not**:

- A demonstration / policy-learning dataset. "Episodes" here are just file boundaries — they don't carry semantic / action structure.
- Comparable apples-to-apples with BridgeData V2, DROID, RT-1, ALOHA, etc. on "number of demos." The relevant comparison is *hours of synchronized multimodal contact-rich interaction*.

## OT-uninitialized prefixes (already trimmed from `.pt`)

Three episodes on 2026-05-11 had OptiTrack offline at the moment the
operator pressed `s` to start recording. RealSense + GelSight kept
capturing fresh frames; OT held a stale (or zero) pose until the mocap
software came online:

| Episode | Trimmed prefix | What it was |
|---|---:|---|
| `episode_005` | 81 s (2,429 frames) | OT had ~50 samples in the prefix (~0.6 Hz) |
| `episode_012` | 324 s (9,719 frames) | OT had 3 samples in the prefix |
| `episode_017` | 641 s (19,228 frames) | OT had **zero** samples in the prefix |

**These prefixes have already been trimmed** from the published `.pt`
files. Each `.pt` records the trim amount in `_contact_meta.trim_offset`,
and all frame indices in `bad_frames.json` are in post-trim coordinates.
The original H5 recordings under `data/motherboard/2026-05-11/` remain
untouched in the recording-machine archive (not on HF).

**Fixed at the source**: future recordings use a `data_collection.py`
recorder-side watchdog that (a) refuses to start an episode unless every
active rigid body has streamed an OT sample in the last 2 s, and (b)
auto-saves + ends an in-progress episode after 10 s of OT silence on any
active body. The bug that produced these prefixes can no longer happen.

## OT track loss mid-episode (the remaining ~0.9 %)

After trimming the prefixes, the rest of the `ot_loss` intervals in
[`../bad_frames.json`](../bad_frames.json) are short (typically 1–3 s)
mid-episode mocap dropouts. Per `freeze_diagnose`'s cross-modal motion
check, the gel pad is still healthy and the cameras still capture — only
the OptiTrack solver lost the rigid body, usually because the operator's
hand moved near the edge of the mocap volume / camera FOV.

The shipped `bad_frames.json` flags these as `ot_loss_L` / `ot_loss_R`
and the example dataloader skips overlapping windows automatically when
`skip_bad_frames=True`.

**Mitigation for future recordings**: keep the workspace centred in the
mocap volume; add a fourth or fifth marker to each GelSight rigid body
so the solver tolerates more occlusion; add a fourth OT camera if budget
allows. None of these affect the current dataset retroactively — they're
just guidance for follow-up recording sessions.

## Other caveats

- **Missing / dropped files** on `motherboard/2026-05-11`:
  - `episode_000` and `episode_002` — short test recordings (8.8 s and
    10.4 s) with no tactile contact on either sensor; intentionally
    excluded.
  - `episode_001` — lost at recording time (HDF5 superblock never
    finalized when the writer was killed mid-write); intentionally absent.
  - The remaining episode IDs are non-contiguous as a result. **Don't
    infer ordering from filename gaps.**
- **Lossy resize**: the 128×128 `view` and tactile fields are downsampled
  from native 480×640. Native resolution is **not** preserved in this
  release.
- **Single camera**: only `realsense/cam0/color` is included in the
  `processed/.../*.pt` slice. The other two RealSense views (and depth
  streams) are recorded in the raw H5 archive but not exposed in
  `processed/mode1_v1/`.
- **OptiTrack alignment**: the per-step poses in `.pt` are nearest-neighbour
  matched to camera ticks. The full ~120 Hz pose streams are not
  preserved here.
- **Contact metrics are opinionated**: `tactile_{side}_{intensity, area, mixed}`
  depend on the chosen `tau` and the `p01` reference strategy. If you
  want a different `tau`, you'll need to re-derive them from raw GelSight
  frames.

## Roadmap

- **More tasks** — the registry in [`../tasks.json`](../tasks.json) will grow.
- **LeRobot-format full-fidelity** variant (`lerobot/v1.0/`) is planned.
  It will include all three RealSense color and depth streams, GelSight
  at native resolution (FFV1 lossless), full-rate OptiTrack pose tracks
  for all three rigid bodies, and HF-native browser previews. The current
  `processed/mode1_v1/` slice will remain as a stable training-task view.