| # No-contact reference frames — how they're chosen & used |
|
|
| A GelSight difference image / contact metric is computed relative to a |
| **no-contact reference** (the resting gel). This folder ships one per session and |
| documents how to pick a per-episode reference, how to build the no-contact |
| **pool**, and the caveat for a reference **latent**. |
|
|
| ## How the reference is selected |
|
|
| Each episode is a cut from one continuous per-day recording (`episodes.jsonl` |
| `date`), so all episodes of a day share the same gel & lighting. |
|
|
| 1. **Primary — per-episode fuzzy mode** (`toolbox.reference.fuzzy_mode_background`): |
| the per-pixel temporal *mode* of the episode is the resting gel even when a |
| pixel is in contact part of the time (robust past the median's 50%-occupancy |
| limit). Drift-free (it is the episode's own gel state). Preferred whenever the |
| episode has clean frames — **63/64 sides**. |
| 2. **Fallback — session reference** (`toolbox.reference.session_reference`, |
| shipped as `<date>/tactile_{left,right}.png`): for a clip that is in contact |
| its *entire* length its own mode is contaminated. Pool the whole day (any |
| pixel is untouched most of the day) to recover the rest gel, then use it to |
| **label that episode's own clean frames**. Example: `2026-05-19 ep003 left` |
| (121 frames, all contact vs its own mode) → the session reference finds **26 |
| real no-contact frames** in it (indices 17–21, 53–73). |
|
|
| > Do **not** use `get_reference(mode="p01")` (quietest single frame): it can pick |
| > a marginal or contact frame, and returns a contact frame outright when no clean |
| > frame exists — inverting the difference image. Audit: 2/64 p01 anchors were |
| > contact frames. |
| |
| Caveat: the session reference carries intra-day **gel drift**, so it differs from |
| a given episode by a diffuse global amount (~0.37 area, no object — see |
| `drift_check.png`). Use it only to label all-contact episodes; prefer the |
| per-episode mode otherwise. |
|
|
| ## How to use it |
|
|
| **Shipped references (ready to use, native 640×480):** |
|
|
| - `per_episode/<date>/<episode>_<side>.png` — the **per-episode** rest gel |
| (primary; fuzzy mode of that episode). One per episode-side. `ep003 left` |
| (all-contact) ships its session reference instead (see `per_episode/manifest.json`). |
| - `<date>/tactile_{left,right}.png` — the **per-session** rest gel (fallback / |
| day-level). |
|
|
| ```python |
| import imageio.v2 as imageio |
| from toolbox import load_video, difference, contact_metrics, l2_diff |
| import numpy as np |
| |
| frames = load_video("data/motherboard/videos/2026-05-11/episode_016/tactile_right.mp4") |
| ref = imageio.imread("data/motherboard/reference/per_episode/2026-05-11/episode_016_right.png") |
| |
| diff = difference(frames[t], ref) # Sparsh-style signed difference image |
| m = contact_metrics(frames[t], ref) # {intensity, area, mixed} |
| area = np.array([(l2_diff(f, ref) > 8).mean() for f in frames]) |
| pool = np.where(area < 0.01)[0] # the episode's no-contact reference pool |
| ``` |
|
|
| To recompute a reference yourself (e.g. at another resolution / with in-bin |
| refinement) use `fuzzy_mode_background(frames)` (per-episode) or |
| `session_reference([...])` (per-day); `toolbox/build_session_references.py` |
| rebuilds the whole set. Shipped PNGs are the per-pixel mode (bin width 8). |
|
|
| ```python |
| from toolbox import load_video, fuzzy_mode_background, session_reference, difference, contact_metrics, l2_diff |
| |
| frames = load_video(paths["tactile_left"]) # (T,H,W,3) uint8 |
| ref = fuzzy_mode_background(frames) # (H,W,3) rest gel |
| |
| diff = difference(frames[t], ref) # Sparsh-style signed diff |
| m = contact_metrics(frames[t], ref) # {intensity, area, mixed} |
| |
| # no-contact pool = frames whose gel is at rest: |
| area = np.array([ (l2_diff(f, ref) > 8).mean() for f in frames ]) |
| pool = np.where(area < 0.01)[0] # reference-frame pool |
| ``` |
|
|
| ### Reference **latent** — the whole window must be no-contact |
|
|
| If you encode with a **video** tokenizer (e.g. Cosmos), a frame's latent depends |
| on its entire temporal window (Cosmos CV4x8x8: `ti=0` is a single frame, `ti≥1` |
| encodes a 4-frame group). A frame can itself be no-contact while its window/group |
| straddles a contact boundary — then the **latent bakes in contact** even though |
| the frame is clean. Audit: this inflated one episode's background floor from 0.05 |
| to 0.11 and produced a spurious contact "artifact" in every delta map. |
|
|
| **Rule:** for a clean reference *latent*, require **every frame in the encoder's |
| window** to be no-contact, not just the anchor frame: |
|
|
| ```python |
| # a latent frame (window start s, group g) is a valid reference iff the WHOLE |
| # group is no-contact: |
| group = [s] if ti == 0 else range(s + 1 + (ti-1)*4, s + 1 + ti*4) # Cosmos ti map |
| valid = all(area[r] < 0.01 for r in group) |
| ``` |
|
|
| For an image tokenizer this is unnecessary (each frame encodes independently); a |
| Cosmos `ti=0` latent is equivalent to a single-image encode (verified to 0.8%). |
|
|
| ## Preview — 20 reference frames per episode |
|
|
| `previews/<date>/<episode>_<side>.png` shows 20 frames sampled from each |
| episode-side's no-contact pool (labelled `f<frame> a<area>`). Every episode-side |
| has a real, non-empty pool (median ~2145 frames, ~56% of the clip; min 26 for |
| `ep003 left` via the session fallback). Pool sizes are in `previews/pool_manifest.json`. |
|
|
| --- |
|
|
| ## Preview gallery — 20 reference frames per episode-side |
|
|
| Each grid = 20 frames sampled from that episode-side's no-contact pool (`f<frame> a<area>`). `pool=` is the full pool size; `via` = which reference labeled it. |
|
|
| ### 2026-05-10 |
| **episode_000 left** — pool=3534 (episode mode) |
|  |
| **episode_000 right** — pool=4762 (episode mode) |
|  |
|
|
| **episode_001 left** — pool=4405 (episode mode) |
|  |
| **episode_001 right** — pool=5799 (episode mode) |
|  |
|
|
| **episode_002 left** — pool=6606 (episode mode) |
|  |
| **episode_002 right** — pool=7455 (episode mode) |
|  |
|
|
| **episode_003 left** — pool=4653 (episode mode) |
|  |
| **episode_003 right** — pool=4979 (episode mode) |
|  |
|
|
| **episode_004 left** — pool=908 (episode mode) |
|  |
| **episode_004 right** — pool=591 (episode mode) |
|  |
|
|
| **episode_005 left** — pool=342 (episode mode) |
|  |
| **episode_005 right** — pool=477 (episode mode) |
|  |
|
|
| **episode_006 left** — pool=1705 (episode mode) |
|  |
| **episode_006 right** — pool=1133 (episode mode) |
|  |
|
|
| **episode_007 left** — pool=1092 (episode mode) |
|  |
| **episode_007 right** — pool=1039 (episode mode) |
|  |
|
|
| **episode_008 left** — pool=769 (episode mode) |
|  |
| **episode_008 right** — pool=760 (episode mode) |
|  |
|
|
| **episode_009 left** — pool=1154 (episode mode) |
|  |
| **episode_009 right** — pool=807 (episode mode) |
|  |
|
|
| **episode_010 left** — pool=403 (episode mode) |
|  |
| **episode_010 right** — pool=583 (episode mode) |
|  |
|
|
| **episode_011 left** — pool=915 (episode mode) |
|  |
| **episode_011 right** — pool=743 (episode mode) |
|  |
|
|
| ### 2026-05-11 |
| **episode_003 left** — pool=6550 (episode mode) |
|  |
| **episode_003 right** — pool=7148 (episode mode) |
|  |
|
|
| **episode_004 left** — pool=1786 (episode mode) |
|  |
| **episode_004 right** — pool=1844 (episode mode) |
|  |
|
|
| **episode_005 left** — pool=8123 (episode mode) |
|  |
| **episode_005 right** — pool=9523 (episode mode) |
|  |
|
|
| **episode_006 left** — pool=7565 (episode mode) |
|  |
| **episode_006 right** — pool=7654 (episode mode) |
|  |
|
|
| **episode_007 left** — pool=4624 (episode mode) |
|  |
| **episode_007 right** — pool=3903 (episode mode) |
|  |
|
|
| **episode_008 left** — pool=8769 (episode mode) |
|  |
| **episode_008 right** — pool=5793 (episode mode) |
|  |
|
|
| **episode_009 left** — pool=2718 (episode mode) |
|  |
| **episode_009 right** — pool=1850 (episode mode) |
|  |
|
|
| **episode_010 left** — pool=4491 (episode mode) |
|  |
| **episode_010 right** — pool=4117 (episode mode) |
|  |
|
|
| **episode_011 left** — pool=5060 (episode mode) |
|  |
| **episode_011 right** — pool=4518 (episode mode) |
|  |
|
|
| **episode_012 left** — pool=9042 (episode mode) |
|  |
| **episode_012 right** — pool=7426 (episode mode) |
|  |
|
|
| **episode_013 left** — pool=9224 (episode mode) |
|  |
| **episode_013 right** — pool=7176 (episode mode) |
|  |
|
|
| **episode_014 left** — pool=1413 (episode mode) |
|  |
| **episode_014 right** — pool=1044 (episode mode) |
|  |
|
|
| **episode_015 left** — pool=3881 (episode mode) |
|  |
| **episode_015 right** — pool=3433 (episode mode) |
|  |
|
|
| **episode_016 left** — pool=6756 (episode mode) |
|  |
| **episode_016 right** — pool=7268 (episode mode) |
|  |
|
|
| **episode_017 left** — pool=636 (episode mode) |
|  |
| **episode_017 right** — pool=2441 (episode mode) |
|  |
|
|
| ### 2026-05-19 |
| **episode_000 left** — pool=289 (episode mode) |
|  |
| **episode_000 right** — pool=358 (episode mode) |
|  |
|
|
| **episode_001 left** — pool=149 (episode mode) |
|  |
| **episode_001 right** — pool=295 (episode mode) |
|  |
|
|
| **episode_002 left** — pool=568 (episode mode) |
|  |
| **episode_002 right** — pool=575 (episode mode) |
|  |
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|
| **episode_003 left** — pool=26 (session ref (fallback)) |
|  |
| **episode_003 right** — pool=65 (episode mode) |
|  |
|
|
| **episode_004 left** — pool=52 (episode mode) |
|  |
| **episode_004 right** — pool=90 (episode mode) |
|  |
|
|
