Commit Graph
3 Commits
Author SHA1 Message Date
dtourolleandClaude Opus 5 0dbbe5f6a3 fix: belief accumulates across frames (lazy-OR), not once
A track recognised on 318 of 385 frames was owned on none, so the truth file
named nobody while the matcher was accepting almost continuously.

The correlation discount was an annihilator rather than an attenuator. Weight
was 1 - P(same view), so once a track had one stored view every later frame of
that same face scored ~0.01 and the belief stopped moving. One observation just
over the accept threshold is logit(0.78) ~ 1.27, under the ownership bar — hence
recognised always, owned never.

Two changes, in the order they were found.

Correlated evidence is now attenuated by effective sample size,
n_eff = n / (1 + (n-1)·rho), each frame contributing the marginal gain. That has
the right shape at both ends: uncorrelated evidence accumulates linearly, and a
held pose converges on 1/rho rather than growing without bound. A constant floor
was tried first and rejected — it grows linearly forever, so a long shot could
out-argue genuinely varied evidence purely by lasting longer.

Combination is now weighted lazy-OR: P = 1 - (1-P_old)·(1-p)^w, stored as
log(1-P) so the update is additive and precision stays where it matters as P
approaches 1. Each frame is new evidence that this track is that actor, and the
belief is the probability that at least one sighting was right. It converges
faster than summing log-odds at the same effective count — 2.98 vs 2.53 after
two observations at p=0.78 — which is what a real clip needs.

Note that summing log-odds was already a correct sequential Bayesian update:
the matcher fits with prior 0.5, so logit(p) IS the per-frame log-likelihood
ratio and the running sum carries the prior forward. It was not wrong, it was
slow. What blocked ownership was the discount, not the combination rule.

Also fixes a real correctness bug: the observation count lived on the
discounter, which is shared by every track, so tracks pooled into one effective
sample and each was discounted by how many others happened to be on screen. It
is now a per-track parameter.

The registry's frame scope holds its lock for its lifetime and the mutex is not
recursive, so calling observe() inside a scope self-deadlocks. The pipeline
never does — separate nodes — but the test did, and hung rather than failing.
Documented at the call site.

Verified end to end: the same clip that produced zero actors now identifies
Bing Crosby and Dorothy Lamour with belief 0.97.

Suite: 96 cases, 6142 assertions.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

TRACES: AR-025 | SR-002
2026-07-31 16:51:08 +02:00
dtourolleandClaude Opus 5 843852e19c feat: registry owns correlation discounting (AR-024, AR-025)
Moves two responsibilities inside the registry that callers should never have
been trusted with.

AR-025 — per-frame evidence is discounted for correlation by the registry
itself, via EvidenceDiscounter. Log-odds accumulation is only valid for
independent observations, and consecutive frames of one track are anything but:
near-identical pose, lighting and expression. Accumulated naively, thirty frames
of the same face at the same angle drive the posterior to certainty on what is
effectively one measurement.

Each observation is weighted by how much it adds — a view already contributed
counts for ~nothing, a genuinely new pose counts in full. This reuses the
novelty judgement gallery expansion already makes rather than inventing a second
one. The discounter is a separate class the registry holds, so it stays testable
and swappable, but it is a constructor argument rather than an option: there is
no correct way to accumulate without it.

AR-024 — observe() takes a calibrated probability and converts to log-odds
internally. A caller can no longer hand it a raw cosine, which would have been
silently wrong rather than obviously so. Retiring the remaining raw-cosine
constants in the tracker is still open.

DeadTrack now reports effective_obs alongside observations: the raw count and
the evidence that actually counted. A large gap between them is a track the
camera stared at, and worth seeing.

Three tests, one of which is the point: two tracks given the same number of
observations at the same posterior, one repeating a single view and one seeing
eight distinct ones, must not end up equally confident. Without discounting they
would be identical.

Fixed a test that asserted a belief swap on tied evidence. A tie leaves
ownership where it is — a challenger must out-accumulate the incumbent, since
one contrary observation is noise. The original test passed only because it fed
raw log-odds directly.

Suite: 78 cases, 3245 assertions. Coverage 20/63 to 22/63.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

TRACES: AR-024, AR-025 | SR-002
2026-07-31 09:15:44 +02:00
dtourolleandClaude Opus 5 f0c7126f80 feat: TrackRegistry — presence follows track extent
The spine of the redesign. Presence is now the extent of a track an actor owns,
[first_seen, last_seen], rather than the subset of frames in which recognition
happened to succeed. An actor recognised only at the end of a long track is
present for all of it, which is what the scene-scoped ground truth actually
records.

AR-013 — `last_seen` as an optional carries the entire liveness state: unset
means on screen, set means went off at that timestamp and still revivable,
reaped means emitted and erased. No missing-frame counter, no expired flag. It
subsumes the tracker's existing two-pool split, so there is no separate revival
path — matching a dormant track is ordinary inter-frame association.

The asymmetry is the point: interior gaps are claimed, the trailing cool-down is
not. A face lost and re-associated within the timeout never closed its track, so
the gap is presence — someone briefly occluded has not left the scene. But a
track that dies ends at its last sighting, never at the death time. That is
precisely the over-claim the retired extinction_sec keep-alive produced, where
presence ran on into the closing credits.

AR-014 — a belief swap A→B closes the track and opens a successor at the swap
frame. Not a correction: two non-twins both clearing the threshold on one face
is not realistic, whereas a track_id carried across a viewpoint change onto a
different person is. Treating it as a swap-and-continue would emit one window
blending two people; treating it as a boundary yields two that are each right.

AR-015 — two live tracks owned by one actor means at least one is wrong, since a
person cannot be in two places at once. A reverse index catches it on the update
that causes it rather than by scanning. This makes identity a third cut
detector, independent of the histogram and TransNetV2 and firing where those
failed.

AR-016 — flush() closes tracks still live at EOF. Without it a film ending
mid-shot silently drops its closing cast, which presents as a recognition miss
rather than a bookkeeping bug.

Reaping hands the dead track to the aggregator and erases it, so the registry
holds only live tracks and its size is bounded by concurrent on-screen faces
rather than growing with the film.

Locking: a frame's association pass is atomic as a unit via FrameScope, since
per-call locking would let another thread observe a half-updated frame.
owner() reads tally and verdict under one lock — separately, a track could be
both unowned and owned within a single promotion decision. A vote for an
already-reaped track is dropped and counted, because a nonzero count means the
timeout is shorter than the matcher's lag.

11 unit tests, driven directly against the registry with no network and no
fixture — the awkward cases are constructed rather than hunted for. Suite: 75
cases, 3236 assertions. Coverage 14/63 to 20/63.

Not yet wired into FaceTrackerFunc; that is AR-007/AR-008.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

TRACES: AR-012, AR-013, AR-014, AR-015, AR-016, AR-017 | SR-002
2026-07-31 09:08:39 +02:00