The correlation discount is an effective-sample correction: with observations
correlated at rho, the n-th is worth n_eff(n+1) - n_eff(n) = 2/((n+1)(n+2))
at rho=0.5, so it decays quadratically and the total converges to 1/rho = 2.
That saturation is deliberate and stays — a long static shot must not
out-argue varied evidence purely by lasting longer.
What was not deliberate is that every scored face spent it. An observation at
p=0.02 contributes log(0.98) = -0.02 of belief, which is nothing, while
consuming the same increment as one at p=0.95. On SuperHero-2, track 3 carried
103 observations for an effective weight of 2.026 and a belief of 0.455
against a 0.881 threshold — with the 51 frames that *did* identify the actor
arriving when each was worth 0.0002. The budget had been spent by the frames
that recognised nobody.
It also made the answer depend on frame rate: deliver more frames, dilute the
budget with more non-matches, and a track that was owned stops being owned.
That is the defect AR-013 already had to fix once for reaping, still present
in accumulation. It is how this was found — SuperHero-2 identified Jeremy
before a KPN throughput fix and not after, from identical input, and bisect
put the change at the KPN bump in d98dc28 rather than anywhere in this repo.
The floor is 0.5, which is where the posterior stops favouring the hypothesis,
not a tuned threshold. Near-misses still count: the identity matcher
deliberately feeds every scored face rather than only accepted ones, and an
observation at 0.7 — under the matcher's 0.754 acceptance — still accumulates,
which the second test pins. Below 0.5 the observation argues *against*, which
noisy-OR cannot represent, so declining to spend a budget on it loses nothing.
Scored against the DVU knowledge-graph ground truth, all ten SuperHero scenes:
TP FP FN precision recall F1
before 9 0 15 1.000 0.375 0.545
after 13 0 14 1.000 0.481 0.650
Four more true positives and no false positives — the recall gain is not
bought with precision. Scene 7's Isabelle and scene 10's Isabelle and Jeremy
are all in the ground truth. Apples-to-apples over scenes 1-9 (scene 10's
before-run timed out): TP 9 to 11, FN 15 to 13, FP 0 either way.
An earlier attempt at this gave each actor its own budget. It was a no-op:
measured on the same track, n_obs_for[best] equalled n_obs at 103, because
every observation votes for the best-matching actor. Reverted rather than
kept.
151/151.
TRACES: AR-025, AR-013 | SR-002
dtourolle
7b73bf923a