Replace per-track line-crossing counter with a single event state machine
gated by foreground pixel count (ENTER=250, EXIT=150) and finalized by
quiet-exit or timeout. Direction inferred from centroid excursion
(up_score vs down_score) on quiet-exit fires, and from net displacement
(last_c vs first_c) on timeout fires.
Tuning reflects bench data at the intended 7' overhead mount: walkers
produce smaller centroid excursions than originally modelled, so
EXTENT gates, MIN_TRAJ, MAX_FRAMES and REFRACTORY were all relaxed from
their initial guesses. Constants and rationale live in firmware/lib/cv/cv.h.
Bench results (8 isolated walks, 4 entries + 4 exits):
* Event detection: 8/8 (100%)
* Aggregate entries+exits split: 4+4 (matches)
* Per-walk direction labelling: 4/8 (~50%)
Document explicitly that per-walk direction is unreliable at this mount
and that downstream analytics should trust only gross traffic
(entries + exits). Recovering direction would require a physical mount
change or a richer signal; both are out of scope for v1.
Tooling:
* tools/replay_logs.py — replay event state machine against captured
[F] diagnostic lines, for offline tuning without flash-test loops.
* firmware/src/main_capture.cpp + tools/capture_frames.py +
tools/replay_frames.py — raw-frame capture firmware and Python port
of the detector, kept in tree for future iteration even though the
TimerCamera-F serial driver stripped specific byte ranges in testing
and log-based replay became the working path.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Peter Woolery
a37207b6ff