integrate op• Data kinds: matrix × table → measurement
• Call: import fullseye as fs; fs.ledger.fly_hs_readout(responses, lattice, n_pref, el_min_deg=0.0, rectify=True) (to call the implementation directly, import flyvision; flyvision.fly_hs_readout(responses, lattice, n_pref, el_min_deg=0.0, rectify=True); from the registry, opsflyvision.get("fly_hs_readout"))
Horizontal-system wide-field readout: opponent sum over the upper field.
Given a stack of motion-detector responses over the ommatidia — the first
*n_pref* rows the preferred-direction type, the rest the anti-preferred — the
opponent readout over the ommatidia above the horizon is::
(a - b) / (a + b + 1e-6)
where `a and b` are the (optionally rectified) totals of the preferred
and anti-preferred responses over the columns with `el > el_min_deg`.
Only the upper visual field is used because the ground flow of forward motion
is `1/distance` while the rotational flow it must be separated from is
distance-independent: an eye 1.2 mm above the floor sees floor flow of
330-1000 deg/s, above the ~200 deg/s bandwidth of the motion detectors, so the
lower field carries speed the correlator cannot read and is excluded.
responses: a `(k, n) matrix of responses, n` matching the lattice.
lattice: the dict returned by :func:fly_hex_lattice.
n_pref: how many leading rows are the preferred-direction type
(`1 <= n_pref < k`).
el_min_deg: the horizon; only ommatidia above it contribute.
rectify: half-wave rectify (clip negatives to 0) before summing.
Returns the opponent ratio as a float in `[-1, 1]`.
Ground truth: with the preferred rows active only in the upper field and the
anti-preferred rows silent, the readout is `+1` (and the sign and value
match the hand calculation); an `el_min_deg` above every ommatidium raises
(pinned in the tests).
Raises `ValueError`: a non-2-D / empty / non-finite *responses*, a
*responses* over the element cap, a *lattice* that is not a
:func:fly_hex_lattice result, a column count not matching the lattice, a
*n_pref* outside `[1, k-1]`, a non-real *el_min_deg*, a non-bool *rectify*,
and an *el_min_deg* above every ommatidium (no upper field to read).
• Sample-data catalog (download URLs / licences) — 2-D uses skimage.data (BSD/public domain) plus synthetic images; 3-D lists download URLs for real data sources (Stanford, PDS, …).
• Operator provenance and references — the sources of the research/methods this op family came from.
• The canonical algorithm (author, year) and its uses are named in the family usage guide above.
• poc_fly_vision — py -3.11 examples/poc_fly_vision.py
measurement as input)—
integrate)—
*Provenance: flyvision.py — FLYVISION operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.