alias opsignal × table → tableimport fullseye as fs; fs.ledger.lattice_moire_peak(signal, lattice, fmax_cycles_per_deg=0.0, n_freq=48, window='hann') (実装を直接呼ぶなら import flyvision; flyvision.lattice_moire_peak(signal, lattice, fmax_cycles_per_deg=0.0, n_freq=48, window='hann')、台帳から引くなら opsflyvision.get("lattice_moire_peak"))How sharp the strongest low-frequency component of a sampled signal is — the moire a lattice makes of a texture it cannot resolve.
Sampling a texture above the lattice’s Nyquist limit does not lose it; it
folds it to a lower frequency. On a regular lattice the fold is a single
sharp peak — a false stripe the next stage reads as a real one — and on an
irregular arrangement the same energy spreads into a ring. This op measures
that difference as a number: the non-uniform discrete Fourier transform of
the ommatidial signal (mean removed, radially windowed) at the gnomonic
positions of the ommatidia, over a grid of n_freq x n_freq frequencies
up to fmax_cycles_per_deg (0 = the lattice’s own hexagonal Nyquist
1/(sqrt 3 dphi), the band the eye can represent), and the ratio of the
highest amplitude on that grid to the median amplitude.
signal: (n,) ommatidial values (:func:fly_view_plane_texture).
lattice: the eye they were sampled on — any geometry; only directions are used.
fmax_cycles_per_deg: the half-width of the frequency grid, cycles/degree.
n_freq: grid side, 8 <= n_freq <= MAX_MOIRE_FREQ.
window: one of :data:MOIRE_WINDOWS — a radial Hann taper over the field
(default: the field edge is a step and would leak everywhere).
Returns a dict {"peak_ratio", "peak_cycles_per_deg", "peak_amplitude",
"background_median", "nyquist_cycles_per_deg", "n_freq"}.
Ground truth (pinned in the tests): a sinusoid just below Nyquist sampled on the hexagonal eye gives a peak ratio above 30; the same sinusoid on a Vogel eye of the same count and mean spacing gives a peak ratio at least 2.5x smaller — the energy that was one peak is now a ring.
Raises ValueError: a signal that is not (n,) for this lattice
(an empty signal is refused), non-finite entries, a constant signal (there
is no spectrum to rank — its ratio would be 0/0), a negative fmax, an
n_freq outside its range, an unknown window, and a malformed lattice.
py -3.11 examples/poc_moire_screen.pypy -3.11 examples/poc_print_registration.pypy -3.11 examples/poc_zebra_stripes_fly_eye.pytable を入力に取れる)fly_t4t5_field · fly_flow_from_directions · fly_matched_filter · fly_egomotion_from_flow · fly_eye_merge · fly_view_plane_texture · fly_hex_resample · fly_expansion_readout
alias)Provenance: flyvision.py — FLYVISION operator registry. この per-op ノートは tools/opdocs.py md が自動生成(手編集しない)。
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.