alias op• データ種: signal × table → table
• 呼び出し: import 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"))
標本化した信号の最強の低周波成分がどれだけ鋭いか —— 格子が解像できない模様から作るモアレの尖り。
> 以下の詳細説明は原文のままです —— 要約と見出しは訳出済み。
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 (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 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*.
• サンプルデータ カタログ(DL URL / ライセンス) — 2-D は skimage.data(BSD/public)+ 合成、3-D は実データ源(Stanford/PDS 等)の DL URL。
• 演算子の来歴・参考文献 — この op 族の元になった研究/手法の出典。
• アルゴリズムの正典(著者・年)と用途は上記ファミリ使い方ガイドに記載。
• poc_moire_screen — py -3.11 examples/poc_moire_screen.py
• poc_print_registration — py -3.11 examples/poc_print_registration.py
• poc_zebra_stripes_fly_eye — py -3.11 examples/poc_zebra_stripes_fly_eye.py
table 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.