looming op• Datenarten: signal → signal
• Aufruf: import fullseye as fs; fs.ledger.fly_tau_from_expansion(theta_signal, dt_s, shape='sphere') (die Implementierung direkt: import flyvision; flyvision.fly_tau_from_expansion(theta_signal, dt_s, shape='sphere'); aus dem Register: opsflyvision.get("fly_tau_from_expansion"))
> Für diesen Operator gibt es noch keine Übersetzung. Es folgt der Originaltext unverändert.
Time-to-contact from optical expansion — the tau margin.
From the subtended angle and its rate::
shape="disk": tau = sin(theta) / theta'
shape="sphere": tau = 2*tan(theta/2) / theta'
theta_signal is the full subtended angle over time, radians.
★ The two object models differ by 33% at a 60-degree subtense (sin 60 = 0.866 vs 2 tan 30 = 1.155); using the wrong one silently mis-times a landing, so the model is a required, named choice rather than a default guess.
theta_signal: the full subtended angle per sample, radians.
dt_s: the sample interval, seconds.
shape: "disk" (a frontal circular disk) or "sphere".
Returns a 1-D float64 array of the time-to-contact per sample, seconds. Non-expanding samples (theta' <= 0) return NaN — a documented non-finite, because a contracting or static angle has no time-to-contact and inventing one would be a plausible-wrong number. (The registry op tb_fly_tau_from_expansion must return a finite signal, so it replaces those NaN by the signal fallback without recording a fallback event — backend_safe.NONFINITE_BY_DESIGN; call this function directly to keep the NaN.)
Ground truth: for the model's own object geometry (theta = 2 asin(l/d) for a sphere, theta = 2 atan(l/d) for a disk) approaching at speed |v|, the returned tau equals the true distance-over-speed d/|v| (pinned in the tests).
Raises ValueError: a non-1-D / empty / too-short (< 3) / non-finite *theta_signal*, a signal over MAX_SIGNAL_POINTS, a non-positive *dt_s*, and an unknown *shape*. A non-expanding angle is not an error — it is the documented NaN return above.
• Leitfaden zur Familie fly_vision
• Katalog der Beispieldaten (Download-URLs / Lizenzen) — 2-D nutzt skimage.data (BSD/Public Domain) plus synthetische Bilder, 3-D nennt Download-URLs echter Datenquellen (Stanford, PDS, …).
• Herkunft und Literatur der Operatoren — die Quellen der Forschung/Verfahren, auf denen diese Operatorfamilie beruht.
• Der kanonische Algorithmus (Autor, Jahr) und seine Anwendungen stehen im Familienleitfaden oben.
• poc_fly_vision — py -3.11 examples/poc_fly_vision.py
signal als Eingabe)fly_hex_quantize · fly_emd_response · fly_lgmd_eta · fly_dsi
looming)*Provenance: flyvision.py — FLYVISION Operator-Registry. Diese Notiz wird von tools/opdocs.py md erzeugt (nicht von Hand bearbeiten).*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.