fly_tau_from_expansion — FLYVISION `looming` op

• 数据种类:signal → signal

• 调用: import fullseye as fs; fs.ledger.fly_tau_from_expansion(theta_signal, dt_s, shape='sphere')(要直接调用实现,import flyvision; flyvision.fly_tau_from_expansion(theta_signal, dt_s, shape='sphere');从台账取用则 opsflyvision.get("fly_tau_from_expansion"))

用法

> 该算子的说明尚无译文,以下照原文给出。

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.

详细使用指南

• fly_vision 族使用指南

参考(示例数据、文献)

• 示例数据目录(下载 URL / 许可证) —— 2-D 用 skimage.data(BSD/公有领域)加合成图,3-D 给出真实数据源(Stanford/PDS 等)的下载 URL。

• 算子来历与参考文献 —— 该算子族所依据的研究/方法出处。

• 算法的正典(作者、年份)与用途见上面的族使用指南。

可运行的示例(实际调用该算子并已验证的样例)

• poc_fly_vision — py -3.11 examples/poc_fly_vision.py

类型可衔接的下一个算子(可接受 `signal` 作为输入)

fly_hex_quantize · fly_emd_response · fly_lgmd_eta · fly_dsi

同类别(`looming`)

fly_lgmd_eta

*Provenance: flyvision.py — FLYVISION 算子登记表。本条目由 tools/opdocs.py md 自动生成(请勿手工编辑)。*

fly_tau_from_expansion — FLYVISION looming op

用法