typed op• 数据种类:signal → signal
• 调用:fullseye.apply(img, "tb_fly_tau_from_expansion", a=0.5, b=0.5)(2-D 的模型是一张图 + 两个标量旋钮 a,b∈[0,1])
*图为在 128×128 合成输入上实际运行的输出。左为输入，右为输出。点云以俯视散点显示(亮度 = z)，一维序列为折线，体数据为沿 z 的最大值投影，视频为中间帧，复数图像为幅值；无法成像的返回值直接显示数值。*
*旋钮 a 不改变输出(实测: 0.1 / 0.5 / 0.9 相同)。*
*旋钮 b 不改变输出(实测: 0.1 / 0.5 / 0.9 相同)。*
阶段(前置算子 → 本算子，从左到右):
▸ tb_fly_tau_from_expansion: stages (docs site)
换别的图像(合成场景 / 照片 / 硬币。上排为输入，下排为对应输出。旋钮取默认):
▸ tb_fly_tau_from_expansion: other inputs (docs site)
> 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 :data: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.
Typed bridge of the flyvision op `fly_tau_from_expansion into the 2-D evolution registry: the same implementation, called under the op(v, a, b) convention. This op has no tunable parameter; a and b` are unused.
• 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。
下面的程序已确认可以运行(与图相同的输入)。在 Studio 帮助中，此块会变成按钮，可当场加载并运行。
img_to_signal 0.50 0.50 tb_fly_tau_from_expansion 0.50 0.50
▸ Load this pipeline · Load & run
下面的示例调用的是底层账本算子 fly_tau_from_expansion。此桥接算子只是把同一实现适配为 fn(v, a, b) 约定，行为完全相同(只是调用形式不同)。
• poc_fly_vision — py -3.11 examples/poc_fly_vision.py
signal 作为输入)identity · tb_create_funct_1d_array · tb_smooth_funct_1d_gauss · tb_smooth_funct_1d_mean · tb_derivate_funct_1d · tb_integrate_funct_1d · tb_zero_crossings_funct_1d · tb_abs_funct_1d
typed)tb_points_to_voxel · tb_estimate_point_normals · tb_iss_keypoints · tb_project_points · tb_render_point_depth · tb_statistical_outlier_removal · tb_radius_outlier_removal · tb_voxel_grid_downsample
*Provenance: ops.py — 2D 算子登记表。本条目由 tools/opdocs.py md 自动生成(请勿手工编辑)。*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.