typed op• Data kinds: signal → signal
• Call: fullseye.apply(img, "tb_fly_lgmd_eta", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])
*The figure is the actual output on a synthetic 128×128 input. Left: input, right: output. Point clouds are drawn as a top-down scatter (brightness = z), 1-D series as a line plot, volumes as the maximum-intensity projection along z, videos as the middle frame, complex images as magnitude; return values that are not pictures are shown as the values themselves.*
Sweeping knob a (0.1 / 0.5 / 0.9, the other knob at its default):
▸ tb_fly_lgmd_eta: knob a sweep (docs site)
*Knob b does not change the output (measured: identical at 0.1 / 0.5 / 0.9).*
Stages (the ops that come before → this op, left to right):
▸ tb_fly_lgmd_eta: stages (docs site)
On other images (synthetic scene / photo / coins. Top row: inputs, bottom row: their outputs. Knobs at default):
▸ tb_fly_lgmd_eta: other inputs (docs site)
LGMD/eta looming response from an expanding subtended angle.
The multiplicative looming model::
eta(t) = theta'(t - delay) * exp(-alpha * theta(t - delay))
where *theta_signal* is the object's full subtended angle over time, in
radians. The product of the angular expansion rate and an exponentially
decaying gain gives a response that peaks a fixed time before collision.
theta_signal: the full subtended angle per sample, radians.
dt_s: the sample interval, seconds.
alpha: the gain-decay constant.
delay_s: a fixed neural delay, seconds.
Returns a 1-D float64 array `eta(t)` of the same length.
Ground truth: for an object of half-size `l approaching at speed |v|`,
`eta peaks at a time-to-contact of alpha*l/|v| - delay_s` (Gabbiani et
al. Eq. 5), where the subtended angle is exactly `2*atan(1/alpha)` (Eq. 6;
24.0 degrees for `alpha = 4.7`) — both 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*
/ *alpha*, and a negative *delay_s*.
Typed bridge of the flyvision op `fly_lgmd_eta into the 2-D evolution registry: the same implementation, called under the op(v, a, b) convention. a drives alpha (default 4.7); b` is unused.
• Sample-data catalog (download URLs / licences) — 2-D uses skimage.data (BSD/public domain) plus synthetic images; 3-D lists download URLs for real data sources (Stanford, PDS, …).
• Operator provenance and references — the sources of the research/methods this op family came from.
The program below has been verified to run (same input as the figure). In Studio's help this block becomes buttons that load and run it on the spot.
img_to_signal 0.50 0.50 tb_fly_lgmd_eta 0.50 0.50
▸ Load this pipeline · Load & run
The examples below call the underlying ledger op fly_lgmd_eta. This bridge op is the same implementation adapted to the fn(v, a, b) convention, so the behaviour carries over unchanged (only the call form differs).
• poc_fly_vision — py -3.11 examples/poc_fly_vision.py
signal as input)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 operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.