fly_hex_lattice — FLYVISION `lattice` op

• Data kinds: none → table (an op determined by its arguments alone — it takes no image or data input)

• Call: import fullseye as fs; fs.ledger.fly_hex_lattice(radius=15, dphi_deg=4.63, az0_deg=0.0, el0_deg=0.0, geometry='regular') (to call the implementation directly, import flyvision; flyvision.fly_hex_lattice(radius=15, dphi_deg=4.63, az0_deg=0.0, el0_deg=0.0, geometry='regular'); from the registry, opsflyvision.get("fly_hex_lattice"))

Usage

Hexagonal ommatidial lattice: viewing directions of a compound eye.

A hexagon of `n = 3*radius*(radius+1)+1` ommatidia on axial coordinates

`(u, v) with -radius <= u <= radius` and

`max(-radius, -radius-u) <= v <= min(radius, radius-u)` (u outer, v inner),

each given an azimuth, an elevation and a unit viewing direction in body

coordinates (x forward, y left, z up; `az = atan2(y, x)` left positive,

`el = asin(z)`).

`geometry="regular": az = az0 + dphi*(v + u/2)`,

`el = el0 + dphi*(sqrt(3)/2)*u` — an isotropic hexagon.

`geometry="boxeye"`: the pixel-grid distortion of the connectome-derived

models, `pixel (y, x) = (13*(u + v/2), 13*v) with 13 px = dphi`, so

`az = az0 - v*dphi and el = el0 - (u + v/2)*dphi`; the diagonal neighbour

is 1.118x the axial spacing.

radius: the hexagon radius in ommatidia.

dphi_deg: the inter-ommatidial angle in degrees.

az0_deg / el0_deg: the direction of the lattice centre (the optical axis).

geometry: one of :data:GEOMETRIES.

Returns a dict ``{"uv": (n,2) int, "az_rad": (n,), "el_rad": (n,),

"dirs": (n,3) unit vectors, "dphi_rad": float, "geometry": str}``.

Ground truth: `n == 3*radius*(radius+1)+1 exactly, every dirs` row is a

unit vector, and for `"boxeye"` the ratio of the diagonal to the axial

nearest-neighbour angular spacing is 1.118 (both pinned in the tests).

Raises `ValueError: a *radius* outside [1, MAX_LATTICE_RADIUS]`, a

non-positive *dphi_deg*, a non-real / non-finite / string / bool angle, and an

unknown *geometry*.

References (sample data, literature)

• 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 canonical algorithm (author, year) and its uses are named in the family usage guide above.

Runnable examples (verified samples that actually call this op)

• poc_fly_vision — py -3.11 examples/poc_fly_vision.py

• poc_print_registration — py -3.11 examples/poc_print_registration.py

Ops the type connects to (they accept `table` as input)

fly_hex_resample · fly_hs_readout

Same category (`lattice`)

—

*Provenance: flyvision.py — FLYVISION operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*

fly_hex_lattice — FLYVISION lattice op