canny3d — 3D edges op

• Data kinds: voxel → voxel

• Call: import fullseye as fs; fs.ledger.canny3d(vol, low: 'float', high: 'float', sigma: 'float' = 1.0) -> 'np.ndarray' (to call the implementation directly, import edges3d; edges3d.canny3d(vol, low: 'float', high: 'float', sigma: 'float' = 1.0) -> 'np.ndarray'; from the registry, ops3d.get("canny3d"))

Usage

3-D Canny edge detection (non-maximum suppression + hysteresis).

Parameters

vol : (D,H,W) array

Grey voxels.

low, high : float

Lower / upper hysteresis thresholds (on the gradient magnitude). 0 <= low <= high, high > 0.

sigma : float

Standard deviation of the smoothing.

Returns

edge_mask : (D,H,W) bool

Edges thinned to 1 voxel.

Notes

(1) get the smoothed gradient with gradient3d → (2) keep local maxima by NMS along the gradient direction (trilinear interpolation)

→ (3) grow with 26-connectivity at the low threshold from high-threshold seeds. The thresholds are absolute, so giving them on the scale of gmag.max() for the target is robust.

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.

Runnable examples (verified samples that actually call this op)

• edges_3d — py -3.11 examples_3d/edges_3d.py

Ops the type connects to (they accept voxel as input)

voxel_to_mips · voxel_to_mesh · signed_distance_field · to_points · sobel3d · hessian3d · curvature_maps · edt_jfa

Same category (edges)

gradient3d · log_zero_crossings · link_edges · edge_points

*Provenance: edges3d.py — 3D 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.