medial op• Data kinds: voxel → table
• Call: import fullseye as fs; fs.ledger.topology_signature(skeleton) (to call the implementation directly, import medial; medial.topology_signature(skeleton); from the registry, ops3d.get("topology_signature"))
Build a topology descriptor from the 26-neighbourhood degrees of a skeleton. Returns the counts of end points, junctions, ordinary points and isolated points.
For each skeleton voxel, counts the number of skeleton voxels in its 26-neighbourhood (degree) and
degree 1 = endpoint
degree 2 = normal point (middle of the skeleton)
degree>=3 = branch point (branch)
degree 0 = isolated point (isolated)
classifies it accordingly. The counts are invariant to translation and rotation (90 degrees), giving a descriptor that coarsely summarises the shape's topology.
Caution (honest): the 26-neighbourhood degree can be overcounted near branches due to diagonal adjacency (a known property of discrete skeletons). The endpoint count is exact at each branch tip, but the branch-point count can lean somewhat high.
Args:
skeleton: skeleton voxels (bool / 0-1 3D).
Returns:
dict: endpoints, branches, normal, isolated, total (total number of skeleton voxels),
degree_hist (degree -> count).
• 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.
• medial_topology — py -3.11 examples_3d/medial_topology.py
table as input)fuse_to_voxel · mesh_select_lod
medial)distance_ridge · skeletonize_vol · medial_axis_points · medial_match · skeleton_junctions3d · skeleton_endpoints3d · skeleton_prune3d · skeleton_branches3d
*Provenance: medial.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.