shape_descriptor op• Data kinds: points → descriptor
• Call: import fullseye as fs; fs.ledger.a3_distribution(points, bins: 'int' = 64, samples: 'int' = 100000, seed: 'int' = 0) -> 'np.ndarray' (to call the implementation directly, import descriptors3d; descriptors3d.a3_distribution(points, bins: 'int' = 64, samples: 'int' = 100000, seed: 'int' = 0) -> 'np.ndarray'; from the registry, ops3d.get("a3_distribution"))
The distribution of the angle three random points (A, B, C) subtend at vertex B (Osada 2002's A3).
Angles are invariant to all of rotation, translation and scale (scaling does not change angles), so this is a dimensionless shape feature complementary to D2. Returns a normalised histogram with the fixed range [0, π] (bins,) (sum 1). Spatially coincident points (zero-length vectors) have undefined angles and are therefore excluded.
points : array_like, shape (N, 3)
Point cloud. N >= 3 is required.
bins, samples, seed :
Same meaning as in d2_distribution.
np.ndarray, shape (bins,)
Normalised angle histogram (radians, [0, π]).
• 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.
• shape_desc_pose — py -3.11 examples_3d/shape_desc_pose.py
descriptor as input)fuse_to_voxel · shape_distance
shape_descriptor)d2_distribution · extent_signature · describe · shape_distance
*Provenance: descriptors3d.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.