shape_index — 3D curvature op

• Data kinds: points → descriptor

• Call: import curvature3d; curvature3d.shape_index(points, k=25, normals=None) (or ops3d.get("shape_index"))

Usage

Koenderink's shape index s∈[-1,1] (convex sphere +1, cylinder +0.5, saddle 0, concave sphere −1). → (N,).

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)

• curvature_grasp — py -3.11 examples_3d/curvature_grasp.py

• itokawa_curvature — py -3.11 examples_3d/itokawa_curvature.py

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

fuse_to_voxel · shape_distance

Same category (curvature)

principal_curvatures · mean_curvature · gaussian_curvature · estimate_normals

*Provenance: curvature3d.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.