angle_3points — 3D geometry op

• Data kinds: points → measurement

• Call: import fullseye as fs; fs.ledger.angle_3points(a, b, c) (to call the implementation directly, import match3d; match3d.angle_3points(a, b, c); from the registry, ops3d.get("angle_3points"))

Usage

The angle at three points (vertex b, in degrees). ∠ABC.

> The detailed description below is the original text — the summary and the headings are translated.

`arccos(û·v̂)(u = a − b, v = c − b`)を度で返す(float)。値は [0, 180] で符号は

無い(2-D でも回転の向きは区別しない)。引数は数値の 2 または 3 ベクトル、次元の混在は

ValueError。`a == b か c == b` だと零ベクトルの内積 0 で 90 が返る(例外は出ない)。

内積は [−1,1] に clip するので数値誤差で NaN にはならない。

用途: 曲げ角・関節角の計測、`fit_line_3d` で得た 2 直線の交点まわりの角度。

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)

• geometry_metrology — py -3.11 examples_3d/geometry_metrology.py

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

vol_gaussian_psf · fuse_to_voxel · fresnel_reflectance · snell_angle

Same category (geometry)

line_from_2points · plane_from_3points · angle_between_lines · angle_between_planes · angle_line_plane · distance_point_plane · distance_point_line · distance_line_line

*Provenance: match3d.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.