obb — 3D bounds op

Data kinds: pointsprimitive

Call: import fullseye as fs; fs.ledger.obb(points) -> 'dict' (to call the implementation directly, import pcseg; pcseg.obb(points) -> 'dict'; from the registry, ops3d.get("obb"))

Usage

Oriented bounding box by PCA.

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

Returns ``{center, axes (3,3 columns = box axes), extents (3, half-widths),

corners (8,3)}``. The tight-fitting box a manipulator uses to reason about an

object's size and grasp width once it has been segmented out.

手順: 重心 `c を引いた点群の SVD(full_matrices=False)で主軸 axes`(列 = 特異値の降順、

第 1 列が最も広がる方向)を取り、点を主軸座標に写して各軸の min/max から半幅 `extents` と

箱中心 `center(重心とは一般に異なる)を求める。cornerscenter + (±extents) @ axes.T`

の 8 点で、符号の組合せは `meshgrid([-1,1],[-1,1],[-1,1])` の順。

• `points: (N,3) 以外は ValueError、2 点未満も ValueError`。

• PCA の主軸は「最小体積の箱」を保証しない(点の分布に沿うだけ)。主軸の符号は SVD の任意性で

決まり、点の分布が等方に近い(特異値が縮退する)と軸の向きは不安定になる。

• `extents は半幅なので辺長は 2 * extents`。単位は座標の単位。

Background guides (the physics and conventions behind this op)

blender_interop — Blender との併用 — 形を作って fullseye で測る(軸・単位・正解データの罠)

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)

hull_boundspy -3.11 examples_3d/hull_bounds.py

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

fuse_to_voxel · angle_between_lines · angle_between_planes · angle_line_plane · distance_point_plane · distance_point_line · distance_line_line · distance_segment_segment

Same category (bounds)

convex_hull · aabb · min_enclosing_sphere


*Provenance: pcseg.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.