alpha_shape_boundary — 3D `reconstruct` op

• Data kinds: points → indices

• Call: import fullseye as fs; fs.ledger.alpha_shape_boundary(points, alpha) (to call the implementation directly, import recon3d; recon3d.alpha_shape_boundary(points, alpha); from the registry, ops3d.get("alpha_shape_boundary"))

Usage

The indices of the boundary points by alpha shapes (point set → boundary points).

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

Delaunay 四面体分割の外接球半径 < 1/alpha の四面体の表面三角形(境界面)を集め、その頂点

集合を境界点とする。中実(表面+内部)の点群から表面殻の点だけを抜き出す用途に向く。

alpha を大きくすると許す半径 1/alpha が小さくなり、より密着した(細部を拾う)境界になる。

Parameters

----------

points : array_like (N,3)

alpha : float

正の実数。半径しきい値は 1/alpha。`estimate_alpha` で目安を得られる。

Returns

-------

boundary_point_indices : numpy.ndarray (K,) int64

points に対する境界点の index(昇順・重複なし)。境界が無ければ空配列。

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)

• sfm_recon — py -3.11 examples_3d/sfm_recon.py

Ops the type connects to (they accept `indices` as input)

fuse_to_voxel

Same category (`reconstruct`)

poisson_lite · alpha_shape_mesh · estimate_alpha

*Provenance: recon3d.py — 3D operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*

alpha_shape_boundary — 3D reconstruct op