estimate_alpha — 3D `reconstruct` op

• Data kinds: points → measurement

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

Usage

Return a recommended alpha from the point set's scale (based on the median nearest-neighbour distance).

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

各点の最近傍距離の中央値 `m` を求め、半径しきい値 1/alpha ≈ 2m(隣接間隔の約 2 倍まで

許す)となるよう `alpha = 1/(2m)` を返す。これで表面付近の素性の良い四面体は残しつつ、

大きく間延びした四面体(=凹み・外側)を切り落とせる。重複点は最近傍 0 になるため正の距離のみ使う。

Parameters

----------

points : array_like (N,3)

Returns

-------

alpha : float

正の有限値。

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)

• alpha_shape_topology — py -3.11 examples_3d/alpha_shape_topology.py

• sfm_recon — py -3.11 examples_3d/sfm_recon.py

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

vol_gaussian_psf · fuse_to_voxel · fresnel_reflectance · snell_angle

Same category (`reconstruct`)

poisson_lite · alpha_shape_mesh · alpha_shape_boundary

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

estimate_alpha — 3D reconstruct op