vol_boundary_points — 3D `boundary` op

• Data kinds: voxel → points

• Call: import fullseye as fs; fs.ledger.vol_boundary_points(vol_binary, spacing=None, connectivity=6, origin=(0, 0, 0)) (to call the implementation directly, import volops; volops.vol_boundary_points(vol_binary, spacing=None, connectivity=6, origin=(0, 0, 0)); from the registry, ops3d.get("vol_boundary_points"))

Usage

Boundary shell as an `(N, 3) point cloud in (z, y, x)` order.

The bridge from the voxel world to the point-cloud world at minimal memory:

only the *surface* voxels of the mask become points (inner boundary, see

:func:vol_boundary), so a solid object of a million voxels typically

yields a few tens of thousands of points — ready for `fit_sphere3` /

`smallest_box3 / register_fpfh` and friends without ever materialising

the full grid as points.

Coordinates are `(index + origin) * spacing` per axis: pass *spacing*

`(sz, sy, sx) (or a :class:volio.VolumeMeta`) for physical millimetre

coordinates, and pass the offset returned by :func:vol_crop_domain as

*origin* so points from a cropped volume land in the uncropped frame

(*origin* is in voxel units — it is added to the index *before* the

spacing multiply; it must be finite, and may be fractional for a subvoxel

shift). An empty mask returns an empty `(0, 3)` array (a valid question

with a valid empty answer — unlike a crop, which needs a box to exist).

Returns an `(N, 3)` float64 array, rows ordered z-major (deterministic).

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)

• roi_domain_boundary — py -3.11 examples_3d/roi_domain_boundary.py

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

points_to_voxel · gaussians_to_voxel · estimate_point_normals · to_points · match_points_ncc · match_pca · moment_axes · icp_point2point_3d

Same category (`boundary`)

vol_boundary

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

vol_boundary_points — 3D boundary op