label_components — 3D `regionprops` op

• Data kinds: voxel → labels

• Call: import fullseye as fs; fs.ledger.label_components(vol, connectivity: 'int' = 26) (to call the implementation directly, import regionprops3d; regionprops3d.label_components(vol, connectivity: 'int' = 26); from the registry, ops3d.get("label_components"))

• Return value through the ledger: fullseye.ledger.label_components(...) returns only the declared out type labels (the underlying function also returns auxiliary values). When you need what was dropped, use fullseye.ledger.label_components.raw(...) or call regionprops3d.label_components directly.

• Underlying return: (labels, n) → labels

Usage

Label a 3-D binary volume into connected components.

Parameters

vol : array_like

3D array of bool or 0/1.

connectivity : int

One of 6 (faces) / 18 (faces+edges) / 26 (faces+edges+corners).

Returns

labels : ndarray(int)

Same shape as vol. Background 0, labels 1..n for each connected component.

n : int

Number of connected components.

Notes:

• The input is binarised with astype(bool). Everything other than 0 is foreground; note that float NaN also becomes True (foreground).

• The axis order is (z, y, x) = numpy array axis order. The dtype of labels is the integer type returned by scipy.ndimage.label (usually int32). With no foreground / an empty array, an int32 zero array and 0 are returned.

• Labels are numbered in scipy's scan order, not by volume.

• Raises ValueError: input that is not 3-dimensional, connectivity other than 6/18/26.

• Touching objects merge into 1 component. If they must be separated, cut them beforehand with morph_erode3d / morph_open3d or vol_watershed.

• Downstream: region_props (measurement), largest_component / filter_by_volume (selection), vol_select_labels (screening by features), vol_colorize_labels (visualisation).

Background guides (the physics and conventions behind this op)

• measurement_uncertainty — Measurement uncertainty and calibration — what it takes to claim you are measuring

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)

• region_props_3d — py -3.11 examples_3d/region_props_3d.py

• watershed3d — py -3.11 examples_3d/watershed3d.py

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

fuse_to_voxel · vol_region_props

Same category (`regionprops`)

region_props · largest_component · filter_by_volume · inner_box3 · vol_label · vol_region_props

*Provenance: regionprops3d.py — 3D operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*

label_components — 3D regionprops op