volume_downsample — 3D `preprocess` op

• データ種: voxel → voxel

• 呼び出し: import fullseye as fs; fs.ledger.volume_downsample(vol, factor, mode='mean') (実装を直接呼ぶなら import volops; volops.volume_downsample(vol, factor, mode='mean')、台帳から引くなら ops3d.get("volume_downsample"))

使い方

Block-pool a `(D, H, W)` volume by an integer *factor* per axis (data 間引き).

Large CT / laminography / simulation volumes must be thinned before the

heavier 3-D operators (Frangi/Sato are capped at ~256**3 voxels, see

`MAX_EIGEN_VOXELS`). This is the volume analogue of the point-cloud

`voxel_grid_downsample and the mesh decimate_qem` — the third leg of

Fullseye's *間引き* (decimation) family, one per 3-D data sort.

Parameters

----------

vol : array_like, shape (D, H, W)

Input volume (coerced to float64; NaN/Inf rejected).

factor : int or (fz, fy, fx)

Block size per axis, each `>= 1`. The output shape is

`(D//fz, H//fy, W//fx)`; a trailing partial block that cannot fill a

full factor is dropped (deterministic, no edge bias).

mode : {'mean', 'max', 'stride'}

• `'mean'` — average-pool. Band-limits before subsampling (the

anti-aliasing choice); the right default for grey CT / MRI.

• `'max'` — max-pool. Preserves thin bright structures (bone, vessel,

defect voxels) that averaging would wash out.

• `'stride' — plain subsample vol[::fz, ::fy, ::fx]` (fastest,

but aliases — no pre-filter).

Returns

-------

ndarray, shape (D//fz, H//fy, W//fx), float64

The downsampled volume. Spacing scales by the same factor: an input

spacing `(sz, sy, sx) mm becomes (sz*fz, sy*fy, sx*fx)` mm.

Raises

------

ValueError

Non-3-D input, a factor component `< 1` or larger than its axis, or an

unknown *mode* (fail-closed).

背景知識ガイド(この op の手前にある物理・規約)

• depth_sensors — 深度センサの知識 — 測距原理・実機の値・欠測の出方

参考(サンプルデータ・文献)

• サンプルデータカタログ(DL URL / ライセンス) — 2-D は skimage.data(BSD/public)+ 合成、3-D は実データ源(Stanford/PDS 等)の DL URL。

• 演算子の来歴・参考文献 — この op 族の元になった研究/手法の出典。

実行できる例(この op を実際に呼ぶ検証済みサンプル)

• volume_downsampling — py -3.11 examples_3d/volume_downsampling.py

型が繋がる次の op(`voxel` を入力に取れる)

voxel_to_mips · voxel_to_mesh · signed_distance_field · to_points · sobel3d · hessian3d · curvature_maps · edt_jfa

同カテゴリ(`preprocess`)

statistical_outlier_removal · radius_outlier_removal · voxel_grid_downsample · mls_smooth

*Provenance: volops.py — 3D operator registry. この per-op ノートは tools/opdocs.py md が自動生成(手編集しない)。*

volume_downsample — 3D preprocess op

使い方