volume_downsample — 3D `preprocess` op

• 資料種類:voxel → voxel

• 呼叫: import fullseye as fs; fs.ledger.volume_downsample(vol, factor, mode='mean')(要直接呼叫實作,import volops; volops.volume_downsample(vol, factor, mode='mean');從台帳取用則 ops3d.get("volume_downsample"))

用法

按每軸整數 *factor* 對 `(D, H, W)` 體做區塊池化(資料抽稀)。

> 以下的詳細說明為原文 —— 摘要與標題已翻譯。

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).

背景知識指南(該運算子背後的物理與規範)

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

參考(範例資料・文獻)

• 範例資料目錄(下載 URL / 授權) —— 2-D 用 skimage.data(BSD/公有領域)加合成圖,3-D 給出真實資料源(Stanford/PDS 等)的下載 URL。

• 運算子來歷與參考文獻 —— 該運算子族所依據的研究/方法出處。

可執行的範例(實際呼叫該運算子並已驗證的樣例)

• volume_downsampling — py -3.11 examples_3d/volume_downsampling.py

型別可銜接的下一個運算子(可接受 `voxel` 作為輸入)

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

同類別(`preprocess`)

statistical_outlier_removal · radius_outlier_removal · voxel_grid_downsample · mls_smooth

*Provenance: volops.py — 3D 運算子登記表。本條目由 tools/opdocs.py md 自動產生(請勿手動編輯)。*

volume_downsample — 3D preprocess op

用法