tb_cylinder_sdf — 2D typed op

Data kinds: pointsvolume

Call: fullseye.apply(img, "tb_cylinder_sdf", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])

tb_cylinder_sdf: input → output

*The figure is the actual output on a synthetic 128×128 input. Left: input, right: output. Point clouds are drawn as a top-down scatter (brightness = z), 1-D series as a line plot, volumes as the maximum-intensity projection along z, videos as the middle frame, complex images as magnitude; return values that are not pictures are shown as the values themselves.*

*Knob a does not change the output (measured: identical at 0.1 / 0.5 / 0.9).*

*Knob b does not change the output (measured: identical at 0.1 / 0.5 / 0.9).*

Stages (the ops that come before → this op, left to right):

tb_cylinder_sdf: stages (docs site)

On other images (synthetic scene / photo / coins. Top row: inputs, bottom row: their outputs. Knobs at default):

tb_cylinder_sdf: other inputs (docs site)

Motion (GIF: frames / views / slices in turn. The still figure is the complete one; the GIF is supplementary):

tb_cylinder_sdf: animation

Usage

> This operator's description has not been translated yet. The original text follows as it is.

有限長の円柱(両端が平らな蓋)の厳密な符号付き距離場(内側負・外側正)。

軸方向の距離 `t と軸からの半径 r に分け、q = (r - radius, |t| - height/2)`

として `outside = ‖max(q, 0)‖inside = min(max(q), 0)sdf = outside + inside`。

これは `box_sdf` と同じ Quilez 流の構成を「(半径, 軸)の 2-D 断面」に適用したもので、

側面・蓋・角(縁)のいずれに対しても真のユークリッド距離になる。

引数と検証(`ValueError`):

• `grid: 最終軸が 3 の float 配列 (..., 3)`。

• `center`: 円柱の中心(端面ではなく重心。要素数 3)。

• `axis`: 軸の向き(要素数 3、零ベクトル・NaN は拒否。長さは自動正規化)。

• `radius: 半径 > 0 相当のスカラ(0` は軸線そのもの、負は拒否)。

• `height: 全長のスカラ(center` から ±height/2。負は拒否)。

返り値: `grid.shape[:-1]` の float64。

使いどころ: **貫通穴は `sdf_subtract(part, cylinder_sdf(...))**(height` を部品より

長くして端面の縁を残さない)。ボス・ピン・シャフトは `sdf_union`。無限長の円柱が

要るなら `height` を十分大きく取る(端面が評価域の外に出れば側面だけが効く)。

2-D 進化レジストリへ橋渡しした 3d の op `cylinder_sdf。実装は同じで、呼び出し規約だけ op(v, a, b) に合わせてある。この op に調整点は無く、ab` も使われない。

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.

Try it in Studio

The program below has been verified to run (same input as the figure). In Studio's help this block becomes buttons that load and run it on the spot.

img_to_points 0.50 0.50
tb_cylinder_sdf 0.50 0.50

▸ Load this pipeline  ·  Load & run

Runnable examples (verified samples that actually call this op)

The examples below call the underlying ledger op cylinder_sdf. This bridge op is the same implementation adapted to the fn(v, a, b) convention, so the behaviour carries over unchanged (only the call form differs).

sdf_csgpy -3.11 examples_3d/sdf_csg.py

Ops the type connects to (they accept volume as input)

identity · vol_gaussian · vol_median · vol_erode · vol_dilate · vol_threshold · vol_reg_dilate · vol_reg_erode

Same category (typed)

tb_points_to_voxel · tb_estimate_point_normals · tb_iss_keypoints · tb_project_points · tb_render_point_depth · tb_statistical_outlier_removal · tb_radius_outlier_removal · tb_voxel_grid_downsample


*Provenance: ops.py — 2D operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*

© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.