arc — ANNOTATE `shape` op

• Data kinds: image2d → image2d

• Call: import fullseye as fs; fs.ledger.arc(img, center, radius, start_deg, end_deg, color='neutral', width=2, alpha=1.0, scheme='okabe_ito') (to call the implementation directly, import annotate; annotate.arc(img, center, radius, start_deg, end_deg, color='neutral', width=2, alpha=1.0, scheme='okabe_ito'); from the registry, opsannotate.get("arc"))

Usage

A circular arc. Angles are in degrees, clockwise from the screen x-axis (because row points down).

> The detailed description below is the original text — the summary and the headings are translated.

Raises

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ValueError

radius が非正、角度が非有限、start == end、alpha が [0,1] の外。

描画: 中心からの距離 `d が |d - radius| <= max(0.6, width/2)` で、かつ

画素の方位角が `start_deg から時計回りに (end_deg - start_deg) mod 360` の

範囲にある画素を塗る(アンチエイリアス無し)。方位角は `atan2(y - cy, x - cx)`

で、0 度 = 右(+x)、90 度 = 下(+y)、時計回りが正。

• `center: (x, y)`、x = 列・y = 行。画像外でもよい(はみ出しは切れるだけ)。

• `radius`: 正 [px]。

• `start_deg, end_deg: 度。start から時計回りに end` まで描く。

差が 360 の倍数(`end - start` が 0 でなく 360 など)は全周。

`start == end は「長さ 0」なので ValueError`。

• `width: 線幅 [px]。max(0.6, width/2)` を半幅にするので 1 px 未満でも

途切れない。

• `img / color / alpha / scheme の扱いは rounded_rect` と同じ

(float64 複製、`[0, 1]`、役割名か RGB)。

• 返り値: 入力と同形の float64。

角度を書き込む学術図の作法は `annotate_angle` が引き出し文字まで面倒を見る。

Detailed usage guide

• figure_annotation family guide

Background guides (the physics and conventions behind this op)

• dataset_conventions — 学習データセット規約の知識 — COCO / YOLO / VOC と外観検査での落とし穴

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.

• The canonical algorithm (author, year) and its uses are named in the family usage guide above.

Runnable examples (verified samples that actually call this op)

• annotate_gallery — py -3.11 examples/annotate_gallery.py

• poc_weld_radiograph_porosity — py -3.11 examples/poc_weld_radiograph_porosity.py

Ops the type connects to (they accept `image2d` as input)

text_box · arrow · leader_line · label_points · crosshair · legend_box · color_bar · scale_bar

Same category (`shape`)

rounded_rect · filled_polygon · ellipse

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

arc — ANNOTATE shape op