npr op• データ種: image2d → image2d
• 呼び出し: import fullseye as fs; fs.ledger.hatch_field(image, spacing_px=8.0, sigma=2.0, levels=3, cross_deg=90.0) (実装を直接呼ぶなら import printpath; printpath.hatch_field(image, spacing_px=8.0, sigma=2.0, levels=3, cross_deg=90.0)、台帳から引くなら opsprintpath.get("hatch_field"))
絵に沿うクロスハッチ —— 向きは構造テンソルから。
> 以下の詳細説明は原文のままです —— 要約と見出しは訳出済み。
The stroke direction is the local structure orientation (the existing
`structure_tensor_orientation`: strokes run *along* edges, not across them),
and the number of superposed hatch layers comes from the tone — one layer for
a light grey, up to *levels* for a dark one, each rotated by *cross_deg*.
★Why this earns its place: the direction is checkable against a picture
whose orientation is known by construction (a sine grating at 30° must give
strokes at 30°), and the tone is checkable by blurring the result. The usual
NPR routine offers neither.
Returns an `image2d`: 1 = paper, 0 = ink.
Raises `ValueError`: spacing below 2 px; levels below 1; non-positive
sigma; a non-finite or oversized image.
Limits: a single orientation per pixel, so crossings and junctions (where the
structure tensor is isotropic) get an arbitrary but locally smooth direction —
the coherence, not the orientation, is what says whether to trust it.
• 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。
• アルゴリズムの正典(著者・年)と用途は上記ファミリ使い方ガイドに記載。
• poc_beats_fringes_and_screens — py -3.11 examples/poc_beats_fringes_and_screens.py
image2d を入力に取れる)stipple_points_from_image · stipple_energy · stroke_tone_error · halftone_screen · engrave_lines · mosaic_tiles_sites · mosaic_tiles_render · print_layer_defect_map
npr)halftone_screen · halftone_moire_period · engrave_lines · mosaic_tiles_sites · mosaic_tiles_render
*Provenance: printpath.py — PRINTPATH 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)。*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.