hatch_field — PRINTPATH `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"))

使い方

Cross-hatching that follows the picture — direction from the structure tensor.

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.

詳しい使い方ガイド

• printpath ファミリガイド

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。

• 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。

実行できる例(この op を実際に呼ぶ検証済みサンプル)

• poc_beats_fringes_and_screens — py -3.11 examples/poc_beats_fringes_and_screens.py

型が繋がる次の op(`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

同カテゴリ(`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)。*

hatch_field — PRINTPATH npr op

使い方