reconstruct — SHAPE2D descriptor op

• Data kinds: efdmodel → pairs

• Call: import fullseye as fs; fs.ledger.reconstruct(model, n_points=300, n_harmonics=None) (to call the implementation directly, import fourierdesc; fourierdesc.reconstruct(model, n_points=300, n_harmonics=None); from the registry, opsshape2d.get("reconstruct"))

Usage

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

EFD 係数から輪郭を再構成する((M,2))。

n_harmonics を係数数より小さくすると 高調波を打ち切って平滑化 される

(低次だけ残すほど丸くなる)。

式: `t = linspace(0, 1, n_points, endpoint=False)` について

`x(t) = a0 + Σ a_n cos(2πnt) + b_n sin(2πnt)`、

`y(t) = c0 + Σ c_n cos(2πnt) + d_n sin(2πnt)(n = 1..N`)。

• `model: elliptic_fourier の返り値(coeffs (N, 4)、a0、c0`)。

`normalize` を通した係数を渡せば正準ポーズ(第 1 高調波で整列)の輪郭が

出る。dict の検証はしない(キー欠落は `KeyError`)。

• `n_points: 出力点数 M(int` に切る)。等パラメータ間隔で、弧長

等間隔ではない。`endpoint=False` なので末尾点は先頭点と一致しない

(閉じた多角形にするなら先頭点を末尾に足す)。0 なら空の `(0, 2)`。

• `n_harmonics: 使う高調波数。None で全部、N より大きい値は N` に

切り詰め、0 以下なら DC だけ(全点が中心 `(a0, c0)`)。

• 返り値: `(M, 2) float64。座標の並び((x, y) か (row, col)`)は

`elliptic_fourier に渡した並びをそのまま引き継ぐ。t = 0` は元輪郭の

始点に対応する。

輪郭を係数化せずに滑らかにするだけなら `fourier_smooth`。係数どうしの

比較は `invariants / descriptor_distance`。

Detailed usage guide

• shape_description_2d family guide

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)

• contour_fourier — py -3.11 examples/contour_fourier.py

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

elliptic_fourier · fourier_smooth · add_frame_corners · warp_tps_image · warp_piecewise_affine · morph · morph_sequence

Same category (descriptor)

elliptic_fourier · invariants · normalize · descriptor_distance · fourier_smooth · from_xld

*Provenance: fourierdesc.py — SHAPE2D 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.