elliptic_fourier — SHAPE2D `descriptor` op

• Data kinds: pairs → efdmodel

• Call: import fourierdesc; fourierdesc.elliptic_fourier(points, n_harmonics=10) (or opsshape2d.get("elliptic_fourier"))

Usage

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

閉輪郭の楕円フーリエ係数を Kuhl–Giardina 閉形式で求める。

引数:

points: (N,2) の閉輪郭頂点。閉じていなければ内部で先頭点を末尾に補う。

n_harmonics: 高調波数 N(多いほど細部まで表現)。

返り値: dict

"coeffs": (N,4) 配列。行 n が [a_n, b_n, c_n, d_n]。

"a0", "c0": DC 成分(輪郭の中心オフセット)。

"n_harmonics": N。

再構成 :func:reconstruct は

x(t)=a0+Σ a_n cos(2πnt)+b_n sin(2πnt), y(t)=c0+Σ c_n cos+d_n sin (t∈[0,1))。

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 `efdmodel` as input)

reconstruct · invariants · normalize · descriptor_distance

Same category (`descriptor`)

reconstruct · 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).*

elliptic_fourier — SHAPE2D descriptor op