hx_dist_ellipse_points — 2D `halcon_ext` op

• Data kinds: contour → feature

• Call: fullseye.apply(img, "hx_dist_ellipse_points", a=0.5, b=0.5) (the 2-D model is one image plus two scalar knobs a,b∈[0,1])

• HALCON equivalent: dist_ellipse_contour_points_xld (the HALCON reference is a useful guide to its meaning and parameters)

hx_dist_ellipse_points: input → output

*The figure is the actual output on a synthetic 128×128 input. Left: input, right: output. Point clouds are drawn as a top-down scatter (brightness = z), 1-D series as a line plot, volumes as the maximum-intensity projection along z, videos as the middle frame, complex images as magnitude; return values that are not pictures are shown as the values themselves.*

*Knob a does not change the output (measured: identical at 0.1 / 0.5 / 0.9).*

*Knob b does not change the output (measured: identical at 0.1 / 0.5 / 0.9).*

Stages (the ops that come before → this op, left to right):

▸ hx_dist_ellipse_points: stages (docs site)

Usage

The maximum distance of the contour points from the fitted ellipse boundary (the per-point distances aggregated by max; a feature).

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

`hx_dist_ellipse_contour と同じ手順(全点をまとめ、重心と共分散の固有分解から半軸 2*sqrt(λ)` の楕円を

当て、各点の正規化半径 `rad を計算)で、|rad - 1| の平均ではなく最大値を 1 で頭打ちした np.float64`

で返す。

• `a, b` は未使用。

• 点が 4 個未満なら 0.0。

最大値なので外れ点 1 つで決まる(雑音に敏感)。値は楕円の正規化座標での差で画素距離ではない。半軸 2σ の

取り方は境界だけの点群に対して sqrt(2) 倍大きいため、完全な楕円輪郭でも約 0.29 の下駄が乗る点は平均版と同じ。

平均版は `hx_dist_ellipse_contour、外れ点を減らすなら前段に smooth_contours_xld`。

Detailed usage guide

• gallery2d_halcon_ext 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.

Try it in Studio

The program below has been verified to run (same input as the figure). In Studio's help this block becomes buttons that load and run it on the spot.

threshold 0.50 0.50
sk_find_contours 0.50 0.50
hx_dist_ellipse_points 0.50 0.50

▸ Load this pipeline · Load & run

Runnable examples (verified samples that actually call this op)

• gallery2d_halcon_ext — py -3.11 examples/gallery2d_halcon_ext.py

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

identity · feature_to_img

Same category (`halcon_ext`)

hx_gen_circle · hx_gen_ellipse · hx_gen_rectangle2 · hx_gen_checker_region · hx_gen_grid_region · hx_gabor · hx_fit_surface1 · hx_fit_surface2

*Provenance: ops.py — 2D operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*

hx_dist_ellipse_points — 2D halcon_ext op