hx_test_self_intersect — 2D `halcon_ext` op

• Data kinds: contour → feature

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

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

hx_test_self_intersect: 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_test_self_intersect: stages (docs site)

Usage

The fraction of contours that self-intersect (a feature). Non-adjacent segment pairs are tested.

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

各 contour(点数 4 以上)について、隣接しない線分の全対 `(i, i+1) と (j, j+1)(j >= i+2`)を

向き付き面積の符号(ccw 判定)で交差判定し、1 対でも交差する contour の本数を全 contour 数で割った割合を

`np.float64` で返す。始点と終点が一致(距離 1e-6 未満)する閉曲線では、最初の線分と最後の線分の対は隣接扱いで

除外する。

• `a, b` は未使用。

• contour が無ければ 0.0。点数 3 以下の contour は交差なしとして数える。

判定は真に交差する場合のみで、端点が相手の線分上に乗る接触や同一直線上の重なりは検出しない(不等号が厳密)。

計算量は contour ごとに線分数の 2 乗で、点の多い contour では遅い(`hx_split_contours` や

`smooth_contours_xld で点を減らしてから)。hx_gen_parallel_contour` で内側にずらした輪郭の破綻検出に使える。

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_test_self_intersect 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_test_self_intersect — 2D halcon_ext op