hx_split_contours — 2D `halcon_ext` op

• Data kinds: contour → contour

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

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

hx_split_contours: 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.*

Sweeping knob a (0.1 / 0.5 / 0.9, the other knob at its default):

▸ hx_split_contours: knob a sweep (docs site)

*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_split_contours: stages (docs site)

On other images (synthetic scene / photo / coins. Top row: inputs, bottom row: their outputs. Knobs at default):

▸ hx_split_contours: other inputs (docs site)

Usage

Split each contour into segments at its dominant points (RDP; the tolerance eps comes from a).

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

各 contour(点数 3 以上)に Ramer-Douglas-Peucker を掛けて支配点の index を求め、隣り合う支配点の間の部分列

`c[s:e+1]` を新しい contour として並べる(隣り合う線分は端点を共有する)。点数 2 以下の contour はそのまま通す。

• `a → 許容距離 eps = 0.5 + a*5`(0.5〜5.5 画素)。この距離以内の折れは無視されるので、大きいほど線分が

長く少なくなる。

• `b` は未使用。

出力は「線分ごとの contour」であって折れ線の頂点だけではない(元の点は全部残る)。閉じた contour(始点=終点)は

始点から最も遠い点で最初に分割される。線分の本数が角の数の目安になり、`hx_regress_contours` を後段に置くと

各線分の直線性が測れる。

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_split_contours 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

• poc_screw_thread_metrology — py -3.11 examples/poc_screw_thread_metrology.py

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

identity · select_contours · smooth_contours · fit_line_contours · contours_to_region · count_contours · total_length · select_contours_xld

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_split_contours — 2D halcon_ext op