xg_orientation — 2D `xldgeom` op

• Data kinds: contour → feature

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

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

xg_orientation: 入力 → 出力

*The figure is the real output on a synthetic 128×128 input. Left: input, right: output (a non-image return value is shown as the value itself).*

Usage

Principal-axis orientation in degrees, folded to [0,180) and /180 scaled.

Angle is measured from the +x (column) axis; multiply the result by 180 to

recover degrees. Line orientation is defined mod 180, so a line at theta and

theta+180 map to the same value.

Discontinuity (inherent, documented): a line orientation lives on a circle of

180 degrees, and this op unrolls it to [0, 1), so the wrap sits at HORIZONTAL —

a line tilted +0.001 deg returns ~0.0 while -0.001 deg returns ~0.9999. Any

single-scalar unrolling has a seam somewhere; callers that need continuity

across horizontal should compare orientations on the doubled angle

(cos 2*theta, sin 2*theta) or take the difference mod 1. The closing point of a

closed contour is not double-counted in the PCA.

Detailed usage guide

• gallery2d_geometry 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
xg_orientation 0.50 0.50

▸ Load this pipeline · Load & run

Runnable examples (verified samples that actually call this op)

• gallery2d_geometry — py -3.11 examples/gallery2d_geometry.py

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

identity

Same category (`xldgeom`)

xg_moments · xg_area_center · xg_eccentricity · xg_elliptic_axis · xg_height_width_ratio · xg_regress_contours · xg_clip_contours · xg_gen_polygons

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

xg_orientation — 2D xldgeom op