contour op• Data kinds: mask → table
• Call: import fullseye as fs; fs.ledger.level_set_reinit(phi, *, method: 'str' = 'sussman', n_iter: 'int' = 100, dt: 'float' = 0.5, band: 'float' = 3.0) -> 'Dict[str, object]' (to call the implementation directly, import segcontour; segcontour.level_set_reinit(phi, *, method: 'str' = 'sussman', n_iter: 'int' = 100, dt: 'float' = 0.5, band: 'float' = 3.0) -> 'Dict[str, object]'; from the registry, opssegmentation.get("level_set_reinit"))
Turns φ (inside where φ < 0) into the signed distance function of the same zero level set (level_set_reinit).
method="sussman" = φ_τ + S(φ0)(|∇φ| − 1) = 0 (Sussman–Smereka–Osher 1994) with Godunov upwind differences for n_iter iterations (step dt ≤ 0.5). Grid points touching the interface (sign changes in the 4-neighbourhood) get the subcell fix of Russo–Smereka 2000:
they relax towards D = φ0 / Δφ0 (Δφ0 = the maximum of the central-difference gradient magnitude and the one-sided differences), so the zero level set does not move. method="edt" = signed distance built by distance transform from the mask φ < 0 (2nd implementation; the zero level set is quantised midway between pixel centres and moves by up to half a pixel). Passing a bool mask uses the edt signed distance as φ0.
Returns: phi, grad (10/50/90 % points of |∇φ| where |φ| ≤ band, and the pixel count), grad_before (same, for the input), zero_hausdorff (Hausdorff distance between the zero level sets before and after, pixels), method, n_iter.
• halcon_segmentation family guide
• active_contours_and_level_sets — Variational and active contours, level sets — which contour stops where, and what it guarantees
• 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.
• poc_active_contours — py -3.11 examples/poc_active_contours.py
table as input)contour)snake_evolve · gvf_field · chan_vese_energy · chan_vese_evolve · morph_chan_vese · morph_geodesic_ac · edge_stop_g · drle_evolve
*Provenance: segcontour.py — SEGMENTATION operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.