kendama op• Data kinds: image2d → table
• Call: import fullseye as fs; fs.ledger.hole_detect(img, ball_center, ball_radius, *, dark_ratio: 'float' = 0.45, min_sat: 'float' = 0.35, min_chroma: 'float' = 0.1, min_area: 'int' = 3) -> 'dict' (to call the implementation directly, import kendama; kendama.hole_detect(img, ball_center, ball_radius, *, dark_ratio: 'float' = 0.45, min_sat: 'float' = 0.35, min_chroma: 'float' = 0.1, min_area: 'int' = 3) -> 'dict'; from the registry, opsdrive.get("hole_detect"))
Finds the dark disc (the ken-tip hole) in the ball's image: inside the circle with ball center ball_center (col, row) and image radius ball_radius [px], the largest connected component of pixels whose brightness (mean of RGB) is below dark_ratio times the median ball brightness, whose saturation (max − min)/max ≥ min_sat (excludes the gray string), and whose chromaticity (RGB / |RGB|) lies at least min_chroma away from the median chromaticity of the ball (a shaded ball surface only loses brightness while its chromaticity stays the same — picking by brightness alone mistook shadows for the hole; measured and rejected). Returns {"found", "col", "row", "angle" (image angle from the ball center → hole centroid [rad], atan2(Δrow, Δcol)), "offset" (distance / ball_radius: 0 = facing, → 1 = rim), "ellipticity" (minor axis / major axis, from second moments: 1 = a circle seen head-on, → 0 = edge-on), "area" [px]}. If nothing is found, found is False (the rest NaN). Seen head-on, the hole center coincides with the ball center; the further it turns sideways, the closer it moves to the rim and the more it flattens (offset ≈ sin φ, ellipticity ≈ cos φ, φ = angle between the hole axis and the line of sight). ValueError unless img is (H, W, 3) and ball_radius > 0.
• 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_kendama — py -3.11 examples/poc_kendama.py
table as input)course_layout · course_occupancy · course_contains · world_build · world_camera · world_move · lidar_scan · rss_longitudinal_same
kendama)kendama_params · elliptic_k_agm · pendulum_period_exact · pendulum_launch_speed · pendulum_rod_simulate · tether_tension_fixed · tether_slack_angle · swing_up_plan
*Provenance: kendama.py — DRIVE 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.