balltrack op• Data kinds: points × points → table
• Call: import fullseye as fs; fs.ledger.spin_from_markers(dirs0, dirs1, dt: 'float') -> 'dict' (to call the implementation directly, import balltrack; balltrack.spin_from_markers(dirs0, dirs1, dt: 'float') -> 'dict'; from the registry, opsdrive.get("spin_from_markers"))
Angular velocity vector ω [rad/s] from pairs of marker directions (before (M, 3), after (M, 3), unit vectors).
If M ≥ 2, fit the rotation R by Kabsch (SVD) and compute ω = θ/dt·axis from the rotation angle θ and the axis (feeding directions rotated by a known ω returns it to 1e-9 = gate). If M = 1, return the minimal rotation d₀ → d₁ (axis = d₀ × d₁) ("full" = False): the component about the marker direction is undeterminable in principle, and if the rotation angle between frames is large it also fails as an approximation of the orthogonal component of ω (the marker traces a small circle about the ω axis, which differs from the great circle of the minimal rotation).
Honestly: to get ω from a single marker, make dt small (rotation angle ≪ 1 rad); even then the component about the axis needs another marker. Return value {"omega", "angle", "axis", "R", "full", "rms"}.
• 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_ball_bounce — py -3.11 examples/poc_ball_bounce.py
table as input)course_layout · course_occupancy · course_contains · world_build · world_camera · world_move · lidar_scan · rss_longitudinal_same
balltrack)ball_detect · ball_track · kalman_ca · triangulate_dlt · track_triangulate · bounce_detect · marker_direction · spin_from_marker_sequence
*Provenance: balltrack.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.