balltrack op• Data kinds: none → signal (an op determined by its arguments alone — it takes no image or data input)
• Call: import fullseye as fs; fs.ledger.marker_direction(marker_uv, center_uv, radius_px, K=None) -> 'np.ndarray' (to call the implementation directly, import balltrack; balltrack.marker_direction(marker_uv, center_uv, radius_px, K=None) -> 'np.ndarray'; from the registry, opsdrive.get("marker_direction"))
Position of a marker in the image (col, row) → direction on the sphere (unit vector in the camera frame, front hemisphere: x right, y up, z toward the viewer).
> The detailed description below is the original text — the summary and the headings are translated.
K (3, 3) を渡すと透視で厳密に解く: 球の角半径 α = atan(半径 px / f) から中心までの距離(半径 1 として 1/sin α)と中心の視線を出し、模様の画素の視線を球面と交差させ、交点の法線を返す。★K が無い形は円板を正射影とみなし、中心を通る視線を z とする系で答える —— 球が光軸から外れていると系ごと回り、球が動く映像では視線の変化がそのまま見かけの回転になる(0.6 m 先を 6 m/s で横切る球は 1 ms で視線が 0.01 rad 回り、1 コマの回転 0.15 rad に 7 % 上乗せされた。2026-09-30、PoC ㉔ の近接カメラ)。K が無ければ従来どおり。
• 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
• poc_table_tennis_bounce — py -3.11 examples/poc_table_tennis_bounce.py
• poc_table_tennis_spin — py -3.11 examples/poc_table_tennis_spin.py
signal as input)flight_vacuum · magnus_lift_coefficient · drag_coefficient_sphere · restitution_from_apexes · restitution_from_intervals · fit_parabola · flight_fit · fit_aero
balltrack)ball_detect · ball_track · kalman_ca · triangulate_dlt · track_triangulate · bounce_detect · spin_from_markers · 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.