Quick start (60 seconds)
- Mount the phone on a stand — fixed position is essential.
- Pick your mode from the tabs: Bowler End (wides & no-balls), Striker Leg (run-outs & height), Non-Striker (run-outs at bowler's end).
- Tap 📐 Calibrate and follow the prompts. Draw only the lines your match actually uses — tap ⏩ Skip step for any you don't need (no wide line? skip it. no no-ball rule? skip it).
- If cyan dashed lines appear, the tool has detected existing ground markings — tap one to use it and choose which marker it is.
- Tap ARM just before each delivery (or tap the over counter — it counts the ball and arms in one tap).
- Verdicts appear automatically with a snapshot. Everything is saved in the Log.
Camera positions per mode
Bowler End: phone near the bowler's stumps, looking down the pitch. If the bowler delivers from behind/beside the camera, skip the release zone during calibration — the ARM tap then acts as your delivery signal.
Striker Leg: phone side-on at square leg, level with the striker's crease. Best for run-outs, stumpings and full-toss height checks.
Non-Striker: phone side-on to the non-striker's crease (mirror of leg umpire at the bowler's end). Handles run-outs at that end without the bowler blocking the view.
Which lines do I need? (all optional)
- Release zone — where the bowler delivers from. Skip if the bowler is behind the camera.
- No-ball line — only if your match plays a no-ball rule. Two rule types supported in Settings: front-foot crossing (classic) or ball pitching before the line (common turf rule). Skip entirely if your match has no no-ball rule.
- Wide lines — off side, leg side, or both, or neither. Skip what you don't use.
- Bounce line — optional; adds "bounced/full toss" context to every verdict.
- Crease + stumps zone — needed for run-out verdicts in the leg modes.
Skipped lines simply never trigger. Calibrate only what your match rules actually use.
Detected ground markings (cyan lines)
When you start calibration, the tool scans for existing painted/chalked lines on the turf. Detected ones appear as dashed cyan lines. Tap any cyan line and a picker appears asking which marker it is — no-ball line, wide line, crease, or bounce line. This is faster and more accurate than drawing by hand. If your ground markings aren't detected (low contrast, worn paint), just draw manually as normal.
ARM and the delivery window
The tool only issues verdicts during a delivery window — this is what stops casual ball tosses between overs being called as wides.
With a release zone calibrated: tap ARM, then the tool opens the window automatically when it sees motion at the bowler's release point.
Without a release zone (skipped): the ARM tap itself opens the window. Arm as the bowler runs in.
The window closes after a verdict, or automatically after a few seconds.
Reading the verdicts
NO BALL / WIDE — line-crossing detections; the most reliable calls.
RUN OUT / NOT OUT — compares when the stumps were disturbed vs when the crease was crossed; the confidence % reflects the millisecond gap (wider gap = more certain).
VIEW OBSTRUCTED — someone blocked the camera at the key moment; no verdict issued rather than a wrong one.
BOUNCE — informational; feeds "full toss / pitched" context into verdicts.
Every verdict includes a snapshot. Tap a log entry's photo to scrub its clip frame-by-frame.
Exporting the match record
In the Log panel: Data + images (JSON) exports everything machine-readable for records; Match report (HTML) creates a single shareable file with all verdicts and photos — drop it in the team group chat. Everything is erased when the tab closes, so export before leaving.
Troubleshooting
- False triggers: shadows, birds and fielders crossing lines can fire events. Keep zones tight, use the ball-colour calibration in Settings, and only stay armed during deliveries.
- Missed events: ensure good light, the phone hasn't moved since calibration, and the ball is visible against the ground (colour calibration helps).
- Phone heating / lagging: turn off the pose engine in Settings — line calls stay fast.
- Camera stopped after switching apps: return to the tab; it auto-resumes. If not, reload — your calibration can be re-imported if you exported it.
- Bumped the stand: recalibrate. Lines are pixel-locked to the camera position.