The science behind the score.
A good swing number isn't a verdict handed down from a black box — it's a measurement you can trace back to the movement that produced it. This is how PinPoint Studio reads a swing, the biomechanics it scores against, and the maths that keeps a single number honest.
This page explains the approach we're building. The wrist analyzer produces real output today and is in validation; the full-body kinematics and scoring described here are still being built and checked against a hand-annotated corpus of real swings before any of it is released. Nothing here is a finished, dependable product yet — that's deliberate. See how we earn the numbers →
From frames to a score
To map a swing in milliseconds, each shot runs through a sequence of stages — every one building on the last, from raw pixels up to a coachable number.
- 1
Pose & object detection
Each frame is run through pose models that trace whole-body landmarks — body, hands and fingers — while the club and ball are tracked separately.
- 2
3D fusion & smoothing
Camera angles are triangulated and fused with the IMUs' high-rate motion data, then filtered into a stable 3D skeleton in real metric units — resolving the gaps a single camera can't see.
- 3
Skeleton, scores & faults
Events are anchored on impact, metrics are computed against coaching bands, and faults are ranked by how many points they cost — each with a plain-English drill.
Illustrative — the analysis pipeline, stage by stage.
Full numbers from a single camera
The system adapts to whatever hardware is in the bay — a single calibrated camera with motion sensors is a first-class setup, not a fallback. More kit sharpens the picture.
- 1
One camera + motion sensors
A face-on camera with body and wrist IMUs maps rotation, wrist hinge and the timing of the sequence, while the camera reads posture and tempo.
- 2
A second, down-the-line camera
Resolves depth the single view can't, unlocking club-delivery measures like path, attack angle and a true 3D swing plane.
- 3
A sensor on the club
A light sensor on the shaft gives direct club-head speed and shaft lean without needing the second camera.
Illustrative — sensor placement and a face-on camera.
The power coil: X-factor
Speed in golf isn't arm strength — it's elastic tension stored in the core, which we measure in degrees of separation between the shoulders and hips.
- 1
The backswing coil
The difference in rotation between shoulders and hips at the top. A strong coil separates the two by roughly 40–50°, stretching the core.
- 2
The downswing stretch
As the downswing starts the hips turn first while the shoulders stay coiled, briefly increasing separation — a stretch that acts like a released sling.
- 3
How to use it
A low coil usually means the hips are drifting or over-turning — work on hip stability. A weak stretch means starting the downswing from the ground up, not the upper body.
Illustrative — separation of shoulders and hips, viewed top-down.
The kinematic sequence
Like cracking a whip, speed travels through the body in a specific order. Each segment peaks, then brakes to pass its energy to the next.
- 1
The proper order
Energy peaks bottom to top: hips → chest → lead arm → club. Each segment acts as a pivot, handing speed forward.
- 2
Peak, then brake
To transfer speed a segment has to decelerate rapidly. When the hips brake, that energy surges into the chest; when the chest brakes, it snaps into the arms.
- 3
Out of order
If the shoulders or arms peak before the hips, the swing is "casting" — speed bleeds away, the path changes and slices follow.
Illustrative — peaks fire proximal to distal, in order.
Lead wrist: flexion & extension
The clubface direction is governed by the lead wrist — the one movement read straight from the IMUs and the first analyzer producing real output today.
- 1
Flexion (bowed, palm down)
Bowing the lead wrist rotates the face closed. For a slicer, more flexion helps square or close it.
- 2
Extension (cupped, knuckles up)
Cupping the wrist rotates the face open. Excessive cupping is the most common cause of weak, high slices.
- 3
Radial / ulnar hinge
Cocking the wrist up stores the lag through the downswing; releasing it down snaps the club square at impact.
Illustrative — lead-wrist flexion vs extension and the face.
Sway, thrust & lift
Consistency means turning around a stable spine angle — not swaying side to side or thrusting the hips toward the ball.
- 1
Sway (side to side)
A small shift away from the target in the backswing, then a strong drive back toward the target coming down. Too much either way costs strike.
- 2
Thrust (early extension)
Hips moving toward the ball crowd the arms and force you to stand up out of posture — a big source of blocks and shanks.
- 3
Lift (up and down)
Hold your height through the backswing, then push off the ground into impact — controlled vertical lift is a source of power.
Illustrative — a good drive vs a thrust toward the ball.
One number, no hiding
For a full swing we don't average the metrics — a plain average lets a serious fault hide behind everything you do well. We use a weighted geometric mean, so the weakest link sets the tone.
- 1
Why averages mislead
Five perfect metrics (100) and one critical fault (20) average to a flattering 86 — a score that hides the very thing holding you back.
- 2
The geometric-mean penalty
Multiplying the scores and taking the root lets one low number pull the whole score down. The same swing becomes a realistic 40.
- 3
The coaching idea
You can't paper over a critical mechanical fault by perfecting something else. The score stays honest about what to fix first.
Illustrative — the same swing, two ways of scoring it.
There's no one right wrist
Unlike posture, wrist shape has no single correct answer — great players differ. So instead of scoring you against one ideal, we diagnose which style you're closest to.
- 1
Three archetypes
Your wrist angles at the top and at impact are matched to three patterns: bowed (strong/closed), neutral, or cupped (open).
- 2
A resemblance for each (0–100)
You get an independent match score for every archetype. Your highest one names your pattern; a high score means you're consistent within that style.
- 3
Blended
If your top two scores are within 10 points, you're flagged "blended" — your wrist action is hybrid, and steadying onto one style is usually the goal.
Illustrative — resemblance scores name the swing's style.
A score with a margin
Cameras and sensors live in the real world — shadows, noise and timing jitter are facts of it. Rather than pretend to a false precision, we show an honest range.
- 1
"82 (±9)", not just "82"
The result is an interval — say 73 to 91, centred on 82 — that reflects the real margin of timing and sensor noise.
- 2
Data quality sets the width
Good light, snug straps and two calibrated cameras give a tight band (±3). Poor light or loose straps widen it (±12).
- 3
Noise never costs you
Lower confidence only widens the interval — it never lowers the score. A bad environment shouldn't dent your history.
Illustrative — the score sits inside an honest interval.
Fix one thing, then re-test
The point of all this measurement is a clear next move — not a wall of numbers. The aim is a simple, prioritised loop you can actually practise.
- 1
Know your style first
Check your wrist resemblance. If you're a bowed-wrist player, don't chase neutral or cupped tips — consistency within your own style is the goal.
- 2
Attack the top-ranked fault
Faults are ranked by points lost, so the top one is whatever is holding the score back most. Work on that single thing.
- 3
Drill, then re-capture
Every ranked fault comes with a plain-English drill. Do it, capture a fresh swing, and watch that one metric drift the right way — and the interval tighten as it gets repeatable.
The takeaway: improvement isn't guesswork about "feel" — it's measured movement. Change one thing at a time, let the numbers confirm it, and trust the physics over the urge to overhaul everything at once.
Illustrative — the practice loop, one fault at a time.
Every metric, in plain terms
The walk-through above covered the ideas; this is the complete set of measurements the swing analyzer is built to produce, grouped by what they tell you. Each is read at the swing's key positions (the P1–P8 system, from address to finish) and scored against a reference band at the phase that matters most.
A note on honesty: these are the designed metrics. The lead-wrist set produces real output today and is in validation; the rest are being built on the same capture pipeline. The typical ranges are reference targets drawn from the published biomechanics literature and tour datasets, and stay provisional until our own validation completes. Each card also flags what's needed to measure it:
Rotation & power — the engine
Pelvis rotation
pelvisRotationHow far the hips have turned from address, about the body's vertical axis. The hips lead the downswing, so both their turn at the top and how open they are at impact matter.
Thorax rotation
thoraxRotationHow far the upper torso (the shoulders) has turned versus address. With the pelvis, it sets up the coil that stores power.
X-factor
xFactorThe separation between shoulder turn and hip turn at the top — the stretched-elastic coil. Computed directly as thorax turn minus pelvis turn.
X-factor stretch
xFactorStretchThe extra separation gained in the first instant of the downswing, as the hips fire while the shoulders stay back. A better predictor of speed than the static coil.
Hip internal rotation
hipInternalRotationTrue rotation at the hip joint — the thigh turning relative to the pelvis, per side — which governs how cleanly the lower body clears. Needs a thigh sensor.
Kinematic sequence
kinematicSequenceThe order, timing and size of each segment's peak rotational speed: pelvis → chest → lead arm → club. Each peaks then brakes, passing speed on — the single most coach-trusted signal.
Posture & stability
Spine forward bend
spineForwardBendHow much you stay bent toward the ball, held from address through impact. Standing up early shifts the low point and costs strike.
Spine side bend
spineSideBendTilt of the torso toward the trail side through impact — part of staying behind the ball as the club is delivered.
Secondary axis tilt
secondaryAxisTiltLean of the spine away from the target at impact — the hip-to-shoulder line measured from vertical in the face-on plane.
Pelvis sway
pelvisSwaySide-to-side travel of the hips along the target line — a small shift away from target going back, then a drive toward it coming down.
Pelvis thrust
pelvisThrustMovement of the hips toward the ball. Thrusting early is the classic "early extension" that crowds the arms and forces you upright. It lives along the depth axis a single face-on camera can't see.
Pelvis lift
pelvisLiftVertical rise of the hips. A small, controlled push up into impact adds speed; an uncontrolled one is a fault.
Lead wrist & arm
Bow / cup
leadWristFlexExtFlexion (bowed, palm down) versus extension (cupped) of the lead wrist — the main control of clubface angle, since the back of the lead hand mirrors the face. Carries the highest weight because it drives clubhead speed most.
Hinge (set / lag)
leadWristRadUlnRadial (cocking up) versus ulnar deviation — how the wrist sets the hinge, holds the lag, then releases it. The lateness of the release into impact is the marker of good timing.
Forearm roll
forearmPronationRotation of the lead forearm (pronation/supination) — the "roll" that squares the face through impact, measured as the forearm's axial twist.
Lead arm / elbow
leadArmFlexionHow straight the lead arm stays — the elbow angle from the shoulder, elbow and wrist. The most reliable camera-only metric; a bent, lifting lead elbow late is the "chicken wing".
Trail side & connection
Trail wrist (the "tray")
trailWristFlexExtThe trail wrist's extension that "holds the tray" supporting the club. Flattening it too early is the same throw/flip event the lead wrist shows — used to corroborate the face reading and raise confidence.
Trail set & roll
trailWristRadUlnThe trail-side mirror of the set and the forearm roll. Primarily a cross-check that strengthens confidence in the lead-side findings.
Connection
leadConnectionWhether the lead arm stays connected across the chest rather than lifting away — disconnection at the top, or a bent, splayed lead elbow into impact (chicken wing).
Over-the-top check
trailElbowThe trail elbow should fold to about 90° at the top, then extend in sync with the body. A high "flying" elbow or early extension from the top flags an over-the-top / casting tendency.
Club delivery
You might wonder why these sit here at all when a launch monitor already reads the ball and club. The overlap is deliberate. A launch monitor tells you the outcome; PinPoint tells you what the body did to cause it — and club delivery is where those two worlds meet. In a sound setup the shared numbers should agree, and when they do each set vouches for the other: you get provenance for every reading, and a clean line from a fault in the ball flight back to the move that produced it.
Clubhead speed
clubheadSpeedSpeed of the clubhead at impact, from its 3D path or from grip motion combined with a club sensor.
Club path
clubPathThe horizontal direction the clubhead travels through impact, relative to the target line — in-to-out (+) or out-to-in (−). It lives along the depth axis, so a lone face-on camera can't resolve it honestly.
Attack angle
attackAngleWhether the clubhead is moving down or up at impact — the vertical angle of its travel.
Low point
lowPointAheadInHow far target-side of the ball the clubhead bottoms out its arc, signed in inches. Positive is a low point ahead of the ball — the descending, ball-then-turf strike an iron wants; negative sits behind it, a fat/scoop with an iron but exactly right hitting up on a driver. A delivery number a launch monitor doesn't give you.
Face angle
faceAngleWhere the clubface points at impact — the dominant control of where the ball starts. A true reading needs club/face tracking; until then it's shown only as a clearly-labelled forearm-and-wrist estimate.
Swing plane
swingPlaneThe tilt and direction of the best-fit plane the clubhead travels on through the downswing. Shown as a hand-path proxy when no club is tracked.
Tempo
Backswing time
tempoBackswingHow long the backswing takes, from address to the top — read straight from the swing's phase events.
Tempo ratio
tempoRatioBackswing time divided by downswing time — the rhythm of the swing, and a number that's remarkably consistent among good players.
Measured, not guessed.
Every method here is drawn from the published literature and held against real, hand-annotated swings before it ships. It's an open, inspectable platform — and a prototype under validation, with a first release targeted for late 2026.