Understanding Launch Monitor Data

Commercial launch monitors like TrackMan and Foresight are central tools in modern golf coaching and club fitting. But how well do we understand the data they provide?

A 2017 study by Leach et al. from Loughborough University offers one of the most rigorous independent validations of launch monitor accuracy. The researchers compared both TrackMan and Foresight readings against a high-precision optical tracking system (GOM Inspect), a lab-grade motion capture tool used in aerospace and automotive engineering. Their findings offer critical insights into the strengths, limitations, and differences in how radar and optical systems measure performance.

Measurement Technology: Radar vs Optical

Understanding how each system measures data helps explain why they give different results for certain parameters. TrackMan measures the ball flight using Doppler radar and then derives clubhead parameters, such as dynamic loft and face angle, through impact modelling based on that flight data. By contrast, Foresight uses high‑speed stereoscopic cameras to capture club delivery and initial ball launch separately, with each dataset measured independently rather than one being calculated from the other.

Table 1 Provides an overview of key differences between the two devices.

Important Context: 

The TrackMan Pro IIIe and Foresight GC2+HMT systems evaluated in the study by Leach et al. represent earlier-generation devices. Since publication, both manufacturers have introduced significant hardware and software upgrades, including built-in optical alignment (e.g., GCQuad) and enhanced radar modelling (e.g., TrackMan 4). While the findings remain valuable for understanding measurement architecture and system behavior, direct comparisons with current-generation devices should be made cautiously and with awareness of these developments.

Results: Ball Data Holds Up, Club Data More Variable

The Leach et al. (2017) study tracked over 500 shots from elite male golfers using both systems. 

Tracking Reliability

• TrackMan tracked ball data in 98% of trials and clubhead velocity in 98%, but it only recorded additional clubhead parameters (attack angle, club direction, face angle, and dynamic loft) in 62% of shots. For wedges, this dropped to just 19%.

• Foresight tracked ball data in 90% of shots and clubhead data in 75%, slightly lower than TrackMan, but more consistent across club types (Further context on this difference is discussed later in the limitations section).

Testing Context: These tests were conducted indoors under controlled conditions, with golf balls sandblasted to optimise imaging for the reference optical system. While this ensured precise benchmark measurements, it may have subtly influenced each launch monitor’s performance, particularly in spin rate measurement for Foresight.

Parameter-Specific Insights

• Ball Speed: Both systems performed strongly. Over 80% of values met the ±1 mph research-grade threshold, and systematic bias was negligible.

• Launch Angle: Foresight was particularly accurate, showing an interquartile range of just 0.3°, with 97% of shots within ±1°. TrackMan still performed well at 87%.

• Launch Direction: Foresight showed greater variability and a consistent rightward bias of 1–2°, though both systems exceeded 70% within the ±1° range.

• Spin Rate: TrackMan delivered less variability and over 80% of values within ±50 rpm, although it underestimated spin by ~50 rpm on average. Foresight captured more outliers, possibly affected by glare and imaging constraints.

• Clubhead Speed: Agreement with the optical benchmark was limited. TrackMan met research-grade thresholds on 54% of shots, while Foresight did so on just 29%. TrackMan tended to underestimate speed by ~1 mph, while Foresight overestimated by 2–4 mph, especially with drivers.

• Attack Angle & Club Path: Foresight outperformed TrackMan with 58–67% of values within ±1°, especially on attack angle. TrackMan underestimated attack angle more severely on driver shots (−3.5°) compared to irons (−0.6°).

• Face Angle & Dynamic Loft: TrackMan showed stronger agreement, with 65–66% of values within ±1°. Foresight struggled here, particularly on drivers, with an interquartile range nearing 5°. Dynamic loft showed systematic bias from both systems. TrackMan underestimating by ~1° and Foresight overestimating by up to 5° on some clubs.

These findings reinforce the importance of system-specific context in interpreting launch monitor data, especially for clubhead parameters where variability, club dependency, and measurement timing all play a significant role. Of all the shots included in the sudy by Leach et al, (2017) Foresight successfully recorded ball data in 92% of shots and club data in 84%, while TrackMan recorded ball data in 93% and club data in 91%.

 Its in the details:

• Clubhead Speed: TrackMan underestimated speed relative to the optical benchmark, while Foresight overestimated it by an average of 1.6 mph. TrackMan was within ±1 mph of the GOM system on 54% of shots, while Foresight achieved this on only 29%.

• Ball Speed: Both systems performed well, with TrackMan within ±1 mph on 98% of shots and Foresight on 84%. TrackMan tended to under-report slightly compared to the benchmark.

• Launch Angle: Foresight led slightly here, matching within ±1° in 97% of shots, while TrackMan did so on 87%.

• Launch Direction: Both systems were relatively close, though TrackMan was within ±1° on 76% of shots and Foresight on 71%. However, Foresight showed a consistent rightward directional bias.

• Club Path: Foresight tracked within ±1° on 58% of shots, outperforming TrackMan at 45%. Differences are likely due to variation in marker-based surface tracking versus radar-derived centre-of-mass motion.

• Attack Angle: TrackMan was within ±1° of GOM values on 38% of shots, while Foresight reached 67% — a notable advantage likely due to its high-resolution face-level imaging.

These data points underscore the need to align system choice with the key performance metrics most important to your fitting or coaching context.

Summary from Leach et al. (2017):

• Ball speed and launch angle: Both systems performed well; over 80% of values met “research grade” thresholds.

• Spin rate: TrackMan was more consistent, but typically under-reported spin. Foresight captured more variability, especially on low-spin driver shots (Again, further context on this difference is discussed later in the limitations section).

• Clubhead speed and orientation: Both systems showed significant variability. TrackMan often underestimated speed and calculated orientation. Foresight overestimated speed and showed larger random error in face angle and dynamic loft.

• Launch direction: Foresight showed a consistent 1–2° rightward bias, likely due to target-line alignment error.

Research and Coaching Grade Accuracy

The Leach et al. (2017) study evaluated data accuracy using two important thresholds: Research Grade, defined for academic and high-precision professional environments, where exact measurement is critical and coaching grade which reflects practical tolerances used in coaching and club fitting environments. Research Grade tolerances are provided in the table below and while not explicitly defined in the paper, coaching grade thresholds are inferred to be within ±2.5 mph for speed metrics and ±2° for angular metrics.

The table below shows the percentage of shots from each system that fell within the stricter research-grade thresholds. While both systems showed much higher percentages at the coaching-grade level, these values provide a robust baseline for comparison.

Why These Differences Occur

The Problem of Definitions

One often-overlooked challenge in comparing launch monitor data is the lack of standardised definitions for key parameters. While terms like face angle, dynamic loft, or attack angle are commonly used, their meaning and method of measurement differ between systems like TrackMan and Foresight. These differences are not trivial, small changes in how a parameter is defined or calculated can lead to meaningful differences in the data reported.

For example, TrackMan defines face angle and dynamic loft at the point of maximum compression of the golf ball and calculates these values based on the balls flight. In contrast, Foresight captures these values prior to impact using images of the clubface. This difference in timing can explain why Foresight might report more variability in face angle, especially given how quickly clubface orientation changes during the swing and through impact.

Another example is attack angle and club path. Again, TrackMan calculates these values at the point of maximum conpressions based on ball flight data, while Foresight uses markers placed on the clubhead to determine its motion This introduces not just a definitional difference, but a spatial one: TrackMan's reference point is the club's geometric center, while Foresight's is the area around the marker placement, which may vary slightly from club to club.

In addition, path and angle of attack are not consistent across the front and back of the clubhead. Because the club travels on an arc, the toe and heel can have different vertical and horizontal motions. A point on the back of the club might be descending, while a point on the face could be ascending at the same instant. Foresight typically captures the motion near the clubface surface, while TrackMan bases its estimates on the COG movement, introducing further differences. These intra-club variations become particularly relevant with drivers, where clubhead size exaggerates such effects.

For coaches and fitters, the key takeaway is this: if you're comparing values between systems, or trying to blend data sources, ensure you're not simply comparing different definitions with different methodologies. The differences are subtle but can make a real difference in how data is interpreted and applied.

Spin Measurement

• TrackMan calculates spin using Doppler-based frequency shifts during ball flight. This can underestimate spin, particularly on low-launch, low-spin shots.

• Foresight captures images of the ball as it leaves the face, tracking the rotational movement of dimples. It provides true total spin, but is more prone to error if dimple tracking is disrupted by glare or marker interference. In the Leach study, balls were sandblasted to reduce glare for the GOM optical tracking system. While this was necessary for accurate benchmark measurement, it may have inadvertently biased the results against Foresight, whose system also relies on clear imaging of the ball's surface. This introduces a potential limitation in interpreting the variability in spin rate data from Foresight within the study context.

Club Speed and Orientation

• Club head speed varies significantly depending on where it is measured. Foresight captures reflective markers to measure velocity which varies across the clubface, while TrackMan measures the speed of the geometric center just prior to first touch with the golf ball. Differences between these two systems of up to 4 mph are common.

• Face angle and dynamic loft are especially time-sensitive. Face angle can close by 2.9° per millisecond during impact. In support of this, MacKenzie (2020) reported shaft twisting speeds on the PGA Tour ranging from 650°/s to 2500°/s, suggesting a high rate of angular movement close to impact. Interestingly, this wide variation does not appear to confer a clear advantage and there is no consistent performance benefit associated with a lower closure rate. Foresight’s direct measurement is only as good as its alignment and sticker accuracy; TrackMan’s calculated value is more stable but less granular.

Target Line Alignment

• TrackMan includes laser-assisted alignment and a defined target line.

• Foresight has no built-in target alignment, although in the study by Leach et al., alignment was achieved with a custom-built rig and verified using high-precision optical calibration. Therefore, the observed launch direction bias is unlikely to have resulted from misalignment and may instead reflect limitations in how the Foresight system processes directional data. (Note: later Foresight models do have an integrated optical alignment system using a reflective stick.)

What Can We Take From the Study?

For Fitters

• If you're tracking changes in ball speed, spin rate, or attack angle across multiple shots, TrackMan's modeled averages offer stability.

• Leverage Foresight for short-game and face angle: Its high-speed imaging and impact location data can be extremely helpful for dialling in wedges or analysing gear effect.

• Cross-reference club data carefully: Clubhead speed and dynamic loft may differ across systems. Always consider sticker placement and alignment when interpreting Foresight numbers.

• Know your measurement context: A reported difference in dynamic loft or face angle might say more about how it's measured than what the player is doing.

For Coaches

• Trust ball data trends from both systems: Ball speed, launch angle, and direction are valid and reliable across both.

• Foresight may have the advantage when teaching precision impact control: Especially effective for face/path training if setup is consistent.

• Be wary of reacting to single-shot outliers: It is extremely important to reinforce insights with observations of the ball flight and player feedback before acting on unexpected data.

• When working with players who have data or speak about their impact conditions, find out where the data is derived from (TM, Quad, other)

Future Directions and Implications

This review highlights the importance of knowing how data is generated, not just what is displayed. As launch monitors continue to shape coaching and fitting practices, several developments could strengthen their impact:

• Standardised definitions across manufacturers: Uniform definitions of parameters like dynamic loft or face angle would aid comparison, education, and research.

• Hybrid measurement systems: Combining radar and photometric technologies, or even motion capture with launch monitoring, could offer a more complete picture.

• Fit-for-purpose metrics: Systems could evolve to provide more role-specific outputs. Fore example, club dynamics for fitters vs player feedback for coaches.

• Expanded research on intra-clubhead variability: Investigating how different zones on the clubhead influence reported values could refine interpretation further.

Ultimately, the future lies not just in better sensors—but in better context, communication, and coaching judgment around the data they produce.

Study Limitations and Considerations

While the Leach et al. (2017) and Leach et al. (2023) studies offer valuable insights, it is important to consider a few limitations:

Controlled Environment and Sample Bias

Both studies were conducted in highly controlled indoor environments using elite male golfers. As a result, findings may not fully represent outcomes for recreational players, female athletes, or outdoor conditions where factors like lighting, weather, and swing variability introduce additional complexity.

Ball Surface Modification

To improve image quality for the benchmark optical system (GOM Inspect), the golf balls were sandblasted to reduce surface glare. While this helped ensure reliable reference measurements, it may have introduced unintended bias—especially for Foresight, which relies on imaging the ball's surface to calculate spin. The altered texture could have degraded dimple clarity, potentially increasing Foresight's error margins in spin measurement.

Conversely, TrackMan's radar-based system might have benefited from the reduced reflectivity, resulting in slightly more consistent readings, particularly at high ball speeds.

Club-Specific Tracking Limitations

The study also revealed how differently each system performs depending on the club used. For instance, TrackMan only tracked key club parameters in 19% of shots with a utility wedge, whereas Foresight struggled more with club orientation metrics for drivers. These disparities suggest that no single launch monitor excels across all club types, and system limitations must be interpreted in context.

System Updates Since Publication

It is also worth noting that both TrackMan and Foresight have undergone significant updates since these studies were published. Hardware and software improvements may have addressed some of the tracking gaps, particularly around clubhead data and spin variability. Practitioners should consider the firmware version and model generation when applying these results to modern systems.[LC1] 

Alignment and Marker Placement

Although alignment in the Leach study was achieved with custom calibration rigs, real-world conditions may introduce alignment errors for Foresight, which relies on manual placement and reflective stickers. Similarly, TrackMan’s clubhead estimations, while modeled, can be influenced by ball impact dynamics that vary from player to player.

Practical vs Statistical Significance

Finally, while many differences were statistically significant, the authors note that several were negligible from a practical perspective—highlighting the importance of understanding what level of precision truly matters in a coaching or fitting context.

Final Thoughts

This independent study by Leach et al. (2017) affirms that ball data from both TrackMan and Foresight is valid and suitable for professional use, especially when interpreting trends across multiple shots. However, club data must be interpreted with context. Both systems have strengths and blind spots based on how they acquire measurements.

As launch monitor use becomes more embedded in coaching and club fitting practice, understanding how and where the data comes from is essential. Numbers don’t lie,but they can mislead if we don’t understand their origin.

References

Foresight Sports. (2021). Understanding Ball Launch & Club Data. [PDF]. Retrieved from https://support.foresightsports.com/sites/default/files/downloads/2021/Understanding%20Ball%20Launch%20%20Club%20Data.pdf

Leach, R., Forrester, S., Smith, A., & Roberts, J. (2023). How reliable are measurements of golf impact parameters obtained using commercially available readar and stereoscopic optical launch monitors. Journal of the International Measurement Confederation, 2017-12, Vol.112, p.125-13

MacKenzie, S. J. (2020). An exploration of shaft dynamics during the golf swing and implications for club fitting. In Toms, M. (Ed.), Routledge Handbook of Golf Science (pp. 111–120). Routledge.

TrackMan. (n.d.). TrackMan Golf – How it works. Retrieved July 23, 2025, from https://www.trackman.com/golf