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Case Studies

STRI Trueness Meter™

Category: golf

In 2006, STRI agronomists and sports research scientists joined forces to develop a device that accurately measured the trueness and smoothness of golf greens.

They produced the innovative STRI Trueness Meter, which assessed the amount of deviation of a rolling golf ball and collected data, which could be analysed and used to inform golf course management.



Ball roll characteristics of a putting surfaces is critical. The roll of a ball should be smooth and true and not negatively influenced by the immediate turf surface. The objective is to reward the skill of the golfer who can read the topography of the green and accurately putt the ball. It is highly undesirable for the golf ball to deviate from its line of roll. As a result, non-topographic features such as pitch marks, earthworm casts, disease scars or even textural differences in the grass species growing on a golf green can influence ball roll.


The STRI Trueness Meter™


There are devices that allow us to roll golf balls on the turf surface and measure the distance rolled to provide an indication of frictional properties. What has been missing has been a way to easily and accurately measure the amount of deviation a golf ball experiences as it rolls across a surface. The greater the degree of deviation, the greater the probability that the ball will be deflected off its intended line and miss the hole. To be able to objectively measure how smooth and true ball roll is on is any given putting surface, means that targeted maintenance advice can be given to improve this important aspect of surface performance.





The challenge was to develop a device that was accurate, robust and easy to use, as the testing would be carried out on in-play greens.  The initial aims of the research were to:

  • Evaluate the principle of measuring the smoothness (vertical deviation) and trueness (lateral deviation) using this approach.
  • Investigate the optimum configuration of the machine, in terms of wheel size, the distance between the wheels and whether the wheels should be rigidly fixed to the frame of the unit or mounted on rotatable bogies.
  • Assess the speed at which the unit should be pushed over the putting surface.
  • Determine the best index for measuring smoothness and trueness.




The initial testing took place indoors on surfaces of increasing roughness during late 2006 and early 2007. This proved that the prototype could detect differences between surfaces of varying roughness and provided initial validation of the measurement principle. Testing on contrasting turf surfaces was carried out during 2007. These results helped to refine the design of the prototype with regard to its configuration.



The prototype was further refined to allow a more automated approach to capturing the data and processing the vast quantities of it (50,000 readings per 10m run).

Final testing with the prototype took place during 2008 and 2009 on a wide range of golf courses. The values measured indicated that the unit was capable of detecting both large and subtle differences in putting surfaces. This provided the final validation of the measurement process, which was sensitive enough to detect features such as disease scars, pitchmarks, and patches of annual meadow-grass.


The Results

The STRI Trueness Meter™ was introduced into routine agronomic visits as part of the STRI Programme.

The ability to objectively measure how a ball reacts to a putting surface, not only from a green speed point of view, but also in terms of smoothness and trueness of ball roll, has been the last piece of the jigsaw puzzle in understanding what makes a high quality putting surface.

It has also allowed us to better monitor the effect of golf green maintenance practices on turf quality and when combined with surface firmness and green speed, we now have a much better understanding of the playing quality of golf greens.