Why the same wedge shot can stop on one virtual green and run through another

Imagine a wedge landing six feet short of the flag and settling pin high. Change the virtual turf and the same shot can finish well past the hole. To tell whether the difference came from the launch monitor or the simulator, watch where the ball lands and what it does next.

What the launch monitor sends

GSPro’s Open Connect specification illustrates what a simulator can receive: ball speed, horizontal and vertical launch angles, spin rate and spin axis. The interface can also accept carry distance and club data. What’s directly measured, estimated or unavailable depends on your monitor and setup.

Ball speed and the two launch angles describe how the ball leaves the club. Spin rate describes how fast it rotates, and spin axis describes how that rotation is tilted. Those values give the simulator its starting conditions. Indoors, where a screen stops the ball after a short flight, the landing point and rollout are modeled.

What the simulator does with the shot

Carry is the distance to the first landing. First bounce describes how the ball comes back off the surface. Rollout is how far it travels after landing. Two shots can carry the same distance and leave very different putts.

The ball arrives with a particular speed, angle and spin. The slope and surface at the landing point help determine what happens next. Researchers who recorded more than a thousand golf ball bounces found that a simple bounce model didn’t capture all the behavior they observed. A sim’s turf setting gives you a surface to practice on, and you can compare its response with the greens you play outside.

GSPro’s Physics 2.0 beta notes say its original model was tuned on firm, links-style turf. The company added a different response after players asked for conditions closer to those they encounter on many North American courses. In a later beta covered by The Perfect Lie, Joe Lagowski tried separate turf profiles and paid particular attention to the first hop on soft bentgrass.

How to tell where the difference came from

Choose one flat practice green and one target. Keep wind, elevation, green speed and other realism settings fixed. Record the launch data for a low chip, a pitch and a full wedge. If your setup can replay the same launch data, replay each shot across the available turf profiles. If you’re hitting live balls, compare shots with similar launch numbers and expect some variation.

For each shot, mark where it lands, where it takes its second bounce and where it finishes. Write down the sim build and turf setting. Change one setting at a time. A different landing point sends you back to the launch inputs or flight settings. A similar landing point with a different hop or finish tells you to look at the ground response.

Take that habit to the course. Pick a landing spot before you choose the shot, then watch how the first few balls behave around the practice green. Use what you see to adjust the next landing spot.