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Five matches into TGL’s inaugural season, a few key storylines have emerged. Perhaps the most interesting of all has to do with the league’s technology. The nature of a made-for-TV, indoor golf league means the tech itself is perhaps more important than any one player using it.
So, ahead of TGL’s first-ever tripleheader of matches last Monday, we interviewed TGL’s tech chief Andrew Macaulay to answer all the questions fans have been asking: about how it works, about its accuracy, and about some controversial shots that have golf fans talking.
Editor’s note: This interview has been lightly edited for clarity and brevity.
Golf Digest: TGL has a lot of tech stacked on top of each other, so that’s probably the best place to start. How does it all work?
Andrew Macaulay: A lot of people out there, through no fault of their own, don’t understand how we built it.
It starts with how golfers choose their shot. They use the digital caddy, which is part of the customized version of Full Swing’s simulator product. The digital caddy, the game you play, the course you see, that’s all Full Swing software. Once they select their shot, the Full Swing software tells them which of the six boxes to hit from. The player then gets up there, does their pre-shot routine, steps into the box and hits their shot.
GD: What happens next?
AM: After players hit their shot, the ball flies towards the screen. We’re tracking that golf ball in a couple of different ways, but the primary way is using TopTracer’s tracking technology. SoFi has 8 TopTracer optical camera systems working in pairs, so four tracking systems. For most shots, players hit into a screen 35 yards away. TopTracer sees the first 35 yards of the ball’s flight and projects the rest of the shot’s arc.
Cliff Hawkins/TGL
GD: So TopTracer is capturing what is happening to the golf ball?
AM: Correct. Full Swing captures club speed and other data in parallel, but TopTracer creates a three-dimensional set of coordinates of where the golf ball is traveling along its arc. TopTracer gives that to Full Swing. When it intersects with land, TopTracer is done. Then Full Swing’s logic takes over to say “you’ve hit the fairway, or it hit a slope, so it’s going to bounce left” or “you’ve hit the rough, so it’s going to bounce and stop quickly like rough does.”
GD: Why was 35 yards from the back tee to the screen the sweet spot? Why not more or less?
AM: Thirty-five yards of ball flight into the screen gives us more than enough data to be a lot more accurate than if the screen were just a few yards in front. More data in means better answers out, at a basic level. … So 35 yards of ball flight to the screen … the player [can] see if it’s going high, low, left, right, starting to curve, or if they pulled it left and it’s a pull fade. … TopTracer is optical tracking, not radar. … That’s the ultimate answer on why that number versus some smaller or further away number—it gives us enough information to be ultra-confident in the accuracy of the extrapolation of the remaining flight.
GD: It’s obviously a crowded, competitive space with lots of ball-tracking technologies out there. How did you land on this combination?
AM: My background includes 10 years at Topgolf as CTO, looking at all kinds of golf tracking technologies. There was a lot of existing knowledge combined with R&D and trial. When you look at what we were trying to achieve at TGL—where players can move around, and the ball can be dropped anywhere within six different boxes by the player to hit from any lie—you start to cross certain golf tracking technologies off the list. We wouldn’t be able to do that if players have to place their ball within a perfectly-aligned, 12-by-12 inch hotspot.
Carmen Mandato/TGL
GD: Foresight is considered by many the gold standard for capturing spin rate, which can be notoriously tricky for any system to capture accurately. Some fans ask: Why not go with them?
AM: If you want to know the spin at the moment of impact of the ball, [Foresight’s] GC Quad has a margin of error, but it is the best out there. We don’t use it in competition, but we’ve hit thousands and thousands of shots in testing with other technologies to compare and help us dial in.
GD: A big question a lot of golf fans have is how do you ensure TGL’s system is accurate?
AM: TopTracer is looking at the actual ball flight. We’re observing what the ball is actually doing and extrapolating from that. The amount of spin you put on the ball certainly affects that. So I get a spin number there. I’m also getting the launch parameters. We also have eight Full Swing KIT launch monitors, which gives me club speed and another spin calculation to leverage. I wanted redundancy because every tech out there, whether they admit it or not, has their own margin of error. They’re really good at some things and less good at others. I feel good that we’ve got multiple inputs on the spin number to help us be accurate. I’m very confident in its overall accuracy.
[Editor’s note: On the second hole of TGL’s second match between Jupiter Links and Boston Golf, Tiger Woods had 101 yards to the flag and hit a wedge that appeared to travel 131 yards and into the water long of the green]
GD: The elephant in the room here is that Tiger wedge shot. A lot of golf fans say that Tiger doesn’t miss wedge shots like that. What is your response?
AM: That was the shot that he hit, but I do want to clarify something: The shot he was trying to hit was 101 yards. The total distance of the shot he hit was 131 yards. Everyone’s been focused on that 30-yard difference and saying, ‘Tiger Woods doesn’t do that,’ right? Unfortunately, there was a graphical error on the screen. If you watch the shot itself, the ball landed long of the green onto a severe downslope and took a big kick forward into the water. You can see it for yourself, and we have the data on it. The actual distance the ball carried of that shot was 119 yards. But because the ball ended in a penalty hazard, the system displayed the total distance number [131 yards] twice.
[Editor’s note: In the Feb. 5 match, Tommy Fleetwood appeared to stripe an iron shot, but the screen made it look like the ball didn’t go anywhere. Joked teammate Justin Rose, “Tommy, you hit it too flush.” Officials ruled the shot invalid and Fleetwood got to. hit again.]
GD: The Tommy Fleetwood shot, which we all know was an obvious misread. As TGL’s tech guy, what’s your explanation for that?
AM: We pretty quickly determined that was just invalid and why. In this case, Tommy had an amazing divot. It was beautifully formed. It flew 20 yards along the arc of a golf ball. Since TopTracer is looking for things flying through the air in that direction, it tracked both the golf ball and the divot. The error was choosing the wrong object. There’s tons of logic in there to prevent that from happening both on TV and in our world. Unfortunately it got by that. But we had the rule in place that an obvious invalid reading gets a re-hit with no penalty. That was a quick decision and play moved on. Everyone seemed fine with it. And of course, in the background, we’re taking this particular example of tracking the wrong thing and feeding that back. The system’s learning from that too. It’ll be even rarer from now on.
GD: Finally, what’s one thing you want every golf fan to know about TGL’s tech?
AM: TGL is the most technologically innovative golf league in the world. We have lots of different people, from golf nerds to casual fans, watching, and we’re really excited about it. I want them to know that they should have ultimate confidence in the accuracy of this. It’s as realistic as it can possibly be made. There will be imperfections occasionally, but it is everything I want it to be.
Main Image: Cliff Hawkins/TGL
