NHL player tracking system plans to use 'obsolete' optical option

The nature of hockey makes player and puck tracking difficult. Here's where things stand as the NHL plans to begin tracking for the 2019-20 season. Bruce Bennett/Getty Images

Player and puck tracking in the National Hockey League, which is scheduled to arrive for the 2019-20 season, has a few objectives. It will create new and more accurate statistics. It will provide unprecedented ways for teams and players to evaluate performances. It will add hundreds of new wagering options to the sportsbooks, from betting on shot location to the speed of players, in an effort to attract new fans through legalized gambling.

Mathieu Schneider, NHLPA special assistant to the executive director, also sees it as a narrative device. "It will help tell stories of the great athletes that we have in the NHL," he said during January's tracking test at the NHL All-Star Game in San Jose, California.

But the system the league favors -- ultra-wideband radio frequencies, used to track wearable technology on the players and inside the puck -- apparently can't tell the full story. Which is why the NHL plans to use a hybrid system of both sensor tracking and optical tracking, which relies on cameras around the rink, beginning next season.

"We're convinced that the best solution for us is a two-system tracking system: a sensor-based system that will give us X-Y-Z coordinates for the players and the pucks, and an optical system that will give stick position, body position and limb recognition that we can add to the X-Y and X-Y-Z coordinates to get the full data," said David Lehanski, the NHL's senior vice president of business development.

"If the tests go well, we'll be looking to add that optical component at some time next season. It may not be exactly aligned with the rollout of the [sensor] system, but ideally at some point next season."

Lehanski said the NHL has been investigating optical tracking systems for the past two years as a way to complement the sensor tracking. The league tested one system at the NHL All-Star Game in Tampa, Florida, in 2018. It's currently testing an optical system in four arenas, working with Sportlogiq and using home teams the league felt would play into the postseason to maximize the opportunities to try it out.

The NHL has heavily promoted its planned use of the sensor-based system, including an elaborate presentation at the NHL All-Star Game in January. But the optical component of its player and puck tracking system hasn't received the same marketing push. Perhaps that's because a camera-based system for hockey has been a controversial option. While it has been used to great effect in sports like tennis to track the path of the ball, the amount of obstructed views in a typical NHL game renders it ineffective.

"The blind spot in optical tracking is that objects collide. You have to wait for those things to disengage before you sort it out," a source who works in sports tracking technology told ESPN, adding that a successful optical-only tracking system "hasn't been cracked yet."

The NHL actually flirted with the idea of an optical-only tracking system in the past few years, before rejecting it in favor of the sensor system. "The puck moves really fast," Lehanski said earlier this year. "It's constantly changing, and moving behind other objects -- skates and sticks -- which makes optical obsolete."

But not completely obsolete, it seems. When paired with the league's sensor tracking, which uses equipment from Germany's Fraunhofer Institute and tech from Jogmo World Corp, the NHL decided there was a place for optical tracking in its plans. The sensors will tell us where the puck is; in theory, the optical tracking will tell us when a player actually possesses it. The end result, the NHL says it hopes, will be a complete digital picture of what's happening on the ice.

"If you just have coordinates for the players, you'll know when a puck is close to a player, but you won't know the exact moment that it hits their stick. If you add the optical tracking, you can see when that happens. When you add that to the X-Y, you'll know with a high degree of accuracy when a puck is on a player's stick," Lehanski said.

Accuracy is going to be paramount in player tracking, which is why Lehanski and his team are also working on a way to validate the data collected in the system's embryonic stages.

"We need to build a pretty comprehensive data repository. We need to validate it for accuracy, for consistency from arena to arena, and have it all in one central location," said Lehanski, adding that the location of that repository would be in the NHL offices.

The data has to be verified, and has to show levels of accuracy that aren't possible when compared to the human beings currently tracking it. The equipment needs to be in place to collect it, too. The NHL has taken three dimensional laser scans of all of its arenas to develop virtualizations of their layouts, so Fraunhoffer and Jogmo can determine where the optimal positions for the sensors should be. That scanning took a few weeks, Lehanski said, and now installation will "run through a good part of the offseason."

There are 14 antennas around the arena. There's a sensor in the shoulder pads of players being tracked 200 times per second, and a sensor inside the puck that can be tracked 2,000 times per second.

The process extends to the sensors themselves, as well. The NHL has prototypes that are significantly smaller than the ones used earlier this season -- while those were the size of an Oreo cookie, these newer and lighter ones are around the dimensions of a quarter, although double the thickness.

Then there's the puck.

Is the puck OK?

"The puck is good," Lehanski said. "We're making some tweaks to it, trying to totally optimize the playability of it. Little things that we're doing with it."

The puck remains the most contentious part of these equation for players. Some claimed they could feel a difference when using it during announced tests at Vegas Golden Knights games, although the league maintains the pucks they've used were "in line with the specs" as far as size and weight.

In its last tests, the league rounded the edges of the puck a bit more, and will continue to tweak them.

"We will always be constantly thinking about a better way to do it, to optimize it," said Lehanski, adding that it could even extend back to the way the new pucks are made with injection molding.

At this stage, it's trial, error and adjustment. Sometimes that can mean rounding the edges on a puck. Sometimes that can mean the reintroduction of a previously rejected form of tracking to present the fullest data picture possible. The NHL says it believes that player tracking can revolutionize the way we think about hockey; Lehanski and his team say they believe that getting there requires an open mind.

"I drive people crazy because I'm always taking people on field trips to see different technology," he said. "Every couple of months, we hear something a little bit new."

When it comes to optical player tracking, what's old is new again.