The Parallax Problem

No goal play between Calgary and Anaheim

No goal play between Calgary and Anaheim

By Michael Walters

During the Stanley Cup playoffs last year, the Anaheim Ducks and Calgary Flames were involved in a controversial no goal call. In game three with the Ducks leading 3-2, it appeared Sam Bennett had tied the game at three. The original play was ruled as no goal and after a lengthly review, the call on the ice stood. The video below shows the play and multiple replays.

It appeared the puck may have crossed the goal line and should have counted. However, due to the parallax angle or view, the play was ruled as no goal. The parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight. The NHL’s director of hockey ops, Colin Campbell explained in this situation it is caused because the “goal line is painted one-and-a-half inches below the ice. So you can put the puck on the goal line and stand ten feet back and see white ice underneath it.” Here is a video by Sportsnet to help further explain.

This past week, the Ducks found themselves again involved in a similar type of play. In Anaheim’s last game against Pittsburgh, a goal was disallowed because it was ruled Sami Vatanen had not keep the puck in the offensive zone. The play involved the blue line and appeared like the puck might have crossed the blue line. This time the refs ruled the puck had crossed the line and the goal was reversed. Below is the video with several reviews of the play.

Here it appeared the puck may have crossed the blue line and the refs this time ruled that it did. Again the parallax angle could have caused the puck to appear over the line, when it was still partially on top of it. Two Anaheim Ducks team sources did confirm there was an overhead angle that showed the puck had exited the zone.

Conclusion

If a call appears or is probably right, then there is still a problem. In order for the call on ice to be reversed there has to be a definitive or conclusive view. In the first play back in the playoffs last year, there was no definitive view so there was not enough evidence to overturn the original call on the ice of no goal. This is why better technology is needed. The overhead camera angle in the video doesn’t help because of the crossbar is right above the red line blocking part of the view. The league needs to have a camera in the cross bar looking down at the red line. The league has used cameras in the posts before, so using both would really assist in providing definitive views.

In the second play that just happened this week, the original call was the play was onside. An overhead camera angle was reported as showing that the play was in fact offsides, but that camera view wasn’t shown inside the arena or on Fox Sports West. When the refs do have a definitive view of a play, then they need to show it to the audience.

With technology constantly improving, two other solutions could be available. One is the location of the goal line and blue lines below the ice. As explained by the league, the lines are painted one and half inches below the ice surface. It may not be possible, but the league might want to see if there was a way to make the lines closer to the surface.

Another is to use a chip in the puck to better help determine the location of the puck. The league did use technology like this before to display the speed a puck travels on the television. Remember the puck had a blue glow and would display a red streak when shot? Below is a video showing the effect during the 1996 NHL All-Star Game.

Situations caused by the parallax view aren’t going away any time soon. And there will be more controversial plays being reviewed with the newly instituted Coach’s Challenge. There is technology out there to help address this problem and the league needs to look into using it.

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