Over the past few seasons, the hockey media have explained parallax angles over and over and over again, but look, here we are again with the Minnesota Wild fans, photographers and players feeling cheated because this shot (which has to have been taken from at least the area over the blueline) appears to show the puck across the line during that scramble with less than a minute left in Sunday's decisive Game 6.
Really. The Wild players have gotten ahold of the picture that has been circulating Twitter since about two hours after Sunday's 5-4 Dallas Stars win. And that's caused all number of social media headaches.
So once more, with feeling, let's dive into the parallax angle problem.
First of all, here is the picture in question, which was taken by Minnesota-based photographer David Berding. Berding originally posted the photograph on Twitter with a slightly inflammatory caption, and he has since made his Twitter account private, likely due to blowback from people talking about angle issues.
Thankfully, some of the Wild players screenshotted the photo and posted it for everyone to see:
Jarret Stoll (@jarretstoll) April 25, 2016
So a little background before we get into the science of this. Berding uses a remote camera to get shots like this. While the original combination of the far-away shot and zoomed-in picture (which is what Stoll has screenshotted here) is no longer available, you can see Berding's general angle for said remote camera in the first photograph on this linked page.
Extrapolating back to the catwalks, I'd bet this camera is likely somewhere above the blueline, maybe a bit inside of it. It's clearly at an angle toward this goal rather than straight above it.
Which brings us to the concept of parallax angle. According to the always impeccably reliable Wikipedia, parallax is: "a displacement or difference in the apparent position of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines."
You can see their visual representation of it at the Wiki page. In other words, when an object is viewed at an angle different from the known reference, there will be a difference in the apparent position relative to the objects "behind it" because of nothing other than that angle.
If that is as clear as mud, here are two visual references.
The first is my very homemade version from last season, when Matt Duchene was awarded a goal that I was extremely dubious about. The difference in that goal and Sunday's is that in the Duchene goal, the puck disappears under a post and Kari Lehtonen's arm for some very important moments.
The first shot is taken from an angle, in this case low and off to the side. The puck appears to be very much over the "goal line," which is being stood in for by a manual to a keyboard.
That puck looks pretty convincingly over, right? You could make a video review based on that shot alone.
But when you move the camera right over the puck, you end up with this look:
That puck is still clearly over the "goal line" from the overhead angle. And the overhead is what really matters in hockey.
Why is that important? Because most of the ice is clear. There is about an 0.75 inch gap of clear ice between the paint and the surface the pucks rest on. This is because if the paint was too high, it would have to be constantly touched up due to gouging and resurfacing. That gap can make a huge difference for parallax issues, not to mention when a puck may not be resting flat upon the ice surface.
Here's a much more professional visual representation of the parallax problem in hockey, this one from last season's playoffs.
That's pretty darn clear. The only definitive angle for whether or not a puck is over the goal line will be an overhead view. And while goalpost and crossbar-embedded cameras are certainly not perfect (as shown when Devan Dubnyk neatly obscured them all on Antoine Roussel's magically influenced goal in Game 2), they are ideal for a situation like this.
Here is that definitive picture:
THIS CLOSE TO TYING IT pic.twitter.com/GWEk3oyIAe— Pete Blackburn (@PeteBlackburn) April 24, 2016
That picture makes everything hurt inside if you are a Stars fan, and it is also clearly still touching the goal line. The puck appears to be up on edge and against Lehtonen's pad, which brings not only the flat-puck parallax angle, but the deception provided by the asymmetrical shape of the puck as well.
But this is probably my favorite explanation of why this picture is so deceptive. We all know the crossbar parallels the goal line. And yet...
As a few have pointed out, from this angle the crossbar is several feet inside the goal. That is crazy! https://t.co/TvZwAqVhYT— Bob Sturm (@SportsSturm) April 25, 2016
Game, set and match to the parallax angle.