Hawk Eye Challenge System has Arrived!

Discussion in 'Rules / Tournament Regulation / Officiating' started by Tactim, Apr 4, 2014.

  1. craigandy

    craigandy Regular Member

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    Thanks. I know nothing of the real workings of these things but that's surprising that every time it takes a week to calibrate and monitored constantly for faulting calibration, to me that doesn't sound like great or consistent a technology. Sounds like they struggle with it.

    I know this isn't how hawkeye does it but in this day in age I thought it would be easy enough to put a few cameras at ground level to catch the moment/time of impact and then one camera on a plan view to sync that time then easily see the impact point from plan view, with some program helping the eyes:D
     
  2. visor

    visor Regular Member

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    ^ I wonder what the frame rate has to be in order to capture down to an accuracy of 3mm when the bird/ball crosses the line at 180mph...
     
  3. Cheung

    Cheung Moderator

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    That would be a lot of money for four courts.
     
  4. craigandy

    craigandy Regular Member

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    I think the answer is 27 027 frames per second.
     
  5. visor

    visor Regular Member

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    Yeah, tennis can afford it, but not badminton.
     
  6. visor

    visor Regular Member

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    Did you just simply type those figures or did you calculate them? :p
     
  7. pcll99

    pcll99 Regular Member

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    u mean 27,027 frames per second?
     
  8. craigandy

    craigandy Regular Member

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    Yeah twenty seven thousand and 27 frames per second:p

    yeah I calculated the amount of time it take the shuttle to go 3mm at 180mph which is 0.000037 seconds. Then I divided 1 by 0.000037 to find out, I was just using logic so it may easily be wrong
     
  9. visor

    visor Regular Member

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    Sounds right. :)

    Then, that's a lot of video data to be collected and analysed from those 6-10 cameras per court.
     
  10. pcll99

    pcll99 Regular Member

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    http://www.popsci.com/technology/article/2013-07/how-accurate-hawk-eye-tennis-ball-caller

    How sharp are Hawk-Eyes really? I'm talking about commercial systems, such as Hawk-Eye and GoalControl, that use cameras to record whether tennis, soccer, cricket and other balls fall in or out of bounds/the goal box/whatever.


    Novak Djokovic relied on Hawk-Eye extensively this weekend to challenge calls during his Wimbledon match with Andy Murray, which Murray won. Those Hawk-Eye replays they show on TV look pretty authoritative, but actually, not all of the system's calls are accurate. Even robot eyes can fail sometimes. The Guardian posted an opinion piece today outlining some of Hawk-Eye's potential weaknesses.


    Because of flaws in cameras, Hawk-Eye can't always be right, but publicly, there's not a lot of information about how big its errors could be. Acting as many companies would, Hawk-Eye doesn't publish the math behind its system in detail. Officials at sports federations probably have an inside scoop, but in a 2008 interview, the head of the International Tennis Federation's technical center, Stuart Miller, didn't seem inclined to let watchers know more about Hawk-Eye's errors. "I'm not sure that the role of Hawk-Eye is public education," he told Nature News.


    Some researchers—and mathematically inclined sports fans—argue that there's a better way. At least one sport does it right, they say. Cricket is transparent about when Hawk-Eye is uncertain and umpires have to use their own judgment. The way that tennis uses Hawk-Eye, on the other hand, hides the technology's uncertainty.
    For a few years now, both researchers and science writers have called for Hawk-Eye replays to show the range of error in the system's reconstruction of plays. That is, they want to see, in that replay cartoon, how far off a Hawk-Eye call could be.


    Why is there error in the first place? As The Guardian explains, cameras can't catch every moment of a ball's flight and fast-flying tennis balls could move pretty far in between frames. Systems like Hawk-Eye depend on mathematical formulas to estimate what actually happened in between.


    Companies' reluctance to publish their formulas helps them protect their intellectual property, but makes it difficult to know what to think about public debates about their errors.


    In 2008, two social scientists from Cardiff University in the U.K. published a paper in which they guessed at how many millimeters off a Hawk-Eye call could be. At the time, Hawk-Eye's inventors disputed the Cardiff analysis, saying that it assumed a pattern of error that the actual Hawk-Eye doesn't follow. The Cardiff folks said (I'm summarizing here; this is not a real quote): "Well, we used a normal distribution and we can't use anything else unless you tell us more about your math." Many things in nature have a normal distribution, which describes the likelihood of any particular outcome in a continuum.


    Hawk-Eye didn't release more information about its math. Instead, its inventors just said its error doesn't fall in a normal distribution. Inventor Paul Hawkins also said that in tests, the system has made the right call every single time.


    For now, the statistical sausage is a secret. Whether it stays that way perhaps depends on how many more fans learn about ball-callers' flaws and say they want to know more.
     
  11. craigandy

    craigandy Regular Member

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    lol
    How do they test if hawkeye is wrong? just with video replay? Is that not just cheaper and better anyway then? And Hawk eye is not 100% anyway so there are still going to be false calls but at massive expense.
     
  12. SigH-Max

    SigH-Max Regular Member

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    The secrecy about the error rate is unacceptable for this price. Is it more accurate than the previous video system? If yes, by how much, and is it worth the extra price?
    Once again, Hawk-Eye's secrecy does not sound good too me, and I think slow-motion video technology is very accurate already, and provides objective feedback.
     
    #32 SigH-Max, Apr 7, 2014
    Last edited: Apr 7, 2014
  13. RedShuttle

    RedShuttle Regular Member

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    Was Hawk-Eye in test or in use at IO? The low success rate (ZERO?) of challenges was highly suspicious.

    I don't know why people trust the cartoon replay of the Hawk-Eye system. It is just animation generated from some parameters which were allegedly collected from the cameras. Some kid may be able to hack the system and control the cartoon with his cell phone from the other side of the earth.

    Just show us the super slow-mo replay and that should be good enough.
     
  14. pcll99

    pcll99 Regular Member

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  15. craigandy

    craigandy Regular Member

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    I only managed to watch one match of Indian open Shixian Wang v Takahashi and there was succesful challenges for starters.
    I agree though hawkeye is not for badminton.
     
  16. craigandy

    craigandy Regular Member

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    [MENTION=57143]visor[/MENTION] did you see that "observe high speed video footage link" within the explanation link pcll99 posted. It was only using 1000fps. Unless that ball is only going about 7mph in real life then I must have over calculated my 27000fps needed for badminton. Any ideas?
     
  17. RedShuttle

    RedShuttle Regular Member

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    The Hawk-Eye does not rely on seeing the ball hitting the line. So the frame-rate is important but not critical. As the description says, it tracks the center of the ball and mathematically determines its trajectory and landing point.

    That's the main reason of my reservation about the Hawk-Eye system. The badminton shuttlecock has a irregular shape and is highly susceptible to air current. Simply tracking the "center" of the shuttlecock is far from being enough to determine the first point of contact of the shuttlecock with the floor.
     
  18. cobalt

    cobalt Moderator

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    Deployment at any ground or arena requires fresh calibration and triangulation, as well as extensive testing. Once set up, it cannot be moved or changed on a whim.

    The main component where the system will require recalibration is in the curve of descent of the shuttlecock. This is very different from that of a tennis ball, or of a cricket ball. The problem is exacerbated by the fact that the rate of descent varies substantially for different speeds of the shuttlecock. The hard smash tends to provide a true and mostly straight flight path but the half-smash or drop can be deceptively sudden in the fall-off once the shuttlecock loses momentum.

    Recalculation based on retracing the flight path from off the cameras can be crucial.

    The drift -which is present, and varies from hour to hour at each and every arena- will also be a crucial factor. Drift varies not only in direction, but also at various heights within the environment. Hawkeye would be concerned only with the effect of drift at ground level, say the last 6 inches above the mat.
     
  19. visor

    visor Regular Member

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    ^ In addition to having to account for the drift, there's also the drop in shuttle speed as the new shuttle's feathers become roughed up even in the midst of a rally.

    But imho, those shots that are slower to drop near the lines (eg. clears) are easier for the line judges to determine, than compared to those faster shots (eg. smashes) that cross the lines at higher speeds.

    We must understand that the higher speed shots are not as affected as much by drift or feather ruffling as the slower speed shots. So imho BWF can still depend on line judges for slow shots... it's the high speed ones that will benefit from either simple video or Hawk Eye instant review.
     
  20. visor

    visor Regular Member

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    [MENTION=86196]craigandy[/MENTION]
    Yes, I saw that. This is where they would say that they're using some secret patented mathematical analysis of the video data from various angles to interpolate the projectile in between frames. :p :)
     

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