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  1. #35
    Regular Member craigandy's Avatar
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    Quote Originally Posted by RedShuttle View Post
    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.
    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.

  2. #36
    Regular Member craigandy's Avatar
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    @visor 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?

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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.

  4. #38
    Moderator cobalt's Avatar
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    Quote Originally Posted by Oldhand View Post
    In India and England, the systems are available locally, ready to use when needed.
    That's because the system is already being used extensively in cricket and tennis (and newly, football).

    Although Hawkeye is based in the UK, it's now owned by Sony.
    As such, the systems are directly compatible with Sony's broadcast cameras.

    Countries where Hawkeye doesn't have a local presence will need to pay the full amount if they want to use the 'Decision Review System'. For example, if the Singapore Open or the Indonesia Open wants to use it, the extra cost will be a heavy burden on the organisers.
    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.

  5. #39
    Regular Member visor's Avatar
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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.

  6. #40
    Regular Member visor's Avatar
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    Quote Originally Posted by craigandy View Post
    @visor 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?
    @craigandy
    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.

  7. #41
    Regular Member craigandy's Avatar
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    Quote Originally Posted by RedShuttle View Post
    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.
    They will just take the centre of the cork no? The cork is all they have to concerned about with regards to contact point

  8. #42
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    I think the main reason for implementing the Hawk-eye system is to take line judge partiality out of the equation. As long as the system perform at a relatively consistent level, tolerance of 1mm or 5mm is not as important, since both sides would be subjected to the same standard! Whether it is a good value for the cost is another matter!

  9. #43
    Regular Member craigandy's Avatar
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    Well that's one way to look at it, another way - If it has tolerance of 5mm then it is not really solving the problem that they want to solve, which is when a player decides to question a possible bad call BWF wants an actual truthful answer or what's the point?
    What Hawkeye does offer is a is a very expensive but great side show but not a solution, unless the intent is just to make the sport more exciting for fans.

  10. #44
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    Quote Originally Posted by craigandy View Post
    They will just take the centre of the cork no? The cork is all they have to concerned about with regards to contact point
    No. It's the whole shuttle. Bottom or side of the cork, or the feathers.

    Depending on the position of the shuttlecock in flight, any part may touch the floor first.

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    From the BWF news release, they are more interested in leveraging the Hawk-Eye brand appeal.

    They seem to think the spending in Hawk-Eye will translate to fan appeal and bring people to badminton.

  12. #46
    Regular Member craigandy's Avatar
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    Quote Originally Posted by RedShuttle View Post
    No. It's the whole shuttle. Bottom or side of the cork, or the feathers.

    Depending on the position of the shuttlecock in flight, any part may touch the floor first.
    No I'm pretty sure it's not possible for the initial contact point to be anything but the rounded area on the cork. Unless It is heavily tumbled but even then it's never happened. If you do the maths you will find out it is not possible. The space is too small for it to be possible if the drag difference were the same(maybe just diagonally) but the difference in drag between cork and feather is big too so no chance.

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    What were the competing systems ? (aside from Hawk Eye)

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    am i right to say that hawkeye's result is the statistical probability of the likely landing site based on the observed trajectory?

    hawkeye's result is not an observation but a calculation?

  15. #49
    Moderator Oldhand's Avatar
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    Quote Originally Posted by pcll99 View Post
    am i right to say that hawkeye's result is the statistical probability of the likely landing site based on the observed trajectory?

    hawkeye's result is not an observation but a calculation?
    You are spot on.

    It's a calculated landing point.
    It might or might not be precisely the same as the actual landing point.

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    Quote Originally Posted by Oldhand View Post
    You are spot on.

    It's a calculated landing point.
    It might or might not be precisely the same as the actual landing point.
    If I am right, then it's not worth $60,000 per tournament to have hawkeye.

    Slow motion replay (at above 1000 fps) is sufficient.

    Having more cameras from different angles and higher capture frame rate would be better investment.

  17. #51
    Moderator Oldhand's Avatar
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    Quote Originally Posted by pcll99 View Post
    If I am right, then it's not worth $60,000 per tournament to have hawkeye.

    Slow motion replay (at above 1000 fps) is sufficient.

    Having more cameras from different angles and higher capture frame rate would be better investment.
    Nope.
    It would be costlier if you want broadcast quality.

    However, I agree with you that our cash-strapped sport doesn't need such a costly system right now.

    Hawk-Eye is much more than an electronic line-judge or dispute adjudicator.
    The system has several add-ons that can add punch, flavour and colour to the broadcasts.
    For now, it isn't clear if the BWF intends to make use of those 'additional' features.

    Also, a camera that shoots 1000 (or more) frames per second could be very cheap or very costly.
    One of those Casio EX series cameras would probably cost a few hundred dollars.
    But a professional unit like the Phantom Flex would cost in the region of $100,000.
    (The costliest model - the full Flex4K - costs over $170,000.)
    The difference in price is actually the cost of the (vast) difference in quality.

    The Hawk-Eye system relies on not just the shuttle's position-over-time as seen by a 2D camera (in fact, it computes the shuttle as a stable flight-point over which the shuttle's in-flight profile is overlaid later for television replays) but on the shuttle's continuously changing position-over-time-and-space in a mapped 3D environment.

    To put it in another way, the system relies on the tracking devices placed around the court to pinpoint the shuttle's position at any given point in time and then constantly compares the changing values against an unchanging reference (the unchanging reference = the 40mm lines on the badminton court) to compute the path in 4D.

    In the simplest terms, Hawk-Eye tracks in 2D (x,y), maps in 3D (x,y,z), then predicts in 4D (x,y,z + time)

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