Naked Science Forum
General Science => General Science => Topic started by: turnipsock on 01/02/2009 22:56:53
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(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fwww.hawkeyeinnovations.co.uk%2Fimages%2Fthumbs%2F1183028537_hires-line1.jpg&hash=19c0ae7eb7b3301fa48dbdebd05fffb7)
How does Hawkeye allow for the force that a ball hits the ground with? If a ball is smashed into the ground it will deform more than a ball dropped just over the net. The imprint it would leave on the ground would be different. I'm sure there are other factors like ball/air temp, air pressure, etc. There must be a point where tennis players realise that when their drop shot was called out, they think Hawkeye might show it as 'in'.
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fwww.imveurope.com%2Ffeatures%2Fimages%2FIMVEJun07SportFigure%25201.jpg&hash=3449ad6fd40407e182524e7b4ed622ef)
What does the panel think?
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Well, hawk eye isn't that accurate when it comes to cricket so that's why during the trial referral system the third umpires were not allowed to use it.
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I would have thought it was more accurate with cricket as there isn't an issue with the ball deforming and affectingthe result.
A good test for Hawkeye would be to put it up against Cyclops.
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It will show the projected trajectory of the ball through the air, after is has hit the pads, i.e, for a lbw decision, however, whether the ball will actually do this or not is currently the issue.
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Whenever I've seen Hawkeye replays it does indeed seem to show the contact area of a distorted ball, not an undistorted one.
This is not to say that it is always right, but it does seem to take the distortion of the ball in to consideration.
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I think Hawkeye is great for tennis. But for cricket it is a bit dodgy as they have to predict the path of the ball. How about using hot spot for tennis?
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Whenever I've seen Hawkeye replays it does indeed seem to show the contact area of a distorted ball, not an undistorted one.
This is not to say that it is always right, but it does seem to take the distortion of the ball in to consideration.
The point I was trying to make was that the distortion varies with the force that the ball hits the ground therefore the contact patch is not constant.
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As long as the 'error' is consistent - and it is likely to be, because the balls are made to such tight tolerances - the players will play to the system, learning how to get the maximum out of it. If, indeed, they are able to play that accurately then it will not disadvantage them as long as Hawkeye is consistent from court to court. If they aren't good enough then it will make no difference compared with their own random input.
It is an interesting bit of Physics / Engineering, though.
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Whenever I've seen Hawkeye replays it does indeed seem to show the contact area of a distorted ball, not an undistorted one.
This is not to say that it is always right, but it does seem to take the distortion of the ball in to consideration.
The point I was trying to make was that the distortion varies with the force that the ball hits the ground therefore the contact patch is not constant.
Yes, and that was exactly why I commented, to point out that this does seem to be taken in to consideration.
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Why does it need to be taken into consideration? If it is consistent then it does what is required. It is bound to be better than some dozy old sod in a white hat, sitting on a chair. My point is that the machine imposes an 'envelope' of permitted shots which the players will adapt to. It is fair because it is consistent. The fact that the virtual line is not exactly where the painted line is doesn't matter. Needless to say, this only applies when the systematic error is small enough not to be obvious.
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Consider a drop shot, maybe hitting the net cord maybe not, and then just dropping out to the linespersons eye. The player knows that hawkeye will deform the ball a lot more and it will probably show the ball as 'in'. The linesperson will have their wages reduced or sacked or whatever. The whole thing just makes people play more drop shots. How come you never see the ball boys (generic term) on Hawkeye?
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Hmm... isn't that a little bit cart-before-horse Sophie? Should the sports really be changed to fit in with the level of adjudication, rather than trying to increase the quality of adjudication so that it's adequate to the sport?
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I'm not sure the ball will be deformed more, most of the ones that we get to see are all from serves or base line rallies so they are of course deformed. But drop shots... I've seen ones where the ball is hardly deformed at all.
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Consider a drop shot, maybe hitting the net cord maybe not, and then just dropping out to the linespersons eye. The player knows that hawkeye will deform the ball a lot more and it will probably show the ball as 'in'. The linesperson will have their wages reduced or sacked or whatever. The whole thing just makes people play more drop shots. How come you never see the ball boys (generic term) on Hawkeye?
You seem to be arguing from the premise that it's impossible to model the effects of variable forces on a deformable object where just about all of the characteristics are not only well known, for the court surfaces, but specified, for the balls.
Why would you want to see ballboys on Hawkeye? What purpose would that satisfy?
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I'm not sure the ball will be deformed more, most of the ones that we get to see are all from serves or base line rallies so they are of course deformed. But drop shots... I've seen ones where the ball is hardly deformed at all.
The amount of deformation isn't magic and unknowable; it's very well understood and relatively easy to model with current technology.
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Exactly, hawkeye is pretty foolproof. For tennis at least...
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If a player smashes a ball into the ground the ball is bound to deform more than one of these floating Henman slices.
It would be good to put hawkeye on the ballboys (especially when they get hit) as the Wimbledon ballboys were obviously very slow last year. It may be something to do with the culture in that area, but I, for one, was dissapointed at their ineptidude.
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What do you mean: put hawkeye on the ballboys???
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Hmm... isn't that a little bit cart-before-horse Sophie? Should the sports really be changed to fit in with the level of adjudication, rather than trying to increase the quality of adjudication so that it's adequate to the sport?
Surely every good player finds the envelope of the adjudication. It's not possible to monitor eveyr factor to 100% accuracy. I have a feeling that Hawkeye may not be as good as people think. Does that matter for entertainment? If the public are happy then it's doing it's job. There's so much rubbiish talked about sport in general and it's not a matter of life and death.