Talk:Hawk-Eye

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Old un-organized discussion

Hawk-eye is unreliable in the extreme. This must be emphasized. I disagree with the previous comment. Extensive testing on Hawk-Eye show that it is very accurate at plotting the true trajectory of a cricket ball. The only contentions issue is its predictive capabilitites after a ball has struck the batsman. "Neutrality" hardly seems an issue. It has been known to show the ball going in entirely the wrong direction, showing a googly as a leg break, even though the ball had clearly begun to spin as a googly before it hit the batsman. First of all, people on this page need to learn to sign their comments. On the substance, I do not understand what is disputed here. The author of the first comment did not provide any evidence or even references to back up the statement that Hawk-eye is unreliable. I wantch all major tennis events on the TV and not once have I heard any suggetsion that it was unreliable.BorisG 12:26, 3 April 2006 (UTC) I completely agree with Boris. It is acurate within 5 millimeters, according to Pat McEnroe. Shot-spot is different. It doesn't use the same technology. Shot-spot is acurate within 15mm, if you believe ESPN. Skislope15 22:15, 18 March 2007 (UTC)

Microchip

Is the information on the micro chip in tennis balls corrrect? I can't find info. on it on Hawk-Eye site. --84.92.136.183 14:53, 8 July 2006 (UTC)

I also find that claim rather odd - as it goes against the basic visual trajectory tracking principal on which hawkeye was founded. I think we definitly need some verifiable sources / citations for it, or else we should consider removing it. Triponi 10:33, 9 July 2006 (UTC)

I also find the claim that "The use of Hawk-Eye in tennis uses a unique microchip system that is fixed on a wire frame inside the tennis ball" extremely hard to believe. And I was also unable to verify it. So I've removed it from the article. - dcljr (talk) 06:10, 16 July 2006 (UTC)

There are no microchips implanted in tennis balls for use in connection with Hawk-Eye. Hawk-Eye's ball tracking for line calling and is based on high speed cameras placed around the court which are hardwired to powerful computers with customized visual processing softwareRnl58 15:48, 18 May 2007 (UTC)RNL58

I can verify, there are no microchips of any kind in any tennis balls used for competitive play, professionally, or on the collegiate level. Let us ignore, for the moment, the logistic problems with a microchip inside a rubber ball that gets smacked at 130+MPHs . Over the years, (the last 5 most prominently) there has been a massive division in the tennis world, specifically about the weight of the balls used at different tournaments. We're talking about tenths of an ounce here. Even now, amoungst the former best of the game, such as Johnny McEnroe and Cliff Drysdale, there is a looming uncertainty regarding the current ball weight in many of top tier tournaments (Grand Slams, Tennis Masters Series etc.) But, back to the direct implications... this isn't a solid rubber hockey puck that has a huge weight to mass ratio, and is frozen, and vulcanized... this is a hollow tennis ball, that is made out of flexible rubber, designed to bounce, and contort, and be hit at speed in excess of 150Mph. I hope your microchip is made entirely out of adimantium. <OKay Wolverine!

Cyclops

I remember seeing something in tennis a few years back very like Hawk-Eye. The commentators, however, referred to it as Cyclops. Is it just the same technology? 194.83.144.16 13:05, 9 January 2007 (UTC)

Cyclops is totally different - it uses infrared beams to call balls out on the service line, but doesn't give any other positional information. 143.252.80.100 21:12, 24 January 2007 (UTC)

Live Hawk-Eye?

In Tennis, is Hawk-Eye capable of calling in's or out's live? --The preceding unsigned comment was added by 60.241.129.19 (talk) 11:42, 10 January 2007 (UTC).

Other Sports

Does anybody have any evidence that Hawk-Eye is used in sports other than Cricket and Tennis, as is claimed in the first line of the entry? Tonksville 23:20, 28 March 2007 (UTC)

Nadal complaint

The Nadal complaint bit needs a bit of a work over. I originally thought he was just showing a hissy-fit as tennis players are want to do when things don't go their way but reading the reference it appears several people (including his competitor) agree it was out, contrary to Hawk-Eye. It would be good to look into this further to. For example what did MacCam suggest if it was used? Or if not, did instant replys suggest anything?Nil Einne 00:30, 25 April 2007 (UTC)

Nadal apparently paid his competitor to say that stuff. --Preceding unsigned comment added by 123.255.54.179 (talk) 02:53, 16 September 2007 (UTC)

This bit "The Hawk-Eye technology was used in the 2007 Dubai Tennis Championships with some minor controversies. Defending champion Rafael Nadal accused the system of incorrectly calling an out ball following his exit. The umpire had called a ball out; when Mikhail Youzhny challenged the decision, Hawk-Eye said otherwise.[4] Youzhny said afterwards that he himself thought the mark may have been wide but then offered that this kind of technology error could easily have been made by linesmen and umpires. Nadal could only shrug, saying that had this system been on clay, the mark would have clearly shown Hawk Eye to be wrong.[5]" is quite poorly worded.

"Nadal accused the system of incorrectly calling an out ball" - it was out and incorrectly called in, or it was in and incorrectly called out?

"The umpire had called a ball out; when Mikhail Youzhny challenged the decision, Hawk-Eye said otherwise." - Otherwise? Other than the umpire or other than Youzhnhy?

It may be clearish from the context but it could still be rewritten. Bejjer (talk) 17:56, 6 June 2008 (UTC)

it should probably be mentioned that hawkeye has 5% error margin on average in the diameter of the ball. That means any close calls with in a certain range of the line will have a certain error percentage. Thats about 3mm. This means if hte ball is within 3mm of the line, hawkeye is wrong 5% of the time. If its within 1mm its wrong about 12% of the time, if the edge of the ball is exactally on the line hawkeye is obviously 50% wrong. Hawkeye was chosen because it was more right than humans when the ball is within 5mm of a line, but it can still be (and often is) wrong. Hawkeye also predicts how much the ball squishes, it can't always see this, it does this prediction based on speed and incident angle, but can't see spin, which often causes the impact zone to be biased and not a egg shape, which gives more error. Again that error as found to be less than what a human would. --Preceding unsigned comment added by 58.111.143.218 (talk) 13:02, 1 February 2009 (UTC)

Cricinfo 3D

Does crickinfo 3D use hawk-eye to gain the data for what it displays? Nil Einne 01:14, 25 April 2007 (UTC)

Misleading Intro?

The introduction says Auto-ref was developed in 2000 while Hawk-eye was "put forward" (whatever that means) in 2001. This suggests that Auto-ref was the original technology. Is this the case? Given that the article later states that Hawk-eye was used at a sporting event three years earlier than Auto-ref, I'm assuming that the two dates given in the introduction relate to different points in the development of each technology. If this is the case it is very misleading and needs to be changed by someone who knows the full details. 212.140.167.99 14:37, 5 May 2007 (UTC)

As this article is about Hawk-Eye, not ball tracking systems in general, details of autoref should go elsewhere. Sjmtlewy 30:31, 25 May 2007 (BST)

does any one have try to make his own software like hawkeye?

can some provide me the information if any one have try to make his own software like hawkeye?

Ball Coating

Could a tennis ball be coated with something either inside or outside its rubber,in order to detect with more accuracy?Sigleyy (talk) 17:22, 17 January 2008 (UTC)

Operation

This article definitely needs some work. Can anyone provide more information on how Hawk-Eye actually works? Even basic information like 'it tracks the ball visually using a camera', if this is the case? Presumably, if this technology is patented, then details must be available in the patent applications.

Also, an outline of the tech's pros and cons could be good, with examples of when it has failed or excelled. This is shown to some degree in the Tennis category, but it really needs cleaning up. smiler (talk) 13:57, 1 May 2008 (UTC)

Calibration and uncertainty

As an engineer, I have to say that all measurement systems have uncertainty and need calibration. Nothing said by any of the users [that is TV] reflects any aspect of this. Think about this. Some displays on TV of so-called gaps [OUT] or overlaps [IN] can only be one millimetre or less. I have several questions.

Exactly how accurate is it in measuring the Ball position? It must be worse than a millimetre or two. Why does it not say that anything closer to the line than that accuracy is 'uncertain'?

Equally vital is how accurately it measures the line position. Does it assume a theoretical line position or is the actual line position [as used by the player!] input from actual measurement on each court?

Does the shape of the ball footprint actually calculated and displayed depend on the shot? It must vary with ball speed, spin and angle. Or does Hawkeye use the assumed ball sphere diameter and not the footprint at all?

Is it calibrated several times a day [just like the poor old low tech net!]? It needs to be.

Is Hawkeye mainly tricky display and not substance? Just how good is it really? Engineer jon (talk) 21:23, 1 July 2008 (UTC)

Well, judging by the article atm it's pretty useless or at least there are people who would like to convey that impression. Hakluyt bean (talk) 23:50, 1 November 2008 (UTC)

The interesting question is, are there any published independent tests of Hawkeye's accuracy? The only numbers we ever hear seem to come from people with a vested interest in the technology. I am actually a supporter of increased use of Hawkeye, but I find it very hard to argue the case without reliable data. Colin: 130.225.25.207 (talk) 11:16, 14 May 2009 (UTC)

Hawk-Eye vs ESPN's "Shot Spot"

"Shot Spot" redirects to this article; however there is no mention in the article of Shot Spot or its relationship to Hawk-Eye. So far I've found multiple instances of the following claims:

• Shot Spot is an ESPN rebadged version of Hawk-Eye

• Shot Spot is a downgraded version of Hawk-Eye that uses fewer cameras

• Shot Spot and Hawk-Eye are completely different implementations of the same technology, and the two systems frequently provide different results

It would be desirable to have a line or two which clearly explained the relationship between the two, especially as ESPN is using Shot Spot in their coverage of the 2009 French Open while Hawk-Eye isn't in use by the tournament officials. I searched for official sources of information about Shot Spot but was unable to find any. G Sisson (talk) 22:01, 1 June 2009 (UTC)

This entry has been here, ignored, for four years. So far as I can see, there is still no discussion of Shot Spot as compared to Hawk-Eye, either on the Web or here at WP. It's a natural question that would lead one to consult WP, but WP still has nothing to say. There are additional systems, as well, such as Auto-Ref, which is mentioned here briefly, and Cyclops. These systems for analyzing various ball-using sports have been around for almost 13 years, yet have very poor coverage in WP. Note: these technologies are not used officially at the French Open, in spite of the fact that Hawk-Eye is actually installed there and used by TV coverage, because clay retains the mark of the last-played ball, and officials there feel that this is sufficient for judging plays. David Spector (talk) 15:48, 9 June 2013 (UTC)

Accuracy Complaints

I am currently studying the HawkEye system after someone noted that the graphic footprint is typically almost the full diameter of the tennis ball, 2.52" (64mm) by caliper measurement.

It's quite impossible to compress a tennis ball to anywhere close to its spherical diameter. Try it. Even using mechanical means, the ball would explode anyway.

By nearly sitting on the ball, I was able to compress it to no more than 2" (50.8mm diametrically) of surface contact.

This means that the actual contact footprint of the ball is at the most extreme a minimum of 1/4" (6.3mm) inside the perimeter of an uncompressed tennis ball.

Everyone will have noticed that many of the graphics show an obviously-oversized compression footprint on both the static (roughly circular as in a drop shot) and the dynamic (highly elliptical as in a driving shot) final graphics.

The more you think about it the more you realize how absurd their typical graphic footprints are, and this applies to all types of shots.

Although the elliptical contact shape of a passing shot is accurate in principle due to roll, the minor diameter of their graphic ellipse is far too large to be an accurate representation of the actual contact footprint. This applies primarily to sideline calls.

However, this also calls into question the accuracy of the footprint for baseline calls as well. Although the ball will obviously roll on contact, where does that contact point actually start?

If one simply uses the full ball diameter to determine that in the graphic, then obviously those graphics will likewise be off by the 1/4" minimum difference in diameters since the ball could never be compressed that much even on the most powerful shot.

Thus, in all of the above cases, any graphic showing the ball to be touching the line, and hence called "IN" would in fact be out by a minimum of 1/4" (6.3mm).

Given his large number of failed challenges, I originally thought that Federer was simply a poor judge of actual ball contact, but having taken the measurements and generated the computer drawings, I now believe he was likely correct on many of his challenges and he is probably correct on his overall assessment of the system's accuracy, or lack thereof.

And that doesn't even take into account the inherent video and software inaccuracies mentioned in other comments, which add even more to the margin of error.

Again, any graphic showing point contact or contact less than appoximately 6mm inside the line should IMO be called "OUT". Such a ball could simply not have actually touched the line, so if it was called "OUT" that call should not be overruled by the current HawkEye graphics.

I like and approve of the HawkEye concept and would prefer that it become standard practice, particularly in the major tournaments, but from my determinations at very least they need to clean up their software interpretations and graphics because the current system is making a large number of bad calls, which is exactly what none of us wants. Jfcj1 (talk) 13:40, 4 June 2009 (UTC)

The above is original research: because Wikipedia is a encyclopedia, everything must be verifiable from reliable sources and not the original research of contributors. Therefore, the above information cannot be used in the article and is therefore off of the topic of improving the article. Jfcjl, in the future, please use talk pages only to improve the article and not to discuss the topic. - Enuja (talk) 15:34, 5 July 2009 (UTC)

Reply: ? "Discussion" IS a talk page, unless there's a different meaning to the word in your neck of the woods.

As for verification, simply make a few measurements yourself, if you know how to measure anything, that is.

And why should anyone wait until "reliable sources" decide to analyze this? It's plain as day.

Since the footprint has without any question been oversized, how "reliable" would existing sources be, regardless?

Note that the graphic footprint at this 2010 U.S. Open has indeed been reduced. That's good.

It's still a bit larger than real measurements allow, but given the 3mm margin of error, it's getting pretty close.

Since the goal is to improve the system, this is an appropriate forum for discussion. Jfcj1 (talk) 18:44, 10 September 2010 (UTC)

Dear Jfcj, Enuja is correct. Please familiarise yourself with WP:OR and WP:NOT#FORUM. The latter states: bear in mind that talk pages exist for the purpose of discussing how to improve articles. Talk pages are not mere general discussion pages about the subject of the article. Since original, unpublished research cannot be used to improve the article, please refrain from adding this material here. This does not mean you are wrong, it just means we cannot include this in the article. - BorisG (talk) 13:39, 11 November 2010 (UTC)

The problem with speculation by very intelligent people inexperienced with analyzing ball impacts professionally, and not fully knowledgeable about the physics of such events, is that they can come up with reasonable-sounding analyses that are nevertheless incorrect. A ball impacting at high speed, with spin, wind, and other dynamics, will not act at all like a ball under static pressure applied to its topmost surface. From what I have read, there are an incredible number of considerations the effects of which must be combined. One nonobvious effect is that a struck ball will vibrate, changing its cross-section according to some vibratory mode, as it travels through the air. It will not impact in its static spherical shape, even at its first point of impact. The ball then slides along the ground, affected by the elasticity and other characteristics of the earth. It generates ground waves and a wind of its own (low frequency sound waves) that can spread the visible effects of its impact. The intersection of ball and ground is complicated by these and other factors. What we need in an encyclopedia when analyzing ball impacts is the contribution of a true expert, someone who has worked with this model and its data professionally. Even a professional physicist in another field, or a college professor, is not expert enough. While amateur collection of secondary reliable sources works fine for many topics, it fails when sources are missing, as they are in this relatively new field of proprietary technology. Only correct information, not intelligent guesses, should appear in encyclopedias. In this complex real-world case, correct information for these complex technologies cannot be determined by outsiders using reasoning based on basic physics and commonsense. David Spector (talk) 19:22, 8 June 2013 (UTC)

Update needed

Needed because of the review system in cricket. To start with hawkeye only showed upto impact moment. But now the ICC allows umpires to see the ball all the way to the stumps as per the world cup at the moment. An update definatly needed. KnowIG (talk) 12:58, 10 March 2011 (UTC)

Cricket

Cricket part of the article bit vague. I did not understand from article whether hawk-eye used by referee or not. I mean, can hawk-eye technology change match result? - (saidaziz) 178.88.248.109 (talk) 07:29, 5 January 2013 (UTC)

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Contradiction in the camera count

The summary section states, "The system works via six (sometimes seven) high-performance cameras", but the Method of operation section states, "For tennis there are ten cameras." The Tennis section twice references ten cameras.

Should we update the summary section to read, "The system works via six to ten high-performance cameras"? Maniaphobic (talk) 17:44, 3 July 2019 (UTC)

1mm formatting issue?

There's an issue with formatting under the "Doubts" section: "In the 2007 Wimbledon Championships [[2007 Wimbledon Championships – Men's singles rap|1 mm}}"

I'm not sure what this sentence is trying to say, so someone should fix this.