ICC news

Independent tests for ball-tracking systems

ESPNcricinfo staff

February 15, 2012

Comments: 42 | Text size: A | A

Hot Track: a combination of Hot Spot and Virtual Eye tracker, June 16, 2011
The accuracy of Hawk-Eye and Virtual Eye is being put to the test © Virtual Eye
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The most contentious aspect of the Decision Review System - the ball-tracker - is being put to the test by the ICC at the Cambridge University to establish the accuracy of the two rival tracker systems accredited by the ICC for the DRS.

The ball-tracking technologies currently in use for the DRS - the Hawk-Eye and the Virtual Eye - are being tested by a company called Computer Vision Consulting Limited. The results of the test should be available to the ICC's cricket committee in time for its next meeting in May this year.

Dave Richardson, the ICC's general manager of cricket, told ESPNcricinfo in an interview that the company had been asked to review "the level of accuracy and reliability of the two ball-tracking companies ... In terms of accuracy we want to know whether their virtual depictions of where the ball has pitched and where the ball has impacted the batsman accord with the reality, and whether their predictions as to where the ball would have hit the stumps are correct."

The issue of reliability he said was to find out "the percentage of times they can deliver an accurate tracking. If, in a Test, there are 60 lbw appeals and the ball-tracking technology is only able to deliver an accurate tracking on, for example, 50 of those occasions, then they would not be regarded as very reliable. On the other hand, if they were getting it right on 97 out of 100 occasions, we would probably regard that as being acceptable."

Before the introduction of the DRS in 2008, Richardson said, the ICC had conducted some basic manual testing which had left them satisfied before launching the system. The current test he said was "a far more detailed review by a completely independent party. Hawk-Eye and Virtual Eye both tell us how accurate they are, but this will verify those claims." The contention between the two rival ball-tracker technologies was largely around the number of frame rates offered by their cameras in order to provide data to work with the ball tracker.

The ball-tracking technology was first included as part of the DRS' earliest mandatory requirements but in June, the ICC made it optional, and the Hot Spot infrared thermal imaging camera compulsory. Both technologies have come under criticism, due to a series of what appeared to be flaws.

When responding to the criticism that the ICC should have tested all the available DRS technology thoroughly, Richardson said, "We were satisfied with the testing we did. We tested the accuracy as far as we could, and to an extent it showed that the technology was at least accurate and reliable enough for it to be used in the manner that we have used it."

Most misgivings about the accuracy of the technology, he said, came from people being "misled" by what they saw on TV or the angle of sight while watching a contentious dismissal. The picture of slow motion replays under DRS often came, he said, from cameras set to the side of the bowler's arm rather than directly behind it.

"People see a replay on TV and say, 'That looks as if it was hitting leg stump.' But then Hawk-Eye shows it just missing and you say to yourself, 'That just cannot be.' But what people don't realise is that the camera for the slow-motion replay might not have been behind the bowler's arm. There are three cameras in a row and the one used for slow-motion replays is one of the ones on the side. So, often the picture you see on your TV screen is slightly misleading."

What was needed, he said, was to give the viewer "the evidence to prove that [people] should trust the evidence provided by the ball-tracking technology, not what they might see on television."

There were no plans to test the Hot Spot technology because, "Hot Spot is real, it's not a virtual picture." What the owners will be working on is to make their cameras more sensitive so that the "smallest of touches" could be visible. The priority of the infra-red cameras in use in the DRS was their "sensitivity, that is, its ability to generate a visible heat mark as opposed to clearly defined pictures which look nice but do not provide the level of sensitivity to pick up the faintest of edges."

He admitted what while Hot Spot cameras may not be able to pick up the very faint touches, "they will never show a mark where there is no touch and they are also very useful in distinguishing between whether the ball has touched the bat or gloves, as opposed to, for example, the thigh guard, arm guard, shoulder or helmet."

He said in time, the ICC would like communication between the on-field and third umpire during a DRS discussion to be heard on TV. "Hopefully when the umpires are so confident in the system and so well versed in using it, we will be able to do that. That's the aim."

© ESPN Sports Media Ltd.

Posted by Ameega on (February 16, 2012, 11:34 GMT)

Spot on Punters_Mate! Well said!

Posted by zenboomerang on (February 16, 2012, 9:00 GMT)

@jmcilhinney... Ahh, ignorance is bliss & cherrypicking a comment is even worse... Please show that the basic parameters of the original setting up of Hawkeye & its data analysis is now being curtailed by a new approach... Didn't Hawkeye use shadows as part of their original research?... lol... Sorry I don't accept your put down... Please use factual data techniques rather than random slurs - though I am used to that from pommies... I've moved on - have you?...

Posted by razi_hasan on (February 16, 2012, 8:41 GMT)

I don't understand why 'royramesh' brought Saeeed Ajmal's action in this DRS debate. U have no sense ...

Posted by Fast_Track_Bully on (February 16, 2012, 7:18 GMT)

Thanks to BCCI for the ICC decision to test the DRS system...those who criticize India for everything do not understand that the resistance from BCCI would make a perfect DRS without any errors.

Posted by stark-truth on (February 16, 2012, 7:10 GMT)

The beauty of DRS is that it takes out of the equation blatant incorrect decisions of the umpires, especially in lbws.

Posted by Moseley76 on (February 16, 2012, 5:47 GMT)

I've noticed some ridiculously ill-informed comments regarding the technology employed by both Hawk-Eye and Virtual Eye by a number of the participants here. Perhaps a read of http://en.wikipedia.org/wiki/Motion_Capture would assist. I've used similar technology in a number of fluid dynamics and fluid-structure interaction experiments with very pleasing results. Presumably the ICC and the commercial television networks involved can and would source much better equipment than what I've used so I can only imagine the accuracy of their optical tracking system for DRS. The only errors that I can envisage in the ICC's ball tracking system are spatial/lens errors introduced by distance from the cameras to the ball. The system can of course be calibrated to quantify these errors. Good luck to the Cambridge researchers involved in the testing!

Posted by ONE4U on (February 16, 2012, 5:29 GMT)

The game is more in the hands of a camera operator than umpires. As in the case of infamous world cup incident of Tendulkar's lbw call; the slightest of movement of camera directions through the operator's lever can prove a clear out to be not-out.

Posted by jmcilhinney on (February 16, 2012, 5:20 GMT)

I cannot recommend strongly enough to everyone who reads this article to click the "interview" link in the third paragraph and read that too. It has some very interesting information, including the fact that the researchers doing these tests already have systems that, given the geographical location and date, can use shadows to help determine the exact position of an object. This debunks statements like "the methology used to build Hawkeye is the same that will be used to test its accuracy" by @zenboomerang. There is a lot of ignorance around about DRS and the technology it uses. That is at least partially the fault of the ICC. They should do all they can to ensure that the viewing public know as much as possible about it.

Posted by jmcilhinney on (February 16, 2012, 5:16 GMT)

@Saad Sabri, that's the most ridiculous argument I've heard. Of course DRS can not magically know that the ball would have spun or swung if it had not hit the pad but then neither can an umpire. Umpires have to use their best judgement based on what they see of the ball and what they know of similar balls they've seen in the past. DRS does exactly the same thing. As for a ball hitting the batsman on the full, a rule was introduced many years ago that the umpire must assume that such a ball was going to continue straight on regardless of any other factors, so that argument holds no water either. Proponents of DRS all agree that it is not perfect and never will be, but that's very different to your completely ridiculous clain that it is not accurate and never will be. Umpires will never be perfect but you seem to think that that are accurate enough.

Posted by jmcilhinney on (February 16, 2012, 5:11 GMT)

@SanjivAwesome, the ICC did not rush out untested technology as you say. They performed their own tests and were happy with the results. It is the BCCI's refusal to accept the ICC's decision on DRS and the resulting fire-storm that created the perception of unreliability. The BCCI said "no" and the rest of the world said "bad BCCI" and then many Indian supporters proceeded to point to anything they could to justify the BCCI's stance whether it actually made sense or not. It certainly has become "us against them" with little actual logic or reasoning on either side some times. Having said all that, if the ICC were happy with DRS and mandated then the BCCI should have accepted it. If they had issues, they should have gone away themselves and had independent testing done to show that it didn't work, not the other way around.

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