Replay Technology Will NOT make 100% Correct Calls

More blown calls in a major sporting event. This time in the 2nd game of the Major League Baseball World Series, between the New York Yankees and the Philadelphia Phillies. Chase Utley of the Phillies was called out at first base, when video evidence suggested he had touched the base before the ball hit Mark Teixeira’s glove. In the same game Ryan Howard was judged to have caught out Johnny Damon, when the ball looked to bounce before hitting his glove. There have been a number of poor calls in this seasons MLB playoffs once again, and blown calls are happening in numerous other sports, including soccer and tennis.

The technology of high definition and high speed video of today can easily eliminate many of these blown calls. Sure there is the argument that using video replay can slow down the game. In baseball in particular this would be truly frustrating, but we would I think all prefer to see the right call made most of the time, particularly in big games such as the World Series.

Cricket is a great example of where camera technology is used to good effect. The cameras are setup side on to the crease (batters line) and can see both the wickets and the crease. In most cases just this one camera would be enough to determine the position of the batter as well as whether the wickets bails had been dislodged. If the umpire on the field is unsure of a run out situation, he will refer the decision to the camera technology, or the 3rd umpire, who will make a definitive decision after reviewing the video footage.

Although we definitely support the use of video analysis to assist umpires and referees, it is important that everyone; umpires, athletes and fans understand that even with video analysis a call can not be 100% correct every time.
Video footage cannot always capture the event from the correct angle or the video cannot be slowed down sufficiently to determine some calls. The fact is that the video footage may not show enough evidence to support or over rule a call.

Fans in particular make the mistake of believing that video evidence will always be able to determine whether a call is correct. Unfortunately this is not the case.
If the camera reviewing a line call or judgement does not have a direct view, then the video image may not help to determine the accuracy of the umpire's call. When close calls are viewed from an angle given by a television camera, they can sometimes give misleading evidence of the accuracy of the call. This can be particularly problematic for example, when using one camera angle to determine whether a base runner has been thrown out. The base runner is running between the bases and the camera could be setup at a good angle to view when the runner touches the base. However, and here is the problem, the ball may be thrown in to the fielder from anywhere on the field (this cannot be determined in advance), therefore the camera setup to view the runner may not be in the best position to accurately determine when the fielder caught the ball and it will be possible for incorrect judgements to be made. If on the other hand we have a great view of the fielders glove and ball, we may have the incorrect perspective of the base runner and when he touches the base.

Of course these 2 situations did not take place in the 2nd game of the MLB World Series, but they also cannot be discounted.

Take a look at the 2 photographs below.


In the above pic we have the view from one camera and shoe looks like it is on the edge of the mat.
Now lets take a look from a second camera with a better view of the edge of the mat and the shoe.

Of course it is pretty obvious from this camera angle that the shoe is just short of touching the mat.
From this we can see that the incorrect camera angle could result in an incorrect call.

The problem of incorrect camera angle could be solved by having multiple cameras, all synchronized with a time source and calibrated so that the 3D position of the ball can be determined. This is how the Hawk-Eye system for Cricket and the Tennis challenge system works. Beside the fact that this type of technology requires numerous cameras, can be very expensive and requires processing time before a decision can be made, it too can suffer from inaccuracies when the ball or target being tracked is hidden from the view of a number of cameras. This can often be the case when their are numerous players on the field, or the lighting is not ideal.

So we know that video analysis of umpiring and refereeing decisions are not 100% accurate. In fact the Hawk-Eye system claims they have an accuracy of 3.6mm. This means that the ball can miss the line by 3.6mm in Tennis and still be called in by the system. In NFL football when a call is challenged and a review takes place, often the result suggests that there is insufficient evidence and the call on the field cannot be over ruled. This insufficient evidence occurs because the camera cannot get the best view of the ball and its position because of the scrum of players or a camera angle that is not optimal.

The umpire or referee has a distinct disadvantage to technology. He or she only gets one chance to get it right. If they fail to get into the best position, have the best view of the play, find the best perspective to catch all the action and happen to blink at the critical point, they could easily make the wrong call.
The camera even with the possible errors in perspective or lighting and the small errors with 3D tracking , can capture high resolution and high speed footage and replay it over and over again.
This advantage will ensure that technology will get the call right more often than even the best and luckiest umpires and referees and should be used whenever an umpire is unsure of the call to be made.

A final thought. While we wait for technology to be used, we should remember that even video footage could result in incorrect decisions. There will always be some statistical error, only a lessor error than those made by human umpires. Fortunately with technology, line calls can not be biased by emotion but only based on whatever video footage is available. With this technology even the teams we support will catch a few breaks in the long run.

Big Hitting Cricket in Twenty20

Visiting South Africa this month I had the opportunity to watch live cricket once again. I always enjoyed cricket, but it is difficult to watch international matches while living in the USA.

I had the opportunity to watch some ICC Championship 50 over cricket and then some of the Champions League Twenty20 cricket being played in India.
Twenty20 cricket is a highly explosive form of the game which is bringing great excitement to the cricket world. The Twenty20 game allows each team only 20 overs of 6 deliveries each to make a total. This means that the batters need to make runs quickly and hit big shots off every ball. They cannot afford to miss or get no run from a shot. You can find more details on the laws of Twenty20 cricket here.

As I watched the Champions League Twenty20 cricket and some big innings from the likes of JP Duminy and Jacques Kallis, I thought it would be fun to look back at a 2007 World Championship game between India and England in which Yuvraj Singh of India, hits a six (the most runs you can get for one shot) off each ball of the over. A six is hit when the ball is hit through the air and carries over the boundry rope on the perimeter of the field. To hit a six the batter needs to hit the ball hard and high. Six spectacular sixes in one over for 36 runs. Check out the video below.

The Straight Drive in Cricket

Batting in cricket is altogether different from batting in baseball in both objective and technique as well as the bat itself. In cricket the batter can hit or play at and miss as many of the balls bowled as he or she wants with a flat faced bat and scores by running between wickets or hitting the ball over the boundary. In baseball, it is 3 strikes and you are out and home runs or base hits, hit with a rounded bat, are the goal.

In both sport, professional bowlers or pitchers can deliver the ball at around 100 miles per hour and therefore timing and reaction are very important. In cricket though the batter can play a shot anywhere on the oval field, even behind him as long as he does not get caught or run out (I will not go into the rules of cricket but you can find them here). This means that in cricket there are a large variety of shots that can be played that require exceptional timing as well as perfect technique.

One of the classic and most eye catching shots in cricket is the straight drive. Most of the best cricket batters in the world such as Jacques Kallis and Ricky Ponting play this shot with ease and little effort.

Here is some video of Sachin Tendulkar, another cricket batting legend playing some straight drives off one of the fastest bowlers around, Brett Lee. The first shot is slightly mistimed and the ball angles off his bat, but the next 2 shots are perfect examples of a straight drive.



His timing and technique in the second shot is perfect and therefore requires little effort to transfer power and speed to the ball so that it races along the ground to the boundary and 4 more runs.

Let's analyze the video and break down his technique:

• Tendulkar starts his movement by stepping with his front foot toward where the ball will bounce on the pitch and lifting his bat. As the ball is coming toward him at around 145 km/hr, he has very little time to react and therefore must move toward the ball and plan the shot he will play at the same time.
• As bowling in cricket requires the ball to bounce, it can change direction and speed quite a bit after the bounce. Stepping forward to the area in which the ball will bounce allows the batter to get closer to the bounce and reduce the amount of movement that can occur after the bounce. This also allows the batter to get over the ball and prevent the shot from flying through the air and giving one of the fielders a chance to catch it.
• Tendulkar brings his bat down straight with the flat face of the bat directed at the ball. Angling the bat will force the ball off in the direction toward which the bat is angled and also increases the chances of catching the edge of the bat or missing the ball completely. Although batters do sometimes play shots by changing the angle of the bat, you will not play a good straight drive with an angled bat.
• Tendulkar connects with the ball around 1:21. By pausing the video you will see that his bat is alongside his front leg at the point of contact. His weight is also forward and over the front leg. He does this so that he can hit the ball directly toward the ground giving no chance for a catch. This timing also ensures that he has perfect balance and control over the shot.
• He keeps his head down looking at the ball being hit off his bat and continues to keep his head down as he begins his follow through. Just as in other sports (golf, rugby place kicking) this helps him to maintain his balance through the shot and once again to keep the ball from lifting into the air.
• Tendulkar then continues to follow through keeping the flat part of the bat facing in the direction he hit the ball and bringing his arms all the way above his head. This ensures that he hits straight and all the way through the ball.

The results of this perfect timing and technique are obvious as the ball flies off to the boundary and 4 more runs for Tendulkar.

The 2009 ICC Champions Trophy begins September 22 and the likes of Jacques Kallis and Ricky Ponting and Sachin Tendulkar will be showing off their batting prowess and often flawless technique from which we can learn.

Cricket Bowling: Video Analysis of a Throwing Action

On the Video Analysis of Sports we are excited to show how video can be used to improve your performance in almost any sport. We are also interested when video or motion capture is used to study the intricacies of laws in sports.

This week Dudley came across an article about the use of a motion capture system to study the bowling action of a cricketer, http://www.gulfnews.com/sport/Cricket/10308342.html . For many years there has been controversy over legal bowling actions and numerous players have been called for suspect bowling. In fact the leading wicket taker in world cricket, Muttiah Muralitharan, was regularly called for a suspect action, early in his career. With the performance of 3D motion capture studies at the University of Western Australia, his action was finally ratified and was no longer called into question.

For those of you who know very little about cricket, here is a link with a brief explanation http://uk.cricinfo.com/link_to_database/ABOUT_CRICKET/EXPLANATION/ .
Bowling is the action of pitching the ball at the wicket (see link above) in an attempt to beat the batter.

There is a law in international cricket that the angle of the bowling arm (arm with the ball) cannot straighten more than 15 degrees during the final part of the bowling motion before releasing the ball. If it does then this motion can be considered illegal and in the end can result in a player being suspended from International cricket until he corrects his action.

It therefore makes perfect sense that video analysis is used to evaluate a cricket bowler's action before they are suspended. In fact the maximum change in angle was increased to 15 degrees based on a study using 3D motion capture analysis. Motion capture and biomechanical tests proved that it is almost impossible to bowl the ball without some flex or bending at the elbow and in 2004, it was discovered that many bowlers in International cricket flex their elbow more than the previously set limit during their bowling motion.

With video analysis we can:

1. Capture the motion with high speed cameras, so we can assess the motion frame-by-frame and concentrate on the part of the bowling action that is relevant.
2. Set up our cameras appropriately so we get a good view of the arm and how and where it bends.
3. Measure the change in angle of the arm using mathematical concepts rather than "eyeballing" it.
4. Capture the bowling action using multiple cameras to obtain a 3D view of the action and find the physical change in elbow angle rather than a 2D simple angle assessment.
   

The International Cricket Council (ICC) actually appoints a panel of human movement specialists to assess any possibly illegal bowling actions. This panel is instructed to use video and motion capture to analyze a suspect player's bowling and present their findings to a review board.

Here is a video of Muttiah Muralitharan bowling and taking the last few wickets on his way to the world record. His once suspect bowling delivery called the "doosra" is the first delivery you will see. In full speed and with the naked eye, it certainly looks like he is throwing the ball (straightening his arm by more than 10 degrees), but further investigation using 3D motion capture proved that this was not the case.

It is commendable that the ICC uses motion capture and technology to evaluate a rule that could cost a player his career. There are not many sports in which the player's action can be called into question; but all sports can benefit from some form of video analysis to improve players' performances.

If you have some sports video or are interested in analysis of a particular sport, let us know with a comment or send us an email.