CS675 Project Cricket Visualization Tool Muralidharan Dhanakoti 1. Abstract Mitigated by rapid advances in ball tracking systems, cricket visualization systems have emerged as an indispensable tool for every cricket team s think tank. Coaches use these systems to analyze the performance of his players as well as the opponent team s players, television coverage of the matches are enhanced using these tools by providing the viewer with critical insights on the game. This project is aimed at developing one such visualization system. Various visualization techniques are used to generate the following visualizations, Pitch map, Wagon wheel chart, Manhattan chart. 2. Background and Motivation Cricket teams of yesteryears often pined for some sort of visualization system which will assist them in analyzing the games played against a particular opposition so that they can better understand the other team s strengths and weaknesses so that they know what to expect when they play the same team again. With the advent of sophisticated ball tracking systems, their prayers seem to have been answered. These tracking systems installed on the cricket grounds monitor the ball s position right from the bowler s hand all the way till the ball is deemed dead. They various factors that these systems measure include the pace at which the bowler bowls, ball s bounce after it hits on the pitch, its swing in the air before and after the crossing the batsman, spin deviation of the ball after it pitches, the direction in which the batsman hits the ball, the height of the ball at the point impact of the bat and the ball, and the exact distance at which the ball hits the pitch. These measurements provide all the data one would ever need to comprehend the action. With the use of judicious visualization techniques one can create visualizations that will
help the team as well as the individual player to analyze theirs and opposition s game better, it helps the coaches in strategy planning and also it provides enhanced viewing experience to the viewers watching the proceedings live in a television. 3. Methods The proposed tool will have the following visualizations Pitch Map Wagon wheel chart Manhattan chart 3.1 Pitch Map Pitch map is a scalar visualization technique aimed at analyzing the performance of the bowler in a match or in a spell. This pitch map shows where the bowler pitched all the balls in his quota of overs in a match or in a spell. Since this chart is aimed at analyzing the performance of the bowler, balls on the pitch are colored according to a color table that reflects the goodness of each ball. The pitch was constructed as a plane and an image of the cricket pitch was mapped as a texture to this plane. The balls are represented as spheres with phi and theta resolution of 10. The stumps are rendered as cylinders with resolution of 25 and an image of a cricket stump is mapped as a texture. To generate this visualization the cricket pitch is divided into 6 length zones and 6 line zones, the different length zones determine the goodness of the ball delivered by the bowler. Two line zones are designated outside the off-stump and the leg-stump and the remaining two line zones are on the stumps.
Figure1: Pitch and the stumps Figure 2: Length zones
The 6 length zones and the balls corresponding to those zones are named as follows Short Short of good length Good length Over-pitched Yorker Full toss 3.1.1 Short This length zone starts midway of the pitch and the balls pitched in this zone are called short balls. Balls bowled in this zone by the bowler are deemed bad, the reason being when the ball is pitched midway on the pitch it gives the batsman more time to watch the ball and plan his stroke accordingly. This ball is lethal when aimed at the head or the ribcage of the batsman, but if the bowler gets the line wrong then the batsman can easily sway out of ball or even worse if the ball is bowled wide the batsman can quite easily clip the ball for four or even for six runs. Despite of having the potential to harm the batsman or at least frighten the batsman this ball is bad and therefore it is colored red indicating a bad or a danger ball from the bowler s perspective. 3.1.2 Short of Good length This length zone is a mixed bag for the bowler for the balls in this region can be hammered by the batsman if the line is wayward. When a bowler pitches consistently in this zone and also he maintains a good length the chances of him getting a wicket is high 3.1.3 Good length This is the best ball that can be bowled by a bowler, when the ball is in pitched in this region the batsman is not sure whether to play with the front foot or to stay on the back foot and when the bowler pitches the ball just outside the off-stump line in this length consistently no matter how good a batsman is, the bowler is going to have him in trouble and its only appropriate that these balls are colored green.
3.1.4 Over-pitched This length is what every batsman loves a bowler to bowl, whenever the bowler pitches the ball in this zone the batsman plants his front-foot forward and drives the ball invariably for 4 runs, so this zone is the most damaging zone for a bowler to bowl at. Balls in this zone are shaded red. 3.1.5 Yorker The bowler attempts to bowl this ball in the slog overs of the match when the batsman is ready to take chances in search of quick runs, when the bowler gets it right the chances that the batsman might miss the ball or might get strapped on the pads is very high, but the downside of this length is that it is difficult for a bowler to consistently bowl in this zone, balls pitched in this zone are also shaded green. 3.1.6 Full toss This zone is again a mixed bag for the bowler, if the full toss ball is low at about thigh high and aimed at the body, the batsman finds it tough to work this around on the other hand if it is bowled even a bit wide then it is rest assured the ball will reach the fence in no time. Balls in this zone are shaded yellow. Figure 3 Pitch Map
3.2 Wagon wheel A wagon wheel chart is used to analyze a batsman s performance. This chart shows where a batsman scored his runs and how he scored them, this chart can be used to analyze a batsman s scoring areas, using this visualization the bowlers can know where not to pitch to this batsman. 3.2.1 What is a Wagon Wheel? The cricket field is usually oval in shape and this oval region is divided into 8 zones namely Mid-wicket, Mid-on, Mid-off, Covers, Point, Third man, Fine leg, and Square leg. Wagon wheel visualization shows how many runs the batsman scored in each of these zones, apart from this wagon wheel chart also shows how these runs were scored whether these were lofted strokes or ground strokes, by quantifying the runs with the distance the ball traveled from the stumps and the height information for lofted strokes a vector field around the play field is generated and the rendered image resembles like a wagon wheel that s why this chart is called a wagon wheel chart. 3.2.2 Run Types In a cricket game the number of runs that can be scored in a ball is 6, if the ball is hit out of the playing field then 6 runs are awarded to the batsman, if the ball reaches the boundary of the field after bouncing on the field before reaching the boundary then 4 runs are awarded to the batsman, if the batsman hits the ball inside the field he runs across the pitch until the ball is collected and thrown by a fielder to either the bowler or the man behind the stumps called the wicket-keeper, if the batsman runs across the pitch once then the batsman collects 1 run, he can run the length of the pitch as many times he wants till the ball is returned to either of the above mentioned players, and the number of times the batsman runs across the pitch is collected by the batsman for that ball, usually the batsman runs either once, twice or thrice and collects as many runs.
Figure 4 Wagon wheel chart 3.2.3 Generating Vectors for ground strokes The zonal location and type of each run is read from the input file, a vector is generated from the middle stump to the specified location and color coded. Figure 5 Wagon wheel graph with Bezier curves for lofted strokes
3.2.4 Lofted shots Usually a four or a six hit by the batsman is lofted in air, and this stroke must be distinguished from the ground strokes for the wagon wheel visualization to be complete A rational quadratic degree Bezier curve is generated to record the lofted shots, the first control point being the starting point of every other stroke and the third control point is the positional data read from the file and the second control point is the midpoint of the other two control points except its y-coordinate lofted by the height the ball went up in the air, now by applying weights = 1 for each of these control points we generate a rational Bezier curve which is a parabola which represents the ball s trajectory. 3.2.5 Color Coding The color coding for these vectors is done from the perspective of the batsman, the sixes are the maximum runs he can score they are coded red, the fours are the next best he can do, they are shaded orange, the threes pink, the twos are purple and the ones are pale yellow. 3.3 Manhattan chart This chart kind of gives the summary for a game; this chart is inclined towards showcasing the bowling team s performance. Information regarding each of the 50 overs is recorded in this chart. Figure 6 Manhattan Chart
For each of the over bowled, the number of runs scored, the name of the bowler who bowled this over and the number of batsman dismissed during this over is recorded. 3.3.1 Generating the bowler - over grid The grid that is seen in the snapshot in the previous page is called the bowler over grid, it is called so because the two axes that define the grid s plane have bowler and over information encoded in them. The bowler axis has the names of the bowler s defining each cell, and the over axis contains the over number defining the cells. 3.3.2 Generating the runs scored The number of runs scored in each of the cells (over number and the bowler name) of the bowler-over grid is represented as a cylinder whose height is the number of runs and its center is the center of the cell (with an offset), a text actor that has the numerical value of the number of runs is rendered on top of each of the cylinders. 3.3.3 Generating wickets If a wicket fell in that over, a sphere is rendered on top of the cylinder (runs) to indicate a wicket fell, if more than one wicket fell in that over then a provision is made to render as many spheres as the number of wickets in that over. 3.3.4 Color Coding The color coding for this Manhattan chart is influenced by the number of runs scored in that particular over, any over which has less than four runs taken from it is considered as a very good over from that bowler, and it is shaded golden yellow, overs with four to six runs are deemed normal and it is shaded spring-green, six-ten runs over is considered expensive and is shaded steel blue, and any over in which more than 10 runs were scored is very bad and its shaded red.
4. Data Sources Pitch Map: Data Collected from cricket match videos Wagon wheel: Data Collected from cricket match videos Manhattan chart: Data Collected from cricket match videos 6. References E.R.Tufte. The Visual Display of Quantitative Information. Graphics Press, Cheshire, CT, 1990 P.Rheingans. Color Change, and Control for Quantitative Data Display. In Proceedings of Visualization 92 pp. 252-259, IEEE Computer Society Press Los Alamitos, CA, 1992 A.J.Fuller and M.L.X dossantos Computer Generated Display of 3D vector Fields Computer Aided Design 12(2):61-66, 1980 The Visualization Toolkit User's Guide By William J. Schroeder, Kenneth M. Martin, Lisa S. Avila, C. Charles Law Curves and Surfaces for CAGD: A Practical Guide by Gerald Farin The C++ Programming Language (Special 3rd Edition) by Bjarne Stroustrup Effective C++: 50 Specific Ways to Improve Your Programs and Design (2nd Edition) by Scott Meyers Effective STL: 50 Specific Ways to Improve Your Use of the Standard Template Library by Scott Meyers
7. Reference URLS http://www.channel4.com/sport/cricket/analyst/hawkeye/about.html http://www.channel4.com/sport/cricket/analyst/hawkeye/index_2001.html