AI gives batsmen insights
USING video only, artificial intelligence (AI) can now distinguish batters with a straight backlift from those using a lateral backlift, a technique by one of cricket legends Sir Donald Bradman that left the lovers of the game divided.
Thanks to University of Johannesburg (UJ) researchers who built the first deep-learning computer vision AI model to do this, coaches may give more detailed feedback to players using such technology or easily identify players with lateral backlift components in future.
The technique involves the batter initiating a very subtle movement in a split second just before a bowler releases the ball at the crease. This is when the batter starts moving their bat into position.
They select the shot depending on the format of the game and the type of bowler approaching them. Most fast bowlers tend to bowl at between 140 and 150km/h, said Professor Habib Noorbhai, director of the Biomedical Engineering and Healthcare Technology Research Centre at UJ.
He is also a sports scientist and has worked with local and international cricket teams since 2010.
His doctoral thesis was the first research to theorise the lateral batting backlift technique in cricket.
Another factor is the batter’s instincts and training. Will they bring up the bat straight with its face towards the ground or the stumps? Or will they angle the face of the bat outward towards the second slip or the wicketkeeper?
The researchers, Tevin Moodley, Prof Dustin van der Haar and Noorbhai all played cricket at school. Moodley, a doctoral student, used AI to recognise different batting strokes in previous research.
For this study, he focused on getting AI to do the subtle task of identifying batting backlift style.
“I was wondering if I can automate that process. Why does a coach have to think, Is that straight or lateral? If they know, they can say: ‘You have a lateral backlift, I can now help you in this manner,’” said Moodley.
Moodley had to find video footage for their AI to learn from, since no open datasets were available. He combed through online video footage of First-Class International Cricket Tests. He used the years 1995 to 2021.
From there he selected 11 batters with a straight backlift: Babar Azam, Temba Bavuma, Rahul Dravid, JP Duminy, Dean Elgar, Mahela Jayawardene, Ajinkya Rahane, Joe Root, Rory Burns, Ben Stokes and David Warner. And another 10 with a lateral backlift: AB de Villiers, Hashim Amla, Quinton de Kock, Faf du Plessis, Kevin Pietersen, Kumar Sangakkara, Brian Lara, Ricky Ponting, Steve Smith and Virat Kohli. Moodley manually selected 160 frames (images) from the video clips as the AI’s “training class”.
“I don’t think this research is about analysing more players. I think it is about providing coaches and players with more insight than they are currently getting,” said Noorbhai.