Heat seeker

Whether it’s the PlayerCam that follows individual footballers over the course of a match, or the Hawk-Eye system used to predict the trajectories of cricket, tennis and, most recently, snooker balls, TV sports viewers are frequently the first to be exposed to hi-tech broadcasting innovations.

In a fascinating and unusual tale of technology transfer, the latest broadcasting device to enrich the armchair fan’s viewing experience is based on a system more commonly found on armoured tanks and fighter jets.

Hot Spot, unveiled by Sky Sports during the summer’s first test match between England and the West Indies, uses powerful infrared cameras to detect the distinct thermal signature left when a cricket ball hits a pad, clips the edge or flies off the middle of the bat.

Developed by BBG Sports — the small Australian firm behind the ‘snickometer’ and the speed gun — Hot Spot uses two powerful thermal imaging cameras positioned above the field of play at opposite sides of a ground. These devices, which can be up to 90m away from the action, remotely sense and measure the tiny amount of heat generated by the collision of a cricket ball and then create a black and white negative image which shows the ball’s precise point of contact.

Talking to the Engineer from Headingly ahead of last month’s second test match, BBG’s Warren Brennan explained how the system was developed: ‘We came across the technology about four years ago and thought it was quite interesting. We sat down and thought about whether we could apply it to different sports and cricket is the first one we’ve done.’

Brennan and his team evaluated a number of different systems before settling on the core element of Hot Spot system: a military standard Emerald LR infrared camera manufactured by French imaging specialist CEDIP. ‘We started off with standard hand-held cameras of the type that electrical contractors use to look at electrical circuits, but they didn’t do the job. So we moved up to the next stage and finally got up to the top-end military stuff and started to get better results.’

The key to obtaining these results, said Brennan, was the use of so-called cooled cameras, where the sensitivity of the system is enhanced by an internal cooling system that maintains the infrared sensor at a low temperature. Brennan said that the Hot Spot application makes BBG sports one of the first customers for the cameras outside of the military sphere.

Unsurprisingly, buying military-grade equipment, modifying it, and then lugging it about all over the world is not exactly a straightforward process and BBG had to jump through a number of bureaucratic hoops to get the system off the ground. Indeed, before settling on the CEDIP system, the team was in discussions with a US company that is the only other manufacturer of thermal cameras with a high enough resolution. It was this company’s unwillingness to part with its technology that led Brennan to the French.