Wednesday, 18 May 2011

Photo Finish for FlyBall

I had never heard of Flyball until Dave contacted me a while back. He emailed me because he had a few questions about how best to proceed for his project.

Flyball is a dog sport in which teams of dogs race against each other from a start/finish line, over a line of hurdles, to a box that releases a tennis ball to be caught when the dog presses the spring loaded pad, then back to their handlers while carrying the ball. Flyball is run in teams of four dogs, as a relay. -Wikipedia

The dogs are really fast. The competitors are serious about performance. The race clock has 3 decimal digits, every fraction of a second counts. Getting a good timing when relaying the dogs is critical; Ideal running is nose-to-nose at the start line.

Dave had the idea of using Webcam Zone Trigger's motion detection system to generate a photo-finish at the start line, this could be used as a training tool to get better relay times. The main question was how to get reasonable images fast enough for a photo finish.

Most webcams can't get more than 30 frames per seconds. An exposure of 1/30th of a second makes for a blurry image when the dog is speeding by. First thing I suggested was to make sure there was a decent contrast between the dog and the background, this way the webcam would have a better chance. Good lighting will help in both the contrast and the camera's framerate.

We talked about which camera would do the job best. From my previous tests, I knew that a USB DSLR camera would not release fast enough, so I recommended against that. Since Zone Trigger does the motion detection on live frames, it can save the exact frame on which is has detected motion, which is ideal. The issue was to find a camera that provides a stable and fast framerate.

Dave tried out the PS3 Eye camera, which has a driver available for Windows. It turns out that it provided some decent results. The images where blurry, not good enough to hang on your wall, but good enough to get reliable motion detection.

"I used Zone Trigger today to get some captures. From a trigger standpoint, it worked flawlessly. 100% reliable and no false triggers! That’s pretty amazing, given how fast the dogs are going (1 ft per 50 msec)." -Dave

Thank you, Dave, for the great project!
Go for the gold!