Channel 9 finally bow to benchmark00 pressure

[andyc]

I'm pretty sure the laws of the game mean the umpires should assume that the ball goes "straight on" after impact ie. no unusual swing or dip.

Pretty sure it's just that the umpires don't assume the ball is going to do anything it hasn't done yet, ie. if you get hit on the toe by what looks like a ripping legbreak, the umpire assumes it won't spin even though it probably would've.

Don't think that's what benchmark was really asking TBF, more just how does the system take into account something unexpected, say some late swing right before impact.

 

[Jono]

Don't think that's what benchmark was really asking TBF, more just how does the system take into account something unexpected, say some late swing right before impact.

Yeah that's how I interpreted it.

 

[Meridio]

Would imagine that the predicted path is based on the rate of change of position of the ball at the point closest to impact, not just a simple method of taking the release, bounce and impact positions and extrapolating it by treating the ball as a projectile. So your Hawkeye cameras (there's about 10 setup around a ground IIRC) record the delivery, and for each camera frame (I think they're 500 fps cameras) the system plots the position of the ball in relation to a fixed point (say the stumps) by comparing the measurements from the different cameras. This gives you an x, y, z position for the ball at each frame, you then have an algorithm that works out the change in x, y, z from frame to frame (and probably also the change in the rate of change) and extrapolates that from the frame you have closest to the point of impact. That way, you're taking any late movement into account.

I remember giving this quite a lot of thought a few months ago, actually applied for a job with Hawkeye. Got nowhere though, useless ****s didn't even respond to my application.