Luckily for everyone, I'm a sports engineer and not an
England International.
But I'd love to measure exactly what's going on when
our International footballer takes a penalty under those
extreme tournament conditions.
Here in the biomechanics lab, we can take accurate
measurements of movement.
The cameras and lights are on, I'm wearing my black suit,
I've got passive markers all over me.
I can sort of visualise the goal in the distance, but the
problem is it's just not that realistic.
It's like that problem in quantum mechanics: the act of
measuring something changes it.
What we really want is a cheap system that we can use out in
the field that measures the player without
changing what he does.
One way of doing that is to take a video of a sporting
performance.
And here we have a greyscale video of a single tennis shot
during a game.
We've tracked the ball, and we can look at the brightness of
the pixels surrounding the ball with time.
And that gives us information on speed, spin, and angle of
that shot, all with a single camera.
Now that's great, but it takes a lot of number crunching, and
we can only get the answer after the performance.
And as we've seen with our previous film on diving, we
really want instantaneous feedback.
And what about bigger and more complex sports like football?
Like any good engineer, we've been looking at the tools for
a solution, and we've been exploring a piece of
technology from a very different source of game, the
Xbox Kinect.
John, you've been working on the Kinect sensor for 18
months, and this is the first time we've had the opportunity
to plug it into an Xbox and play a game with it.
Tell me how it works.
Obviously, for us to be able to play this game, what the
Kinect's doing is working out where we are in three
dimensions.
And the way that it does that is an infrared projector on
the sensor sends out a speckled pattern of infrared
dots into the scene, and compares the image that it
gets from its infrared camera to an image that's stored on
the device.
And the differences between those two images tell the
Kinect not only where we are in the image plane, the
horizontal distances, but where we are in terms of depth
away and towards the Kinect.
In the lab here we've got a really expensive bit of kit
that does exactly the same thing, but costs
1,000 times as much.
So please tell me that we haven't wasted our money.
Well, the accuracy of the Kinect looks pretty good.
We might be interested in the location of a badminton player
on a court, for example.
So we can locate the player to around about 5 to 10
centimetres of error, which, in the context of the size of
the badminton court, is pretty good.
But for finer measurements, the sort of measurements that
we might take in here with this system, we might be
interested in measuring joint angles or the positions of
body segments, we're not getting the levels of accuracy
that we would see in the lab.
But the benefit of the Kinect is that it's cheap.
It's essentially a commodity item, and we can take the
Kinect out and take measurements in the field, on
a player's badminton court, and essentially where they're
performing.
How long before we have one of these out on a football pitch?
It's difficult to say, because the drivers for this
technology have obviously been the sort of thing that
normally happens in a living room, over quite small areas.
So it's difficult to know what the drivers will be for the
development of the technology to work over larger areas.
Whoa.
Who's winning?
I have no idea, Steve.
We can take accurate measurements within the
laboratory, but we're really constrained by the
environment.
Where we'd really like to be is out here in the field
taking measurements of the reality of our athletes.
Now that's a tremendously challenging thing to do, but
with image processing techniques, with high
definition cameras, with depth cameras, combined with mobile
technologies, I think we're on the verge of
being able to do that.
And for a sports engineer, that's tremendously exciting.