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My colleagues and I are fascinated
by the science of moving dots.
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So what are these dots?
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Well, it's all of us.
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And we're moving in our homes,
in our offices, as we shop and travel
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throughout our cities
and around the world.
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And wouldn't it be great if
we could understand all this movement?
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If we could find patterns and meaning
and insight in it.
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And luckily for us, we live in a time
where we're incredibly good
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at capturing information about ourselves.
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So whether it's through
sensor,s or videos, or apps,
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we can track our movement
with incredibly fine detail.
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So it turns out one of the places
where we have the best data
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about movement is sports.
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So whether it's basketball or baseball,
or football or the other football,
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we're instrumenting our stadiums
and our players to track their movements
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every fraction of a second.
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So what we're doing is turning our
athletes into -- you probably guessed it
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moving dots.
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So we've got mountains of moving dots
and like most raw data,
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it's hard to deal with
and not that interesting.
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But there are things that -- for example
basketball coaches want to know.
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And the problem is they can't know them
because they'd have to watch every second
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of every game, remember it
and process it.
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And a person can't do that...
but a machine can.
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The problem is a machine can't see
the game with the eye of a coach.
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At least they couldn't until now.
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So what have we taught the machine to see?
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So, we started simply.
We taught it things like passes,
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shots and rebounds.
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Things that most casual fans would know.
And then we moved on to things
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slightly more complicated.
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Events like post-ups,
and pick-and-rolls, and isolations.
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And if you don't know them, that's okay.
Most casual players probably do.
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Now, we've gotten to a point where today,
the machine understands complex events
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like down screens and wide pins.
Basically things only professionals know.
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So we have taught a machine to see
with the eyes of a coach.
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So how have we been able to do this?
If I asked a coach to describe something
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like a pick-and-roll, they would
give me a description and
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if I encoded that as an algorithm,
it would be terrible.
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The pick-and-roll happens to be the stance
in basketball between four players,
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two on offense and two on defense.
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And here's kind of how it goes.
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So there's the guy on offense without
the ball and he goes next to the guy
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guarding the guy with the ball,
and he kind of stays there
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and they both move and stuff happens,
and ta-da, it's a pick-and-roll.
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(Laughter)
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So that is also an example of
a terrible algorithm.
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So, if the player who's the interferer
-- he's called the screener,
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you know, goes close by,
but he doesn't stop.
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It's probably not a pick-and-roll.
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Or if he does stop,
but he doesn't stop close enough,
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it's probably not a pick-and-roll.
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Or, if he does go close by
and he does stop but they do it
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under the basket,
it's probably not a pick-and-roll.
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Or I could be wrong.
They could all be pick-and-rolls.
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It really depends on the exact timing,
the distances, the locations
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and that 's what makes it hard.
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So, luckily with machine learning
we can go beyond our own ability
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to describe the things we know.
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So how does this work?
Well, it's by example.
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So we go to the machine and say,
"Good morning, machine."
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"Here are some pick-and-rolls,
and here are somethings that are not."
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"Please find a way to tell a difference."
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And the key to all of this is to find
features that enable it to separate.
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So if I was trying to teach it
the difference between an apple and orange,
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I might say, "Why don't you use color,
or shape?"
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And the problem that we're solving is,
what are those things?
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What are the key features that let a
computer navigate the world of moving dots?
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So figuring out all these relationships
with relative, absolute, location,
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distance, timing, velocities.
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That's really the key to the science
of moving dots, or as we like to call it
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spatiotemporal patter recognition,
in academic vernacular.
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Because the first thing is,
you have to make it sound hard
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and... because it is.
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The key thing is for NBA coaches,
it's not that they want to know
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whether a pick-and-roll happened or not.
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It's that they want to know how it happened.
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And why is it so important to them?
So here's a little insight.
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It turns out in modern basketball, this
pick-and-roll is perhaps
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the most important play.
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And knowing how to run it,
and knowing how to defend it,
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is basically a key to winning
and losing most games.
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So it turns out that the stance has
a great many variations
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and identifying the variations are really
the things that matter,
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and that's why we need it to be
really, really good.
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So, here's an example.
There's two offensive players
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getting ready to do the pick-and-roll dance.
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So the guy with ball can either take,
or he can reject.
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His teammate can either roll or pop. The
guy guarding the ball can go over or under.
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His teammate can either show
or play up to touch, or play soft
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and together they can either
switch or blitz
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and I didn't know most of the things
when I started and it would be
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lovely if everybody moved according to
those arrows.
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It would make our lives a lot easier,
but it turns out movement is very messy.
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People wiggle a lot and getting these
variations identified with very, very
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high accuracy, precision and recall
is tough because that's what it takes
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to get a professional coach
to believe in you.
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And despite t