

Computer Graphics?  Or Real?  "Ultimate Batting Practice" (video) - ColinWright
http://www.youtube.com/watch?v=W8SK0rk5jdE

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ColinWright
I wouldn't normally submit something like this. It's not "deeply interesting"
and it's not technical, but I was watching it and thinking - computer
graphics?

But I can't see how it _can_ be fake, unless the ability of the software these
days is significantly beyond what I thought. So I figured I'd ask the
community I have contact with that's likely to know the most about it.

And that's HN.

So I ask: Is it for real?

~~~
anigbrowl
Film guy here. It wouldn't be that hard to fake. angle of the sun/direction of
shadow is easy to keep consistent, motion blur is wholly automated these days
(as in, select start/end frame & position, and motion blur will be on by
default in most programs with excellent results). Although the camera is
moving slightly, the distinctive and structured shapes of the batting nets
provide perfect tracking points for trajectory mapping; alternatively, you
could shoot at a higher resolution from a tripod and then introduce some
floaty movement afterwards, windowing onto a smaller frame at 1:1 resolution.
Making the nets bounce is trivial, you just need a couple of takes from the
same camera position. As long as the light isn't changing, it's astonishingly
easy to key stuff in and out from different frames - typically used to remove
people or vehicles, but just as easy to introduce them. So it's possible that
this is a film school/enthusiast project; I'd say it could be done in a single
day on an average workstation.

On the other hand, the guy may just be a good batter. Bouncing a ball off 4
nets will rob it of a lot of speed, and if one practices a lot it's not that
hard to get a rhythm going. When I was a teenager I used to kick a soccer ball
off a wall for practice, and my aim was kick it back 100 times, starting over
from 0 if I lost it. I wasn't all especially good or dedicated, so I have no
problem believing this would be achievable by someone who's serious about the
sport. Jugglers have to perform far more complex movements at much faster
speeds, for that matter. Finally, for all we know this could have been the
10th or greater attempt to pull this off.

So either is possible. I don't feel like downloading the video and stabilizing
it to do a windowed frame diff, but if you wanted to get forensic on its ass
the best place to start would be to measure the # of frames between hits,
because you're got a nice marker from the noise of the bat; if it's exactly
the same more than 3 times in a row suspect a fake, likewise if you see a
repeating progression of frame intervals like 23-25-24-23-25-24.

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ColinWright
Follow-up: <http://news.ycombinator.com/item?id=2878992>

Conclusion: it's a fake.

