
The Math Behind the Rolling Shutter Phenomenon - soundsop
http://petapixel.com/2014/10/13/math-behind-rolling-shutter-phenomenon/
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chris_overseas
Excellent article.

I remember a few years back holding my mobile to the window to take a photo of
the scenery while on a turbo prop passenger aircraft. I nearly had a heart
attack when I noticed the propeller had stopped spinning!

Once I got over the initial shock and realised it was just rolling shutter on
the phone screen I had a bunch of fun taking photos and videos of the effect
in action. I'll try and dig up one of the videos and post it here later.

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mikeash
It's especially fun when it's a helicopter and the camera is synchronized with
the rotor:

[https://youtube.com/watch?v=qgvuQGY946g](https://youtube.com/watch?v=qgvuQGY946g)

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semi-extrinsic
The rotor "freezing" is not caused by the rolling shutter, but by the rotor
speed being an integer multiple of the framerate. In fact, you can see in the
video you linked that the camera used does _not_ have a rolling shutter.

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mikeash
Isn't that also true of the comment I replied to, though?

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chris_overseas
Yes that's a very good point - the freezing of the blades is due to temporal
aliasing, not rolling shutter. Here's a link to a post I made about this that
includes a video showing both temporal aliasing and rolling shutter in action:
[https://plus.google.com/+ChrisMiller/posts/iAfeK4D7E9B](https://plus.google.com/+ChrisMiller/posts/iAfeK4D7E9B)

~~~
mikeash
That's wonderful, the combination of the two effects in that video is really
cool.

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OJFord
Excellent article. Presumably at least part of the problem toward the end is
that it's based on the assumption the propellor moves at a constant speed;
since the plane is not mid-flight, I would guess it's probably accelerating.

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jasmcole
Hi, I wrote this article about a year ago on my blog. Thanks for posting it!

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omershapira
Horizon, a game based on rolling shutter mechanics, but with geometry instead
of pixels:
[http://omershapira.com/portfolio/horizon-a-4d-game/](http://omershapira.com/portfolio/horizon-a-4d-game/)

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bharath28
Wow. Terrific post- it is finding these kind of Gems that keeps me coming back
to HN.

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DanBC
Here's some information about a different type of shutter, and camera, and
imaging technology:
[http://www.largeformatphotography.info/forum/showthread.php?...](http://www.largeformatphotography.info/forum/showthread.php?31903-Jacques-
Henri-Lartigue-and-his-camera)

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clebio
previous discussion (such as it was):
[https://news.ycombinator.com/item?id=8475255](https://news.ycombinator.com/item?id=8475255)

