
A New Algorithm Reveals the Hidden World of Imperceptible Motion - 3eto
http://motherboard.vice.com/read/a-new-algorithm-reveals-the-hidden-world-of-super-tiny-movements
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walterbell
The special effects team on Ex-Machina overlaid graphics onto the actor. There
were scenes where the actor was "motionless" but they observed that the
emotional experience of the film required animated overlaid motion to match
the actor.

[http://www.theverge.com/2015/5/8/8572317/ex-machina-movie-
vi...](http://www.theverge.com/2015/5/8/8572317/ex-machina-movie-visual-
effects-interview-robot-ava)

 _" We also put a lot of effort into things like the muscles contracting
properly, and the various pipes and wiring having just a tiny amount of
jiggle. And it’s something that you really do not notice. But I remember when
we were looking at shots, for whatever reason when we put a shot through to
render overnight that secondary animation hadn’t rendered properly, so it was
missing. And everything suddenly felt very stiff. And you kick the shot off
again, this time with that animation integrated into it, and it works again.
It’s not something that you can necessarily put your finger on as being wrong,
but if it’s missing then you suddenly feel that something’s strange."_

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cat9
Here's another video of the algorithm being tested against a wider range of
targets.

[https://www.youtube.com/watch?v=AGA6eJXZAOw](https://www.youtube.com/watch?v=AGA6eJXZAOw)

The ability to pick up saccades could have interesting HCI implications if the
signal is consistent.

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rwinn
It would be interesting (and probably very funny) to apply this to a video of
a person trying to stand as still as possible.

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raverbashing
I remember a similar technique (maybe it's from the same people) where they
amplified color changes.

So the tiny flushes caused by the heartbeat were clearly visible

[https://www.youtube.com/watch?v=ONZcjs1Pjmk](https://www.youtube.com/watch?v=ONZcjs1Pjmk)
(from 1m30s)

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Sniffnoy
Yup, Durand and Freeman worked on both. The Eulerian video magnification isn't
just limited to color changes, of course, as the video shows. This new
technique is still based on Eulerian magnification, if I understand correctly.

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ddeck
Interesting talk by one of the researchers on the techniques including
recovery of audio from video of passive object vibrations:

[http://www.ted.com/talks/abe_davis_new_video_technology_that...](http://www.ted.com/talks/abe_davis_new_video_technology_that_reveals_an_object_s_hidden_properties)

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joshu
If you realize that a camera is a time-series motion capture sensor, as is a
microphone (the position of the diaphragm) then this is actually less
relevatory...

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teej
Honest questions: how many "frames per second" is a standard microphone? What
exactly is a "frame" of audio?

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WiseWeasel
44.1 kHz (CD quality audio) is 44,100 samples per second, though professional
recording equipment typically supports up to 96 kHz sample rates.

Note that for the more common analog microphones, the microphone itself
doesn't determine the sample rates; it's the digital sampler to which it's
connected.

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raverbashing
"the microphone itself doesn't determine the sample rates"

True, but it has a response curve, and I assume most don't respond as well to
>20kHz frequency (or even less)

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callesgg
That motion was not Imperceptible.

The video that @raverbashing mentined seams to be much more useful.

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Sniffnoy
That's an older technique that this is based on -- the one that, as mentioned,
can't handle both large and small motions. Given that, I wouldn't compare it
by that one example.

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EGreg
How does it compare to Eulerian Video Magnification?

[http://newsoffice.mit.edu/2012/amplifying-invisible-
video-06...](http://newsoffice.mit.edu/2012/amplifying-invisible-video-0622)

~~~
Sniffnoy
That's the older technique that this is based on. See the actual paper:
[http://www.cv-
foundation.org/openaccess/content_cvpr_2015/pa...](http://www.cv-
foundation.org/openaccess/content_cvpr_2015/papers/Elgharib_Video_Magnification_in_2015_CVPR_paper.pdf)

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stevep98
I can imagine this being useful to show how buildings and bridges move in the
wind or earthquakes. Could be quite alarming though.

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RobotCaleb
What is this sort of thing typically used for?

