h a l f b a k e r yInexact change.
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Center the target in your screen, and touch "Go". The flash fires an
improbably-short and incredibly-bright blip, while the camera
records
at a frenetic frame rate. The video actually catches the reflections
of
the flash coming back from near objects first, then further-away
ones.
In slo-mo,
it looks like a lantern traveling down a hallway.
The software searches for the lighting-up of the center of the
screen,
and calculates distance from time. There is a slide to move back
and
forth in the vid, and a choice of units of distance.
Topical
http://gizmodo.com/...-path-at-1681990733
High-speed video of light pulse travel. [neutrinos_shadow, Mar 02 2015]
More
http://gizmodo.com/...f-a-mirr-1667133832
Light pulse bouncing. [neutrinos_shadow, Mar 02 2015]
Baked: Time-of-flight camera
https://en.wikipedi...me-of-flight_camera
[notexactly, Mar 02 2015]
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Yeah, I have no idea on the technology on this one. It fell out of
another idea, something about triangulating on target, in the unrestful
A.M. |
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I am sure it could be made to work, even if only for retro-reflectors in
the distant dark. Tweaking the flash to a recognizable series of blips
is all else that I have. |
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You think just detecting the pulse in the center pixels is all that is
needed? (It would have to ignore the flash going off, of course.) It
doesn't have to actually record vid - that was left over from trying to
not point at the target, plus I want to see a light pulse travel. |
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(It was something about two innocent-seeming tourists directing
mortar fire, I think.) |
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Consider the high speed recordings of bullet impacts and
the technique involved, then consider how that could be
done around 800,000 times faster. Hell, even 80,000 times
faster. That is the challenge you are proposing. |
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I know nothing about CCDs. Except maybe the name means "charge-
coupled device". |
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When I studied electronics, TVs still had tubes. I don't mean picture
tubes, I mean the clear, glowy things with all the funny metal bits in,
that, like, bounced the electrons or something. |
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Baked, many times over, by many companies, since about
15 years ago—see my link. |
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It does require special hardware, but it's getting cheaper
all the time and will be in smartphones in a few years.
(The LG G3 actually has a single time-of-flight sensor (not
a ToF camera) for focusing the camera for close-up
photos.) |
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Also, look at Ramesh Raskar's work in the computational
photography field. (You might remember the "1 million
fps" camera—that was him and his team. (It wasn't
actually 1 million fps; it used stroboscopy to synthesize
that framerate.) There was a popular demo video of that
device that showed light traveling along a water bottle in
slow motion,
which is the same concept.) |
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