Imaging at a trillion frames per second! - Page 1
Forum section: electronics / general

author: Unknown
author_rank: Unknown
timestamp: August 22, 2012, 12:19:36 pm
content: "Ramesh Raskar presents femto-photography, a new type of imaging so fast it visualizes the world one trillion frames per second, so detailed it shows light itself in motion. This technology may someday be used to build cameras that can look "around" corners or see inside the body without X-rays."

author: bilko
author_rank: Frequent Contributor
timestamp: August 22, 2012, 02:24:41 pm
content: Ok, How long then to capture 1 trillion frames ?So not real time then ?BS and hype ...

author: Unknown
author_rank: Unknown
timestamp: August 22, 2012, 02:53:28 pm
content: Quote from: bilko on August 22, 2012, 02:24:41 pmHere is some more info.http://web.media.mit.edu/~raskar/trillionfps/Quotehehe. maybe "you're not thinking fourth-dimensionally" perhaps you can put that to Mr Rasker and his friends yourself. ;-)

author: poorchava
author_rank: Super Contributor
timestamp: August 22, 2012, 02:57:00 pm
content: I must say that this is amazing o.O

author: bilko
author_rank: Frequent Contributor
timestamp: August 22, 2012, 03:04:18 pm
content: Quote from: jucole on August 22, 2012, 02:53:28 pmHe is an animator, and that is all this is. Do you remember as a kid taking a book, drawing an image and on each sheet varying the image ?Then flick the pages and see the image move, it MAGIC, of course

author: edy
author_rank: Super Contributor
timestamp: August 24, 2012, 02:18:45 am
content: I believe the technique is not actually capturing 1 trillion frames consecutively. Instead, it is a clever way of "timing" repeatable shots where you shoot each subsequent image a trillionth of a second after the first. This can only be done by tracing the path of light because it is non-destructive to the objects in the scene.For example, imagine you have a machine gun shooting bullets through the air. You time your camera to shoot at progressively LONGER intervals after it hears a "bang" sound....So the first bullet it captures just barely exiting 1mm from the barrel. Then the second bullet it captures when it is 2mm out of the barrel, then the third bullet it captures when it is 3mm out of the barrel, and so on... You string all of the images together in a film and it APPEARS like you captured the same bullet exiting from the barrel at extremely fast frame rate. But it is actually 3 different bullets.Neat process! I wonder if we can rig something like this on EEVBlog! Dave, you have to try this! :-)

author: pickle9000
author_rank: Super Contributor
timestamp: August 24, 2012, 03:34:14 am
content: Of course instead or three bullets you could use three cameras, like a modern dso uses two or more capture devices. I'd really like to see what the guts of the camera looks like, math and post processing aside it would be very interesting to see how they are tackling the problem....mike

author: AntiProtonBoy
author_rank: Frequent Contributor
timestamp: August 24, 2012, 04:42:50 am
content: The technique uses a femtosecond pulsed light and a tunable shutter system to discriminate reflected light reaching the camera at a specific "time of flight" delay. For example, you send a light pulse into the scene. Light reflections from various surfaces in the scene will reach the camera at different times, depending on the total distance of each reflected path. You can discriminate photons from various parts of the scene by making the shutter open a narrow temporal window at a specific time delay after the light pulse. So this means that you can potentially record reflectance properties of materials that are not in direct line of sight of the camera and/or the light source (ie. "around the corner" of things).

author: Unknown
author_rank: Unknown
timestamp: August 24, 2012, 07:44:27 am
content: My guess, using Edy's analogy of the bullets; in order to collect enough light so the image is not dark, not only would they capture each bullet at each "hold-off" interval, I think they would use multiple "hold-off" passes in order to collect enough light information to reconstruct the appearance of a nicely light frame.

author: AntiProtonBoy
author_rank: Frequent Contributor
timestamp: August 24, 2012, 08:04:18 am
content: No need to guess, you can get some interesting info from their official website:http://web.media.mit.edu/~raskar/trillionfps/

author: amyk
author_rank: Super Contributor
timestamp: August 24, 2012, 08:16:40 am
content: On that site they make it very clear that this is an "effective" framerate. The word "effective" is like one of those "this is an amazing number to use for marketing but doesn't take into account all the other nontrivial issues with this process" disclaimer terms.See also: effective contrast rates in LCDs, effective resolutions in webcams, etc.An interesting process overall, but it does have quite severe limitations on what it can be used for.

author: TriodeTiger
author_rank: Regular Contributor
timestamp: August 24, 2012, 09:23:18 am
content: If it were very close to what you would see with femtosecond resolution, even if not, made my hair stand on end.Almost like seeing something you're not supposed to. In fact- you couldn't see, if it weren't for that light that you are seeing moving.