My theory is that the brain automatically 're-frames' the image when you move your eyes. Here's a point - the eyes never move smoothly unless tracking a moving object to keep it stationary within the field of vision. They always dart about. Cinema would not work if our eyes were digital, since the frame rate of our eyes would go out of sync with the pictures. Persistence of vision is why cinema works. Projectors (35mm) show each frame three times, so that there is no flicker to the image, so if there is a 'sampling rate' of the eye then it is certainly higher than the 72 flickers-per-second. Flourescent gas discharge lamps flicker, albeit at a very high speed, so this explains the aliasing effect. This is a great way of explaining aliasing (like cartwheels in a 'Western' movie) because the light is 'sampling' the bicycle wheel. My bicycle wheels are so buckled that this becomes very confusing to look at ;-)
Going back to the spectrum graphing amplitude problem - there should be a way to use peakit~ and build a graphical data structure-based array around its findings. I think data structures are the way forward for this sort of thing since they represent information in an abstract graphical way. examples/ekext/peakit-listmoses.pd (but there's no graphical array yet) Chun did a cool thing - it would be interesting to know how the video was made. Look up 'chun lee glass cloud' on youtube. Gem?
Best, Ed
On 10/22/07, Roman Haefeli reduzierer@yahoo.de wrote:
On Mon, 2007-10-22 at 17:33 -0500, Charles Henry wrote:
On 10/22/07, Martin Peach martin.peach@sympatico.ca wrote:
Mathieu Bouchard wrote:
A very simple way to explain aliased frequencies would be: spin
a bicycle
wheel. When you accelerate it beyond a certain point, it will
begin to look
like it's going backwards instead. This is because the wheel
speed,
together with the repetitiveness of the wheel's appearance, have
crossed
the Nyquist frequency of your eye.
That won't work in sunlight for example.
Haven't you ever seen it? (in sunlight that is)
As implied, I'm 99% positive I've seen it before. You might still be able to convince me that I haven't ;)
i think, that is the point that martin is trying to make.
i am not an expert either, but when i encountered this effect
(watching
the frontwheel, while cycling at night, for instance), there was
always
artificial light involved. to be more precise, there was always kind
of
a fluorescence or any other kind of 'gas discharge lamp' (is that the correct expression?) involved. it doesn't seem to work with common
light
bulbs, since their 'afterglow time' is too long.
for me, it seems, that it is rather related to the light source and
its
frequency and not to a property of the eye.
hey, what do you know, there's even a wiki page on it: http://en.wikipedia.org/wiki/Wagon-wheel_effect
Vision is in fact not purely analog. Although I don't necessarily think the "discrete frame" theory mentioned in the page is true, there is a counterexample. When your eyes make a saccade (fast movement), there is no blurring. There is an inhibition of the movement in between the two visual scenes. There is also nystagmus. Even when images appear perfectly clear, the eye moves in random oscillations. When researchers (I forget the citation/can't find it) used an eye camera to track random oscillations and corrected for the movement (creating a static retinotopic image), the perceived image disappears. There may be something involved in correcting for nystagmus that renders an image in a series of apparently still frames. I don't know for sure.
Chuck
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On 24/10/2007, at 13.33, Ed Kelly wrote:
Chun did a cool thing - it would be interesting to know how the
video was made. Look up 'chun lee glass cloud' on youtube.
On Wed, Oct 24, 2007 at 02:01:13PM +0200, Steffen Juul wrote:
On 24/10/2007, at 13.33, Ed Kelly wrote:
Chun did a cool thing - it would be interesting to know how the
video was made. Look up 'chun lee glass cloud' on youtube.
Wow, what an utterly wonderful piece of work! This is my new favorite video, thanks for sharing. I wish more people would post stuff like this to the pd-list.
Chun, I am really interested in what tools you used to make this. Has it been exhibited or screened anywhere?
Best,
Chris.
Hallo, Chris McCormick hat gesagt: // Chris McCormick wrote:
Chun, I am really interested in what tools you used to make this. Has it been exhibited or screened anywhere?
It was performed at Make Art in Poitiers this year. The video is not Pd, though: Chun's partner Oli uses Processing here. But Chun probably can say more about this...
Ciao
Frank Barknecht _ ______footils.org__
hi all:
thanks for asking about this music/visual. a few things that i should say/clarify about the visual.
the visual is made by one of my close collaborator called Oli (http://yesyesnono.co.uk), we perform quite regularly in london (under the name of cracktux) and whereever we get to play. and this is one of the track we played.
oli uses processing to make the visual and i use Pd to make the music.
we use a small custom software to do fft from sound so that oli can use it to make/drive the visual(hence the beginning of the glass cloud.)
this software is called Jackbytes, made by one of our friend (robert atwood) in OpenLab london. source is here: https://puredyne.goto10.org/listing.php?repname=jackbytes&path=%2Ftags%2...
Robert's site is usually robert.lurk.org, which is down atm:/
as far as i know, its a generic client/server app to get fft data from jack. in this case, the client is running for processing. but can be anything i think.
hope this is clear.
peace
chun
Chris McCormick said :
On Wed, Oct 24, 2007 at 02:01:13PM +0200, Steffen Juul wrote:
On 24/10/2007, at 13.33, Ed Kelly wrote:
Chun did a cool thing - it would be interesting to know how the
video was made. Look up 'chun lee glass cloud' on youtube.Wow, what an utterly wonderful piece of work! This is my new favorite video, thanks for sharing. I wish more people would post stuff like this to the pd-list.
Chun, I am really interested in what tools you used to make this. Has it been exhibited or screened anywhere?
Best,
Chris.
-
[*~] -
Chris McCormick -
Ed Kelly -
Frank Barknecht -
Steffen Juul