Hi, I don't know what this is supposed to do, but I get pretty bad migraines and loading the page made me feel extremely strange almost immediately so I closed it.
I would check to make sure this can't trigger migraines or seizures. Maybe it's just me, but also, please double check.
I don't usually have headache migraines but do have strong visual auras from time to time.
Looking at this it first looked fun: "whoa, that's cool, this fovea thing is really smaller than I imagined"
After a minute or so playing around I closed the window and then I noticed a form
of retina persistence that looked eerily similar to an onset of a visual
aura, as well as some faint but clear ear ringing, both typical symptoms of the migraines I experience.
I immediately walked away from the computer and although dwindling it's still in effect 10min out.
Yes, immediately felt weird and a bit uncomfortable. I can almost see, or kind of sense, all those parts moving in the image even though I can only see the movement clearly in the center. I can easily imagine getting a headache from watching that for a longer time.
Interesting, I wonder.. have you ever tried a VR headset? Does that cause you migraines as well? or maybe any other discomfort that'd prevent you from using it?
Fascinating. I get very different results depending on which glasses I use.
I'm far-sighted with a relatively weak prescription.
Without glasses I have a tiny bit of lazy eye, it's not really perceptible for the most part looking at me, but for stuff like this I get a sort of figure-eight shaped blob of motion that skips around a fair bit which I guess is because my eyes fail to track correctly and can't find anything to focus on. Can't perceive the motion outside of this area.
With my regular glasses this there's still some of this effect, but much less pronounced. Can't see any motion outside of the center of my field of view.
With my reading/screen glasses, which technically makes me myopic, I get a large perfect circle, and can still detect a lot of motion outside of the circle, even if it's "low FPS".
The strength of the glasses alters the size of the image that lands on your retinas. More (-) means a smaller image thus you stop seeing movement much closer to the focal point.
Shadertoy got hugged to death by this shader a few years ago and it had a custom "please go away" banner for a little while. Funny seeing it show up again on HN front page.
That's pretty cute. IQ's a good guy, he's had every opportunity over the years to monetize Shadertoy but it's stayed free and true to its purpose for 12y now.
It's important to point out that all of the crosses are rotating, so this is effectively showing which parts of your vision are susceptible to change blindness (which is effectively 99% of it).
It's not possible to smoothly move your eyes unless you are tracking a moving object. Your eyes always move in saccades (quick jerky movements), unless there is a smoothly moving object, in which case your eyes gain the ability to track it smoothly.
woah its incredible how quickly i can spot the fuzzy spot around where i can clearly see the rotation, and when i unfocus can see fuzzy movement all around.
This is really cool. So this is the theory beind foveated rendering/streaming
Most of what you think you are seeing at any moment is only imagined.
The retina is not uniform. Most photosensitive cells (cones) are near the centre of vision. Peripheral vision has little resolving power. Can't make out fine details. The reality of this is much more extreme than it subjectively feels like. The eye doesn't actually have pixels but if it did they'd all be focused at the centre. Like an image where 10% of the area in the middle had 80% of the pixels.
At the centre of vision the eye has enough resolving power to make out the tiny star shapes and see that they are rotating. Outside of that narrow zone in the peripheral vision they're perceived as coloured blobs, at best. Normally your brain would make this transparent to you. But this is an unusual pattern. Your visual cortex doesn't realize all the stars should be rotating. So only the ones you can actually see at any one instant seem to rotate.
Try to look at an object in the room with you, such as a lamp, without looking at it directly. Observe it out of the corner of your eye. The more you try, the less sharply defined it will seem. At the very edge of your vision you're only getting a handful of pixels worth of colour information. But because you know it is a lamp, it has the sharpness of a lamp's definition even though you cannot actually see that definition without directly looking at it. That's a related illusion.
This is why the eye scans constantly in those micro-jerking motions known as saccades. If a face were to pop up on your display, it would feel like a single instant recognition of a person. But before you experience that the eye would scan over the eyes, mouth, nose and so on, several times, in sharp flicking motions, over about 100 milliseconds, and these dozen or so little snapshots, as it were, would be stitched together into the whole image of a face. Even though only a tiny slice of the eye, or the nose, etc. can actually be seen at any one time, you perceive the whole face.
This illusion hacks that and reveals how narrow our high-resolution vision really is. The whole visual field feels rather high resolution. But only that tiny spot where they rotate actually is.
You can see everything in your field of vision, but the area DIRECTLY in the centre has the highest level of detail. This image has high frequency animated details that are not cognisized equally by your entire FOV. The animated bit right in the middle at any given time is where your brain processes the most detail and also where you are looking.
At the default scale of 90, I can't see anything spinning at all even with the video full screen. If I set the scale to 250 or larger I can see the stars spinning, but I just see the whole field spinning. Even if I get so close to the screen it almost fills my field of vision.
So for me either the stars are too small to see any motion, or I can see them all spinning no matter what.
If I set the scale value (150) to roughly the ppi of my screen (4k 27"), I can see the effect.
You should see the rotating stars only in a small field of view (fov) where your eyes are focused and all other stars should seem to remain still.
A fully psychometric version of this that explores more than just the fovea could be created by varying the scale parameter (if you crank it up high enough you can see the movement in the periphery). The additional component you would need is to have trials where the subjects has to report whether a particular region (could even be cued with a red circle, I don't think it needs to be random) is actually moving or not while fixated on the center. There are clearly cells that detect this kind of motion in the periphery but they need larger visual input, possibly because the receptive fields of the cells that feed in are larger out there.
I can't see any movement, at any distance. How likely is it something weird with my vision vs. something weird with my monitor/computer? I'm on a 360hz monitor at 2k.
This is quite cool, rocked back and forth from and to my screen and got a (bit inconsistent, but consistently visible) "shape" of the fovea. maybe 30% larger than I thought it'd be!
Right after though, I felt like my vision was clouded, like there was a grey overlay on it or something for a few minutes. Don't recommend having this open for too long. Visual cortex doesn't like running against its limits I guess
That's how small the high quality input to your neural network is.
All your smart neurons start their inputs there (let's skip hearing for a moment). Every time you did math it worked on neurons with their roots at this small bunch in the visual cortex.
It's a tool for reusing training data. When you move your eyes around same neurons are fed new data samples.
It's basically same trick that convolutional neural nets use.
Oh wow, this made me realize something I've had for 20 years: When I look too close for a few seconds, I get blurriness at the center of my vision. It goes away after a while, but this made me realize that the blurry region is actually my fovea!
I have no idea why my fovea blurs when I look close up at something, and doctors haven't been able to figure it out, but at least now I can google it better.
I have nystagmus (rapid, uncontrollable, rhythmic eye movements), so I couldn't see anything at first, just lots of small dots.
I had to zoom in (Mac accessibility tool) but then I could see the effect briefly. My eyes go everywhere, but I could see patches of moving shapes with stationary shapes further away, only that the patch moved around a lot!
The idea is to look at the scene and observe which crosses are rotating. You will notice that in your peripheral, the crosses appear not to rotate (although they are, and you can check that by focusing on them). This gives you an idea of how large your fovea is.
On a retina Mac I had to double the scale value to get reasonable results.
Awesome. You'll see the little stars rotating only in the area they reach your fovea, the most sensible part of the retina. All the rest will not be able to perceive any motion.
No, there should be a shader (think video) rendered showing a bunch of tiny spinning things. Something went wrong when you tried to load the page. It's an optical illusion where only things close to the centre of your vision look like they are spinning and everything else looks still.
on my phone at typical distance and 90 scale i only see about an asprin tablet size area spinning. but at 180 scale i see almost everything spinning at same distance.
i think peripheral vision is quite sensitive to movement/contrast changes, but the moving shapes have to be large enough to trigger those receptors?
Just to be clear, we don't actually know what that does right? Like, there's no link to this making up for poor sleep or improving your cognitive function right?
TL;DR it helps you identify the true diameter of your visual focus, which is said to shrink with old age (mine shrinks more in terms of _time_ dimension but that's a different issue!)
For best results, use it _fullscreen_, change the #define `90` values to a higher value if you're on a high dpi screen.
Stare at a few places on the screen and you'll get the effect of appearing to rotate only where you stare.
Arete314159|3 months ago
I would check to make sure this can't trigger migraines or seizures. Maybe it's just me, but also, please double check.
lloeki|3 months ago
Looking at this it first looked fun: "whoa, that's cool, this fovea thing is really smaller than I imagined"
After a minute or so playing around I closed the window and then I noticed a form of retina persistence that looked eerily similar to an onset of a visual aura, as well as some faint but clear ear ringing, both typical symptoms of the migraines I experience.
I immediately walked away from the computer and although dwindling it's still in effect 10min out.
nkrisc|3 months ago
irilesscent|3 months ago
Edit: seems like there isn't enough research to suggest the latter. Apologies
kalaksi|3 months ago
Fabricio20|3 months ago
sho_hn|3 months ago
marginalia_nu|3 months ago
I'm far-sighted with a relatively weak prescription.
Without glasses I have a tiny bit of lazy eye, it's not really perceptible for the most part looking at me, but for stuff like this I get a sort of figure-eight shaped blob of motion that skips around a fair bit which I guess is because my eyes fail to track correctly and can't find anything to focus on. Can't perceive the motion outside of this area.
With my regular glasses this there's still some of this effect, but much less pronounced. Can't see any motion outside of the center of my field of view.
With my reading/screen glasses, which technically makes me myopic, I get a large perfect circle, and can still detect a lot of motion outside of the circle, even if it's "low FPS".
iNic|3 months ago
[1] https://en.wikipedia.org/wiki/Chromostereopsis
davidhs|3 months ago
Taterr|3 months ago
https://web.archive.org/web/20210430091013/https://www.shade...
joenot443|3 months ago
smusamashah|3 months ago
This is a flickering blue/green image. In the center wherever your eyes are looking, you will see a dark spot.
ludicrousdispla|3 months ago
pixelpoet|3 months ago
AbuAssar|3 months ago
ladon86|3 months ago
https://www.shadertoy.com/view/tXSBWt
Here is a version with a smoothly moving red circle; notice how you can now move your eyes smoothly around the screen as you track the circle.
Anamon|3 months ago
https://www.shadertoy.com/view/WdlGzl
svdr|3 months ago
qwertytyyuu|3 months ago
unknown|3 months ago
[deleted]
smusamashah|3 months ago
BriggyDwiggs42|3 months ago
retrac|3 months ago
The retina is not uniform. Most photosensitive cells (cones) are near the centre of vision. Peripheral vision has little resolving power. Can't make out fine details. The reality of this is much more extreme than it subjectively feels like. The eye doesn't actually have pixels but if it did they'd all be focused at the centre. Like an image where 10% of the area in the middle had 80% of the pixels.
At the centre of vision the eye has enough resolving power to make out the tiny star shapes and see that they are rotating. Outside of that narrow zone in the peripheral vision they're perceived as coloured blobs, at best. Normally your brain would make this transparent to you. But this is an unusual pattern. Your visual cortex doesn't realize all the stars should be rotating. So only the ones you can actually see at any one instant seem to rotate.
Try to look at an object in the room with you, such as a lamp, without looking at it directly. Observe it out of the corner of your eye. The more you try, the less sharply defined it will seem. At the very edge of your vision you're only getting a handful of pixels worth of colour information. But because you know it is a lamp, it has the sharpness of a lamp's definition even though you cannot actually see that definition without directly looking at it. That's a related illusion.
This is why the eye scans constantly in those micro-jerking motions known as saccades. If a face were to pop up on your display, it would feel like a single instant recognition of a person. But before you experience that the eye would scan over the eyes, mouth, nose and so on, several times, in sharp flicking motions, over about 100 milliseconds, and these dozen or so little snapshots, as it were, would be stitched together into the whole image of a face. Even though only a tiny slice of the eye, or the nose, etc. can actually be seen at any one time, you perceive the whole face.
This illusion hacks that and reveals how narrow our high-resolution vision really is. The whole visual field feels rather high resolution. But only that tiny spot where they rotate actually is.
shrinks99|3 months ago
cornonthecobra|3 months ago
So for me either the stars are too small to see any motion, or I can see them all spinning no matter what.
What effect am I supposed to see?
tspng|3 months ago
yreg|3 months ago
> What effect am I supposed to see?
I can see only a tiny area in the center of my vision animate (at default scale). The larger the scale, the bigger the area.
wartywhoa23|3 months ago
UPDATE: And yep, there (mostly) is! https://www.shadertoy.com/embed/4dsXzM?gui=false&paused=fals...
tgbugs|3 months ago
danielvinson|3 months ago
koolala|3 months ago
maxlin|3 months ago
Right after though, I felt like my vision was clouded, like there was a grey overlay on it or something for a few minutes. Don't recommend having this open for too long. Visual cortex doesn't like running against its limits I guess
scotty79|3 months ago
All your smart neurons start their inputs there (let's skip hearing for a moment). Every time you did math it worked on neurons with their roots at this small bunch in the visual cortex.
It's a tool for reusing training data. When you move your eyes around same neurons are fed new data samples.
It's basically same trick that convolutional neural nets use.
willbicks|3 months ago
cachius|3 months ago
NKosmatos|3 months ago
stavros|3 months ago
I have no idea why my fovea blurs when I look close up at something, and doctors haven't been able to figure it out, but at least now I can google it better.
dalmo3|3 months ago
xfz|3 months ago
I had to zoom in (Mac accessibility tool) but then I could see the effect briefly. My eyes go everywhere, but I could see patches of moving shapes with stationary shapes further away, only that the patch moved around a lot!
sd9|3 months ago
On a retina Mac I had to double the scale value to get reasonable results.
antirez|3 months ago
burnt-resistor|3 months ago
hekkle|3 months ago
"Bad request"
am I missing the joke?
gpm|3 months ago
astroflection|3 months ago
zdc1|3 months ago
ge96|3 months ago
oh I see fovea
altairprime|3 months ago
avidiax|3 months ago
jchw|3 months ago
zamadatix|3 months ago
leeoniya|3 months ago
on my phone at typical distance and 90 scale i only see about an asprin tablet size area spinning. but at 180 scale i see almost everything spinning at same distance.
i think peripheral vision is quite sensitive to movement/contrast changes, but the moving shapes have to be large enough to trigger those receptors?
not sure what to conclude from this.
herodotus|3 months ago
dotancohen|3 months ago
intrasight|3 months ago
zeckalpha|3 months ago
pacoverdi|3 months ago
https://www.paulkeeble.co.uk/posts/cff/
rosstex|3 months ago
Just to be clear, we don't actually know what that does right? Like, there's no link to this making up for poor sleep or improving your cognitive function right?
smallnix|3 months ago
wartywhoa23|3 months ago
unknown|3 months ago
[deleted]
keyle|3 months ago
For best results, use it _fullscreen_, change the #define `90` values to a higher value if you're on a high dpi screen.
Stare at a few places on the screen and you'll get the effect of appearing to rotate only where you stare.
It's pretty neat.
VeritySage07|3 months ago
[deleted]
rana762|3 months ago
[deleted]
theturtle|3 months ago
[deleted]
imcritic|3 months ago
[deleted]
MintPaw|3 months ago
https://x.com/iquilezles/status/1977172864785957340 https://x.com/iquilezles/status/1976866381099679817 https://x.com/iquilezles/status/1838858759336267842
shadowgovt|3 months ago