4 ms·

Relevant: You can actually perceive the rough size of your fovea with this optical illusion: https://www.shadertoy.com/view/4dsXzM https://www.shadertoy.com/vie

Relevant: You can actually perceive the rough size of your fovea with this optical illusion: https://www.shadertoy.com/view/4dsXzM https://www.shadertoy.com/view/4dsXzM

TeMPOraL 6y ago
Very interesting. I was wondering what determines the speed at which the stars in foveal vision rotate. I assumed the movement is the illusion, but it turns out the stars all rotate - there's an explicit parameter determining their period in the shader. The illusion is that the stars outside your central vision seem frozen!
- TemporalSux 6y ago
  Your comment can be summed up as “I’m retarded”. It just consists of you completely wasting everyone’s time by articulating the slow journey of yourself comprehending what everyone else understood at a glance. How would your computer know where you’re looking you stupid fuck? Haven’t you posted enough comments by now? You have over 79000 karma points on this site. What the fuck? Give it a rest so other people can be heard you fucking windbag.
janekm 6y ago
Weirdly for me the "size of the fovea" is much smaller with the windowed view than fullscreen (seems to be the same proportion of the overall image), which doesn't seem to make sense. Perhaps another optical illusion is in effect as well?
- blauditore 6y ago
  The effect only occurs if the elements are small enough, so in fullscreen they are probably too large. You can step away from your screen a bit and you'll see the effect as well in fullscreen. As far as I understand, the effect is caused by the fact that the fovea has a much higher resolution (of bright light) due to its higher density of cones. At a certain size, the fovea is still able to make out details of the elements, but the rest of the retina can not. Thus they are detected as rotating in the fovea area, but not outside (since it's basically just a colored lump there. We still perceive the outside ones as stars (and not just color lumps) because the brain interpolates them that way due to previously perceived information. Under low light conditions, i.e. when rods would be the main means of vision, an opposite effect can be observed: We are mostly blind in the fovea area due to the lack of rods there. This manifests as objects showing more detail at night when looking slightly past them.
  - smcameron 6y ago
    The elements are the same size in windowed as in full screen though.
    - ebg13 6y ago
      It depends on the browser. In Safari they aren't.
aimor 6y ago
When I get close to the monitor the # of stars that appear to spin is greater than when I move my head far away. That is, the area of screen space with spinning stars increases as I get closer. Do other people get the same effect? I thought the opposite would happen.
- FartyMcFarter 6y ago
  I get the same effect. I think it makes sense, even though I understand your reasoning. Both the fovea and the rest of the eye perceive more detail when you're closer to an object (the fovea is no different in this respect). When you're close enough, the fovea can perceive a larger area in detail, which we see as motion in that animation.
- recursive 6y ago
  I get the same thing. I think it's because when you get close enough, you can see spinning even in the periphery, just because it's bigger.
deleted 6y ago
[deleted]
fudged71 6y ago
That's the size that is relevant to foveated rendering. But note that your actual physical fovea is even smaller than this, due to saccades.
- jessriedel 6y ago
  By what factor does it increase the apparent fovea size?
  - fudged71 6y ago
    I couldn't tell you a scientific answer. However, I have a vision condition where I can't see blue in my actual fovea. And that point is incredibly small. Maybe 3-4 times smaller than what you are seeing here.
    - vanattab 6y ago
      I was under the impression that everyone was blue blind in the fovea due to a lack of short wavelength cones in the fovea. This paper seems to confirm this but it is from 1967 and I am have trouble finding other references. https://www.osapublishing.org/josa/abstract.cfm?uri=josa-57-11-1289#:~:text=An%20area%20at%20the%20center,entirely%20lacking%20blue-sensitive%20cones https://www.osapublishing.org/josa/abstract.cfm?uri=josa-57-....
      - jessriedel 6y ago
        Note that this paper describes a lack of blue cones in only the very center of the fovea, corresponding to 7-8 angular minutes (or 0.03-0.04 mm). That's much smaller than the fovea as a whole, which is about 5 degrees or 1.5 mm. It's unclear whether fudged71 just has this normal condition, or actually has blue blindness over a wider region.
hwillis 6y ago
Note that if this isn't working, you are probably too close to your screen. I had to move back several inches to see any of the crosses as still.

Relevant: You can actually perceive the rough size of your fovea with this optical illusion: https://www.shadertoy.com/view/4dsXzM https://www.shadertoy.com/view/4dsXzM

TeMPOraL 6y ago

Very interesting. I was wondering what determines the speed at which the stars in foveal vision rotate. I assumed the movement is the illusion, but it turns out the stars all rotate - there's an explicit parameter determining their period in the shader. The illusion is that the stars outside your central vision seem frozen!

TemporalSux 6y ago
Your comment can be summed up as “I’m retarded”. It just consists of you completely wasting everyone’s time by articulating the slow journey of yourself comprehending what everyone else understood at a glance. How would your computer know where you’re looking you stupid fuck? Haven’t you posted enough comments by now? You have over 79000 karma points on this site. What the fuck? Give it a rest so other people can be heard you fucking windbag.

janekm 6y ago

Weirdly for me the "size of the fovea" is much smaller with the windowed view than fullscreen (seems to be the same proportion of the overall image), which doesn't seem to make sense. Perhaps another optical illusion is in effect as well?

blauditore 6y ago
The effect only occurs if the elements are small enough, so in fullscreen they are probably too large. You can step away from your screen a bit and you'll see the effect as well in fullscreen. As far as I understand, the effect is caused by the fact that the fovea has a much higher resolution (of bright light) due to its higher density of cones. At a certain size, the fovea is still able to make out details of the elements, but the rest of the retina can not. Thus they are detected as rotating in the fovea area, but not outside (since it's basically just a colored lump there. We still perceive the outside ones as stars (and not just color lumps) because the brain interpolates them that way due to previously perceived information. Under low light conditions, i.e. when rods would be the main means of vision, an opposite effect can be observed: We are mostly blind in the fovea area due to the lack of rods there. This manifests as objects showing more detail at night when looking slightly past them.
- smcameron 6y ago
  The elements are the same size in windowed as in full screen though.
  - ebg13 6y ago
    It depends on the browser. In Safari they aren't.

aimor 6y ago

When I get close to the monitor the # of stars that appear to spin is greater than when I move my head far away. That is, the area of screen space with spinning stars increases as I get closer. Do other people get the same effect? I thought the opposite would happen.

FartyMcFarter 6y ago
I get the same effect. I think it makes sense, even though I understand your reasoning. Both the fovea and the rest of the eye perceive more detail when you're closer to an object (the fovea is no different in this respect). When you're close enough, the fovea can perceive a larger area in detail, which we see as motion in that animation.
recursive 6y ago
I get the same thing. I think it's because when you get close enough, you can see spinning even in the periphery, just because it's bigger.

deleted 6y ago

[deleted]

fudged71 6y ago

That's the size that is relevant to foveated rendering. But note that your actual physical fovea is even smaller than this, due to saccades.

jessriedel 6y ago
By what factor does it increase the apparent fovea size?
- fudged71 6y ago
  I couldn't tell you a scientific answer. However, I have a vision condition where I can't see blue in my actual fovea. And that point is incredibly small. Maybe 3-4 times smaller than what you are seeing here.
  - vanattab 6y ago
    I was under the impression that everyone was blue blind in the fovea due to a lack of short wavelength cones in the fovea. This paper seems to confirm this but it is from 1967 and I am have trouble finding other references. https://www.osapublishing.org/josa/abstract.cfm?uri=josa-57-11-1289#:~:text=An%20area%20at%20the%20center,entirely%20lacking%20blue-sensitive%20cones https://www.osapublishing.org/josa/abstract.cfm?uri=josa-57-....
    - jessriedel 6y ago
      Note that this paper describes a lack of blue cones in only the very center of the fovea, corresponding to 7-8 angular minutes (or 0.03-0.04 mm). That's much smaller than the fovea as a whole, which is about 5 degrees or 1.5 mm. It's unclear whether fudged71 just has this normal condition, or actually has blue blindness over a wider region.

hwillis 6y ago

Note that if this isn't working, you are probably too close to your screen. I had to move back several inches to see any of the crosses as still.