This shader shows the extent of your fovea on your visual field:
https://www.shadertoy.com/view/4dsXzM

"Look at any specific point and you should clearly see the extent of your fovea (the stars only seem to be rotating in a small circle at the center of your vision). Move your head back and forth to see it grow/shrink. Works better in full screen mode."

(You need to click the link, not look at the static image.)

@timhutton Wow, that's cool!

And I also noticed: zooming the page in and out* changed my perception in *very* different ways than moving my head closer and further away.

* I'm using MacOS, where pinch-zooming is independent from website-scale-zooming and has a completely different effect. Not sure if/how the same can be achieved on other OSs. Also, neither of both zooming methods work in fullscreen mode.

@timhutton

Nice demo! It never ceases to amaze me how this fundamental fact of our biology has been so badly overlooked in modelling human vision.

https://mathstodon.xyz/@TonyVladusich/113305125309802195

Tony Vladusich (@[email protected])

Attached: 1 image Every single model of human vision is wrong. Not just a bit wrong, I mean just flat out wrong from the get go. The reason is that every single model incorrectly assumes that human vision is space invariant and passive, despite the obvious space variant nature of the retinal sensory array and the constant movements of the eyes to foveate targets. (Why these models incorporate false assumptions about the nature of vision continues to baffle me.) Yet, almost nobody knows about the incredible seminal work of the late Eric L Schwartz. (Eric was my friend and mentor in my years at Boston University.) If anybody deserved a Nobel prize for applying physics principles and techniques to neuroscience, it was him. Eric died in 2019, so he won't be winning any prizes, let alone Nobel prizes. (He'd be laughing in his grave at the fact that Hinton and Hopfield won the prize, and his long time colleague and "rival" Stephen Grossberg was snubbed.) Eric applied methods of complex analysis, vector calculus, and conformal mapping to create a rigorous framework for understanding the computational architecture and functional properties of the primate visual cortex. His work focused on space variant active vision and computational neuroscience (in fact, he coined both terms). Here is one of his great review papers on the computer vision applications of his work. https://www.sciencedirect.com/science/article/pii/0893608095000925

Mathstodon

@timhutton

ps, I have no fucking idea why this works btw! It is a very unique demo afaik.

I don't know what to do with this information!
@nigel Science! If it isn't a small circle, let us know. Some people might have a genetic difference or a medical condition that affects their fovea.

@timhutton

"If it isn't a small circle, let us know."

My typical computing is done over VNC, which didn't seem to provide the timing or resolution for the fovea shader to work. I finally got the hi-res version downloaded from YouTube to loop on my 12.9" iPad...

My vision is horrible, I have to get really close to the screen to see the tiny shapes rotate. Once they are clear enough, I'd say the angle of view that is rotating is around 20 degrees - more than the macula, and way more than the fovea, even when some sites say it is 5 degrees instead of 2 or 1 degree.

I'm sure my situation is rare and irrelevant, but I'm curious if there is some structural boundary in my eyes that creates this wide angle.

In daily life I'm quite aware that I depend on my dorsal stream and body movement for details of my world. Flat images are hard to resolve.

@timhutton That's so cool. I had to change the `scale` parameter to ~200, perhaps because I'm using a 4k display?
@timhutton at first I was disappointed, because I looked at the static image ^^
@timhutton I've never seen anything like this as a science demo before. It's very excellent. Thank you!

@timhutton nice, though i think it shows something a bit broader than the fovea

i still sometimes like to make much simpler static demos like this, high-frequency line gratings of different colors, you can get neat multi-tier effects - at the right distance, a red-green grating appears red-green centrally, but at larger eccentricities you see a yellow-black grating! (then at still larger eccentricity you just see yellow). as you foveate different positions, the inhomogeneous appearance follows.