/sci/ - Science & Math

>>12514205
depth perception

>>12514208
Well yeah, but I don't understand how that works though. Like is everybody's the same? Or is distance just something we agreed on, could two people actually be different distances from something but we tricked our brains into just agreeing an inch was an inch?

>>12514205
Predictive processing

>>12514205
perspective and atmospheric perspective
which is why faraway mountain on the moon appears closer

>>12515252
Also the moon is fake.

>>12514205
Your brain has two different ways of doing this. The first one is by knowing objects get smaller with distance. This happens automatically; you don't have to think about it. This is what you're using with photographs.

Your two eyes also produce two different images because they're not in the same place. Your brain combines these into one image with depth information. Hold something near your face and alternate which eye is open and you'll see it move left and right in your vision. This effect becomes less the further away an object is.

>>12514205
You look at something with two eyes, your brain triangulates automatically working out the distance.

>>12515263
you're fake

>>12514215
>>12514953
>>12515252
No. The distance can be calculated from the two images, exactly without guesswork. (though ambiguities can sometimes occur) What is far looks identical in both eyes, what is near looks shifted to the right in the left eye. This way, a 3D (or image + z for the not akshullee 3D shithead) image can be calculated.

>>12515263
ok, fuck the moon but remove those 2 effects and you'll still get the same result
>>12515643
did you know parallax effect gets weaker with distance?

maybe it works if somebody lived in such environment throughout their lives but normal earthling use all kinds of cues in addition to parallax for judgement.

>>12514205
Stereoscopic vision.
After that the brain fills in the details.

>>12515659
>did you know parallax effect gets weaker with distance?
Of course it does, that's the fucking way it works you fucking smartass idiot.

>>12514208
That's not it. You are still able to gauge distances even when looking at a photo.

>>12515711
your dumbass if you think people rely on parallax alone to judge distance

that said parallax works best for nearby object, unless your eyes 1 km apart

>>12514205
Now do it with one eye.

Good luck.

Your brain does parallax on the fly, you don't even have to consciously think about it.

That is an evolutionary advantage of compartmentalized brains.

The computation required to perform depth perception is probably significant, thus if you had to use your forebrain for it, consciously, your reaction times would be abysmal, even if you were more precise.

If you're trying to throw a spear into a mastodon at 80 meters, you need fast timing, in case it moves.

Snipers are humans that utilize our natural ability to perform parallax, but then also consciously use part of their forebrain as well.

They have become the best of both worlds, giving them an advantage over any average idiot that picks up a gun.

>>12516131
The parallax doesn't have to be enormous for it to work, the depth can be resolved as long as the difference can be. It fact it's possibly easier to do when it is tiny.
Close one eye, I don't know how you, but I lose depth perception pretty much completely when I do. I know that some things are near some are far, but I cannot see it.

>>12514205
>lust inducing image
>irrelevant, time-consuming question

>>12516480
>The parallax doesn't have to be enormous for it to work
wtf those dumbass planetary scientists has been doing it wrong

>>12514205
Lotta people in this thread ignoring focal length. You can judge distance with one eye.

>>12516480
To add, human eye is no precision instrument. parallax have to work just good enough for out ancestors to chuck spears at something 20m away not 10km. It is but a part of our visual sensory suite, we rely on all available cues to make sense of the world.

>Close one eye, I don't know how you, but I lose depth perception pretty much completely when I do.
Try this on a mountain or a ship or something further away and see if you could tell the angular difference. At that point you're relying on combination of some other cues to guess the plausible distance.

http://www.hitl.washington.edu/projects/knowledge_base/virtual-worlds/EVE/III.A.1.c.DepthCues.html
https://www.sciencefocus.com/the-human-body/how-small-can-the-naked-eye-see/

>>12516682
still only works at close range, the difference is extremely minute at distance

>>12516763
>At absolute best, humans can resolve two lines about 0.01 degrees apart
Assuming that is true: how far an object has to be to have parallax less than 0.01°?

>>12517090
Note this is probably very generous, since you only cannot tell two lines apart, you can still tell if two lines are shifted by less than that.

>>12516763
6cm×tan(98.998)=171887cm = ~1.7km
Which means you should be able to tell 1.7km, or a mile, from infinity, assuming rather mediocre Vernier acuity of 0.002 degrees.

>>12516763
>the human eye is no precision instrument
maybe yours isn't

>>12514205
Not this again... but it works of course.

>>12517215
you can tell exact angular size or albedo with 0 reference?
call the fucking guniess book.

>>12519195
There jyst isn't any other good reason why we determine the posotion of lines with such ridiculous precision than to allow good parallax processing.