# Tag Info

## New answers tagged vision

1

This depends on the reflectivity of the objects and the size in the sky. The visual albedo of the moon when near (but not at) full, is about $0.12$. Earth's is around $0.39$. Being in low-earth orbit, the actual amount will vary based on the terrain and atmosphere. If it's overcast below, the value could be much higher. You can assume that a given area ...

1

This Q boils down to How bright is Earthshine? According to the usual source Oceans reflect the least amount of light, roughly 10%. Land reflects anywhere from 10–25% of the Sun's light, and clouds reflect around 50%. So the amount of sunlight reflected (i.e. albedo) depends on what part of the earth is facing your observer and how cloudy it is. ...

8

This isn't a physics phenomenon, but a biological one - look up persistence of vision. Basically our eyes have a limited response time so if we flash two different images quickly we will see an average of both images. TV uses this to appear to give us smooth motion where in reality it is flashing images every frame. If we assume we need a 25Hz frame rate ...

3

Because in the retina of human eyes there are light detector cells of two kinds: rods and cones. Cones "see" colors but are not very good with low brightness. Rods don't detect colors but are better than rods in low brightness situations. Thus at night cones don't function (they are for bright light) and we see only with rods which don't differentiate ...

-5

With my understanding, any color except black will reflect light, and a black color will absorb light without reflecting back out. So, at night, there won't be enough light to shine on anything to have a reflection. Then, your eyes won't see anything

1

red/blue double image is the (very) old technology to see 3D on paints, drawings and ordinary screens. See 'Anaglyph' on wikipedia. It requires red/blue glasses (very cheap on Ebay :-) ). Polarized display is expensive, and is the one requiring polarized glasses.

5

There are multiple clues to perceive 3D: static sterovision with at least 2 point of view (i.e. depth information obtained via parallax, or disparity). dynamic stereovision (like birds shaking their head: see examples in the third part here ) eye distance accomodation shape from shading, i.e. light reflection telling you clues about orientation of surfaces ...

1

Stereo vision is just one (though powerful) source of depth information. Eye focus and microsaccades still give one-eyed people some depth perception and combined with pure reasoning/inference from 'known' objects allows to approximate distance. A species with a single eye could be expected to augment those features for better depth perception from a ...

1

It's not really due to the fact that we have two eyes but that to detect parallax there needs to be a sufficient amount of separation between points in the visually receptive area. If we were, instead of human beings with two eyes, something similar to cyclops which had just one eye; then one might suppose that with a large enough eye - that is stretching ...

4

The question you are asking is something that engineers of Virtual Reality (VR) companies have had to ask themselves many a time, and there are weird effects, like a gender dependence, on how we perceive in 3D. There are actually a large number of factors that effect how we perceive colors. WetSavnnaAnimal already meantioned stereopsis, or 2 eyes effect ...

10

You can't understand depth as well with one eyed sight. But the "photogrammetry" (the process of inferring depth from images) done by our minds only partly depends on stereopsis (depth inference from images on taken at slightly different positions / in planes at slight angles). The mind subconsciously brings to bear all kinds of heuristics and rules it has ...

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