Follow - up to 'Why do thing look smaller just because they are further away?'?

Question

Most of you seem to be saying 'because they do!'-but would anyone be happy with the answer 'because it is!' to the question 'why is the sky blue?'
Thks Larry M for seeing the real question beyond the obvious.
To expand it further-
Since it is true that objects stay the same size regardless of their distance, is it fair to say that 'objects only look smaller - the greater the distance-due to the way the human brain organizes information, in order to allow the viewer to make sense of the world around them?'-Indeed if there existed a species which used sound as a primary method of observation-that their brains might not sort information in this way-and who might 'see' objects at great distance at 'full' size-generating a confusing mass of image and perspective, making their visual senses less usefull than hearing or touch? and while I understand the concept that less light reaches the observer-the greater the distance-why doesn't it result in a dimmer image rather than a smaller one?

Answer 1

I believe it is due to the angles of the light as they hit your retina. (Think of tennis ball hitting the surface & reflecting). The pupil is a hole that allows light to pass through it. The closer an object is, the wider the angle and the further something is, the narrower the angle. Your brain then organizes the information from the nerve fibers that are "excited" on your retina to help you perceive the distance. It uses the input from both eyes (and the distance between them).

Also, in case this helps, you need both eyes to accurately perceive distance/spatial/3D movement and relations. That's why when people injure one of their eyes (or cover it for a while), their depth perception is all messed up...you may try to reach for a glass in front of you and completely miss.

Hope that helps.

Answer 2

I think the answer is that the from an early age, the human brain 'programmes' itself to understand size by measuring the angle at the eye which an object occupies.

As an object moves further away it's size obviously remains constant, but the angle between the top of the object and bottom of the object to the eye gets smaller. The brain interprets that as the object being smaller.

In maths terms: Tan (angle) = height of object / distance away
As you increase the distance away, the angle decreases.

Young babies develop the 'how far away is it' ability by reaching out to nearby objects and also work out 'how big is it' by touching near objects. In this way the brain develops a sense of 'yes it looks smaller, but that's because it is further away'. This ability of the brain is then further developed through to adulthood to the point where one can estimate size and distance by subconsciously working the comparisons between expected height and perceived height.
It works well, only being deliberately fooled by visual illusions. Think about crossing the road - you see an oncoming car in the distance. You assume it cannot change size, therefore the increasing angle it occupies in your eye means it must be getting closer, and your mind compares it's rate of change and perceived distance away to work out whether you have time to walk across the road. Clever thing the old brain!

Answer 3

If an object didn't change in some fashion relating to distance then how would we ever know what was near and what was far ?

This is an evolutionary necessity so that we can categorize dangers and take the necessary evasive action.

Something close needs immediate action, something farther away can be considered for a moment or two.

By the way there is a flaw in your original premise as you do not specify the relative velocities of the observer and observee.

Answer 4

==> THE OBJECT DOES NOT STAY THE SAME SIZE REGARDLESS OF THEIR DISTANCE.
You should go and learn how your eyes works, it is very difficult for me to explain it in words.

Imagine a dot and a line, Joining the dot to the two ends of the line make a triangle. If the line goes further away, the angle of the triangle (the angle where the dot is) is smaller and smaller.

The dot is the the front of your eye and the line is the object. However, you do not see objects at the front of your eye, you see them at the back of your eye where the nerves are. At the back, the object will be inverted but your brain inverts it back. If angle is very small (the object/the line is very far away), then the picture at the back of your eye will also be very small. If the angle is very big (the object/the line is very near), then the picture at the back of your eye will also be very big.

So the further the object, the smaller you see it.

Answer 5

As one person said, it is perspective. It is simple geometry, or maybe trigonometry. A tall blank wall seen up close covers half the sky, from your feet almost to the point straight up. If you drew a diagram, with a man standing next to a tall wall, then you could draw a triangle with one corner at the man, one at the top of the wall and one at the bottom of the wall. The triangle would be thin and tall and angle of the triangle's corner at the man would be nearly 90 degrees. We say the wall subtends an angle of 90 degrees. Now place the man at a distance from the wall equal to it's height and draw the triangle again. Now the angle at the man is only 45 degrees. He sees the wall covering only a quarter of the sky and sees the top 45 degrees up instead of 90. We say the wall subtends an angle of 45 degrees. The angle something subtends is the only information we have. We can't tell if the wall is 100 feet tall and 100 feet away or 1,000 feet tall and 1,000 feet away, but we can tell that it subtends half the angle from far away that it does close up. In other words, it looks smaller, A quarter of the sky in size instead of half the sky.

Answer 6

When many have tried their best to answer your question, you are appreciating an answer that satisfies your weird question.

For a weird question a weird answer will be correct.

It is not true that objects stay at the same size. How will you prove that they do have the same size with out nearing them?

They actually reduce in size as they go far away.

If we reach near them they grow in size.

On the other hand if we have an eye which can vary its size according to the object, then we will see the objects in their real size whatever their distance be.

Answer 7

right

but they "appear" smaller because they take up less space in our viewing range

we can cover the sun with our thumb. the sun is bigger than our thumb but not to our brain which sees it fully covered

however, the brain is so good, it will still interpret a mountain as bigger than your thumb even when it is so far away you can cover it with your thumb

and of course, the organisms that we know of that use sound for observation also have brains that can tell by the strength of the sound echo how far objects are away and can translate the signals into workable observations (that a species might exist with an inadequate brain for his is speculative)

Answer 8

It has absolutely nothing to do with the brain, just the design of our eyes.

The first type of vision is usually referred to as Linear perspective. Parallel lines seem to converge into a vanishing point.
The second type of vision wouldn't be very useful for survival, but is employed in many computer aided design programs. I am unfortunately unsure of what the term for that type of perspective so I can't help you research it any further.

Answer 9

Perspective

Answer 10

Incorrect, you do not need both eyes for depth perception/3D spatialisations or judgements thereof. Your brain can make the necessary adjustments well enough.

"I knows deez fings", said the object in the wing mirror.