The Explanation of How We See the Size of an Object

The size of an object while seeing it through eyes depends on the visual angle/ distance and not on the real size of the object. If the object is close to the eyes the visual angle will be higher and when it is far away the angle will be smaller. This is why the size differ. When we view two object we know to be the same size and now appears smaller than the other, we assume the smaller of the two is further away.

Gradient

The closer we are to an object, the more details we can see the surface texture. Objects with a smooth texture are usually interpreted as being further away. A way to consider the condition that the further away objects are, the smaller their visual angle, or the smaller their image on your retina is with a perspective illusion.

Binocular Vision

In biology, binocular vision is a type of vision in which an animal having two eyes is able to perceive a single three-dimensional image of its surroundings. Looking at a nearby object, eyes are bring together the muscle content associated with viewing a close objects provides information about the distance. The closer an object to the viewer, the more the eyes must turn in to register the image. The fact that we have two eyes (binocular vision) also provides information on distance. Convergence refers to the turning in of our eyes as objects come closer to our eyes. The other thing that happens as objects come closer is that our accommodation (the process by which the eye changes optical power to maintain a clear image or focus on an object as its distance varies) changes. There is a change of focus that occurs when the lens gets fatter for nearby objects.

Induced Motion

Induced motion is influenced by the frame of reference. Usually, the larger object appears stationary and the smaller object appears to move. An example of this is looking at the moon on a partially cloudy, windy night. It appears that the moon is moving through the clouds, although the opposite is the case. Related to this effect is the induced movement of your location caused by movement around you. Have you ever stopped at a red light and feel like you are moving backwards if the cars on both sides of you begin to inch up? You can also get this induced movement when watching 1st person roller coaster movies, or moving camerawork in those super wide field cinemas.

Human Eye Accommodation

Focus in the eye is controlled by a combination of elements including the iris, lens, cornea, and muscle tissue, which can alter the shape of the lens so the eye can focus on both nearby and distant objects. However, in some instances these muscles do not work properly or the eye is slightly altered in shape, and the focal point does not intersect with the retina (convergent vision). As people age, the lens becomes harder and cannot be properly focused, leading to poor vision. If the point of focus falls short of the retina, the condition is called nearsightedness or myopia, and people with this affliction cannot focus on distant objects. In cases where the focal point is behind the retina, people have trouble focusing on nearby objects, and have a condition called farsightedness or hypermetropia. These malfunctions of the eye can usually be corrected with eyeglasses using a concave lens to treat myopia and a convex lens to treat hypermetropia.

As things get further away, they take up less of our field of vision, making them appear smaller. Because we’re so used to this we make assumptions when looking at 2D images. For example, “train track”, with this train tracks illusion, we assume that as the lines get closer, they must be travelling off into the distance, so the line across them at the narrow end must be bigger as it’s “so far away”. However, both lines are exactly the same length. We’re really good at compensating for the small images our eyes receive from faraway objects. So we know that something we can only really see as small, is actually really big. This actually makes it hard to judge how small the image really is. Looking at the moon, look down at the ground and make a gap between your finger and thumb of how big you think the moon looks, now hold your arm outstretched and see how close you were. It may look smaller than you thought.

As a conclusion here is the phrase “the more you look, the less you see”. This phrase explains how we see things; It has to do with focus. The more you narrow your focus on something the narrower your view becomes and the less you see. And it also means the more you focus on the small visible details of an objects, the more you miss the big picture which contains the overall package of the object.