Mirror, Mirror on the Wall. Who's the Farthest of them all?

This first picture on the right side gives us many pictorial cues that may indicate how far and how big the objects are in the picture. Look at the picnic tables, they are in front of the trees and partially hide their bases. This means that the trees are farther away from the tables. This cue is called the Occlusion.

Look at the picnic tables again. We know that they are all the same in size. Some tables are small in view, thus they take up less of the field of view, and others are much larger. This shows that smaller tables in view are farther away from the tables that are larger. This cue is called Relative Size.

Another cue we can see in this picture is the Atmospheric Perspective. If you look at the middle of the picture, we can see a blurry kind of scene. The objects in that area are less sharp and bluer. This means that these are farther away from the objects that are sharp and well defined.

Lastly, we can observe a cue called Texture gradient. Examine the fallen leaves on the ground. Some leaves are close together and some are not. This gives us a hint on the distance of those leaves. Those that are close together are farther away from those that are not. This is what the texture gradient cue states. The more closely packed the elements, the more the distance increases.

For this next picture, we can see the end of the bridge. The part of the bridge that is narrower in view is actually farther from the part that is wider in view. This cue is called the Perspective Convergence.

And that is how the environment gives us information about the distance of the objects inside it without using any measuring material and lots of brain works. Though it still uses some but we just look at the object and TADDDAAAAH! There it is!

Reference: