Relative Size (Monocular Cue)

Relative Size is a monocular cue,a depth cue that is able to seen with one eye only, that the mind uses to infer the distance between yourself and two objects of the same size. If you know that two objects are the same size, the mind infers that the one that appears smaller in our field of vision is farther away, whereas, when an object appears larger, it is perceived as being closer. For example, the image below displays a mosque with two minarets that are of equal size. However, because one minaret appears smaller than the other, we can infer that it is farther away from the photographer than the one that appears larger.