Monocular depth cues
What is it?
Depth perception allows us to perceive the world around us in three dimensions and to gauge the distance of objects from ourselves and from other objects. You can contrast monocular cues with binocular cues, which are those that require the use of both eyes.
Common monocular cues that we use to help perceive depth.
Overlap (or Interposition)
Aerial Perspective
Linear Perspective
Texture Gradient
Motion Parallax
Relative Size
Object that appear farther way from another object are higher on you plane view
The use of texture to gauge depth and distance, when you're looking at an object that extends into the distance, the texture becomes less and less apparent the farther it goes into the distance.
The perception of moving objects can also serve as a monocular cue for depth. As you're moving, objects that are closer seem to zoom by faster than do objects in the distance.
Objects that are farther away seem to be blurred or slightly hazy due to the atmosphere.
Parallel lines appear to meet as they travel into the distance. (ej: road)
When one object overlaps another, the object that is partially obscured is perceived as being farther away.
Shading and lightining
Objects that are darkened and obscured may appear further off in the distance than those that are brightly lit. (amount of shading and light)
Accomodation
When you focus on close-up objects, eye muscles contract, altering the shape of your lens. When looking at far away objects, these same muscles relax.
How they are used
When perceiving the world around us, many of these monocular cues work together to contribute to our experience of depth.
The corner of a building looks larger and more textured, causing it to seem closer. Objects further down the street appear smaller, so we judge them as being farther away. The parallel lines of the highway appear progressively closer as they disappear in the distance, and the mountains in the distance seem fuzzy and indistinct.