Depth cues

• Depth perception is the ability to accurately estimate the distance of objects and therefore

  perceive the world in three dimensions.
• Depth cues are sources of information from the environment (external cues) or from within our body (internal cues) that help us to perceive how far away objects are and therefore to perceive depth.
• Binocular depth cues require the use of both eyes working together in order to provide information to the brain about depth and distance.
• Convergence:

  When we look at things up close, our eyes turn inwards and

  our eye muscles are strained. This turning inwards is called
• Retinal disparity refers to the very slight difference (‘disparity’) in the

  location of the visual images on the retinas (due to their slightly different angles of view), which enables us to make judgments about the depth or distance of an object.
• Monocular depth cues require the use of only one eye to provide information to the brain about depth and distance, but they also operate with both eyes.
• Accommodation involves our lens bulging and flattening

  according to how far away an object is. In this way, our

  eye is accommodating for distance.
• Motion parallax uses our perception of movement to help us gauge how far away things are.
• Pictorial cues are so named because artists use them to create depth and distance on two-dimensional surfaces such as paper and canvas.
• Pictorial cues include:

  Relative size

  Height in a visual field

  Linear perspective

  Interposition (also known as overlap)

  Texture gradient
• Relative size refers to the tendency to visually perceive the

  object that produces the largest image on the retina as being

  closer, and the object that produces the smallest image on

  the retina as being further away.
• Height in the visual field refers to the location of objects in our field of vision, whereby objects that are located closer to the horizon are perceived as being more distant than objects located further from the

  horizon.
• Linear perspective is the apparent convergence (come together) of parallel lines as they recede (‘go back’) into the distance. In this way, our perspective of lines (linear perspective) allows us to gauge distance
• Interposition occurs when one object partially blocks or covers another, and the partially blocked object is perceived as further away than the object that obscures it (and vice versa).
• Texture gradient refers to the gradual reduction of detail that occurs in a surface as it recedes into the distance, compared with a surface that is close and perceived in fine detail.