SAP - Depth Perception Lesson

Depth Perception

Image showing Retinal disparityDepth perception is our ability to see objects in three dimensions. Remember that when an image strikes the retina it is two-dimensional. Depth perception is an important survival skill that enables us to judge distance. Therefore, we can avoid falling off a cliff, getting hit by a car, or bumping into others. In a famous experiment conducted by researchers Elanor Gibson and Richard Walk called the "virtual cliff" it was determined that infants develop depth perception sometime after they begin crawling. We can understand how we perceive depth by studying monocular and binocular cues.

Binocular Cues

Binocular cues allow us to see depth by using both eyes. There are two binocular cues you should know.

  • Retinal Disparity - Retinal or binocular disparity states that because we have two eyes our brain receives two images. Because our eyes are a couple of inches apart there is a slight difference in the images that are cast on the retina of each eye. When the two images are quite different, we see them as being remarkably close to us. When the images are identical, we see them as further away.
  • Convergence - Convergence states that as an object gets closer to us, we must strain our eyes to stay focused on the object. So the greater the muscle strain the closer the object is to us.

Monocular Cues

Monocular cues are depth cues that depend on one eye. Artists often use them to create depth perception on two-dimensional images.

The following are important monocular cues:

  • Interposition - if there is overlap or one image blocks another it is perceived as closer.
  • Relative Size - if we know that two images are around the same size the one that is smaller is perceived as further away.
  • Texture Gradient - as texture extends into the background it becomes hazy or less clearly defined.
  • Relative Height - objects that are higher in our visual field are perceived as further away.
  • Relative Motion or Motion Parallax - objects that are closer appear to move more quickly.
  • Linear Perspective - Parallel lines converge with distance into a vanishing point.

Please take a moment to view this video on Visual Cues.

Take a moment to complete the activity below.

Module Review

Complete the Sensation and Perception review activity below.

 

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