Depth Cues

Introduction

 

Think of your favourite picture.  You know that when you look at it, you are looking at a flat, two dimensional representation of a three dimensional event.  Nevertheless, even if looking at that picture for the first time, you know that certain objects or people are closer than others.  How can something that is two dimensional project an image that is perceived in three?

 

When looking at an image, be it a two dimensional representation or three dimensional 'real-world' event, there are certain cues in the image that the brain picks up on.  These 'depth cues' give the brain clues about the orientation of objects in the image being perceived, and permits an accurate perception of the image to be interpreted.

 

There are many, many cues that the brain is able to pick up on in order to make an accurate perception.  These cues are generally divided up into four categories, based on certain characteristics.  

 

Monocular Cues involve those cues that exist for a single eye.  This is one of the major categories for depth perception, as there are several different monocular cues that help in depth perception.  Click the above link for more on monocular cues for depth.

Another important monocular cue for depth is provided by motion.  As the world moves, whether that movement is caused by the perceiver or by his surrounding environment, objects in the environment move in distinct, predictable patterns.  This concept is known as the motion parallax.  To learn more, click the above link.

Cues that involve both eyes are called binocular cues, and form the other major category for depth cues.  These cues exist because of the differential location of the two eyes.  The above link explains this phenomenon in more detail.

Proprioceptive information is also used by the brain as a cue for depth.  Oculomotor feedback from the muscles of the eye provides information that the brain can interpret as a depth cue.  To learn more about these cues, click the above link.

 

If you are interested in learning more about these cues for depth than is covered in these pages, there are a number of fascinating and informative web pages out there.  Links to these pages are provided here.  

 

Page design by Jen LaPierre, Jen Lee, Steph Egilo, and Darren Van Dam