Monocular and Binocular cues
 Depth perception refers to our ability to judge
distances
 If we did not have depth perception what
problems would we have?
 How do we see the world in 3D when the
image displayed on our retina is 2D?
 Provide the information that lets us translate
2D information into 3D
 Depth cues are sources of information from
within our body (internal or primary depth
cues) or from the environment (external
secondary depth cues) that help us to
perceive how far away objects are and
therefore to perceive depth.
 Binocular – requires the use of both eye to
distinguish depth.
 Used for close objects and used greatly to
focus one these things
 Both binocular cues are primary internal cues
 Monocular – requires the use of only one eye
to perceive depth, but also operates with
both eyes
 Used for pictorial cues and over longer
distances
 Some monocular cues are primary some are
secondary
 Convergence
 Inward turning of the eyes to focus an image
on the retina
 The brain interprets greater tension in the eye
muscles as an object gets closer and less
tension as an object gets further away.
 Works within about 6m
 Retinal Disparity
 Our eyes are about 6-7 cm apart so each
retina receives a slightly different image.
 The difference in image decreases as the
object gets further away.
 Work for objects up to 10m away.
 Images are compared in the brain and any
difference give information about distance.
 Accomodation
 Accommodation involves the automatic
adjustment of the shape of the lens to focus an
object in response to changes in how far away
the object is.
 The flexibility of the lens enables it to bulge to fit
(‘accommodate’) close objects on the retina
• and to elongate (flatten) when looking at objects that
are further away.
 Pictorial Cues
 Artist use them to create depth and distance
on 2D sufaces.
 Linear Perspactive
 Interposition
 Texture Gradient
 Relative Size
 Height in the Visual field
 Linear Perspective
 the apparent convergence of parallel lines as
they recede (‘go back’) into the 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
 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.
 Relative Size
 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.
 objects being perceived must be expected to
be about the same size in real life.
 Height in Visual Field
 objects that are located closer to the
horizon are perceived as being more distant
than objects located further from the
horizon.
All the Pictorial Cues in one
picture of the Taj Mahal