Depth PrinciplesMonocular and Binocular cues

Depth perception priciplesDepth perception refers to our ability

to judge distancesIf 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?

Depth CuesProvide the information that lets us

translate 2D information into 3DDepth 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.

Two types of depth cuesBinocular – requires the use of both

eye to distinguish depth.Used for close objects and used greatly

to focus one these thingsBoth binocular cues are primary internal

cuesMonocular – requires the use of only

one eye to perceive depth, but also operates with both eyesUsed for pictorial cues and over longer

distancesSome monocular cues are primary some

are secondary

Binocular Depth CuesConvergence

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

Binocular Depth CuesRetinal 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.

Monocular Depth CuesAccomodation

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.

Monocular Depth CuesPictorial Cues

Artist use them to create depth and distance on 2D sufaces.Linear Perspactive

Interposition

Texture Gradient

Relative Size

Height in the Visual field

Pictorial CuesLinear Perspective

the apparent convergence of parallel lines as they recede (‘go back’) into the distance.

Pictorial CuesInterposition

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).

Pictorial CuesTexture gradient

the gradual reduction of detail that occurs in a surface as it recedes into the distance, comparedwith a surface that is close and perceived in fine detail.

Pictorial CuesRelative 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.

Pictorial CuesHeight 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