DEPTH PRINCIPLESThe ability to accurately estimate

the distance of objects and therefore perceive the world in

three dimensions

-Binocular depth cues (Requiring the use of both eyes)

=>Convergence=>Retinal Disparity.

-Monocular depth cues (Requiring the use of one eye only)

=>Accommodation=>Pictorial cues: Linear perspective,

interposition, texture gradient, relative size, height in the visual field

C: Convergence (Binocular)

A: Accommodation (Monocular)

R: Retinal Disparity (Binocular)

T: Texture Gradient (Monocular-Pictorial Cue)

H: Height in the visual field (Monocular-PC)

R: Relative Size (Monocular - PC)

I: Interposition (Monocular-PC)

L: Linear Perspective (Monocular-PC)

Binocular Depth Cues

Convergence Brain detects, then interprets tension

from eye muscles when the two eyes turn inwards (towards the nose) to focus on near objects

Convergence

Retinal Disparity Retinal disparity is a binocular

depth cue which comes about due to the fact that our eyes are set apart by 6-7 centimetres.

Consequently, each eye receives a slightly different retinal image due to each eyes slightly different angle of view. A combination of both eyes retinal image gives us information where we can judge distance

Monocular Depth Cues

Accommodation Accommodation is a depth cue involving

changes in the shape of the lens of the eye.

The lens bulges to focus on nearby objects and flattens to focus on objects which are far away

By bulging the lens becomes more convex and therefore refracts light more severely in order to reduce a large (close) image down to a size that can still be accommodated by the retina.

The lens flattens for more distant objects because it does not need to refract the light so much in order to fit the image onto the retina

V

LEARNING TIP:To remember the shape of the lens for different distances, Imagine its cross-section.

The shorter diameter is for shorter distances, whereas the longer, flatter lens is for long distances.

Pictorial Depth Cues

These monocular cues are so named because of their extensive application by artists in providing a three-dimensional perception of something that exists on a two-dimensional surface.

Linear Perspective, Texture Gradient, Height in the Visual Field, Relative Size, Interposition

Linear Perspective Linear perspective

is one of the most basic skills of artistry to create apparent depth.

Parallel lines are made to converge as they extend up the page to an imaginary vanishing point (where they theoretically come together) at the horizon.

Texture Gradient Progressive

change from coarse to fine texture of surfaces with distance provides depth (distance) information

Interposition Partial obscuring

(blocking) of one object by a closer object

Relative Size The larger of two objects (i.e. the one

that casts the larger retinal image) tends to be perceived as near (in the absence of other cues)

Height in the Visual Field

Objects below the horizon and moving higher in the visual field are perceived as being further away; objects above the horizon and moving lower in the visual fields are perceived as being further away.