depth cues

what is depth perception?

depth perception is the ability to accurately estimate the distance of objects and therefore perceive the world in three dimensions.

we make these judgements automatically and rapidly so that we can navigate our world safely and efficiently.

what are depth cues?

depth cues are sources of information from the environment or from within our body that help us to perceive how far away objects are and therefore to perceive depth

what are binocular depth cues?

binocular depth cues require the use of both eyes working together in order to provide information to the brain about depth and distance. these cues are especially important in determining the distance of objects that are relatively close.

convergence and retinal disparity are two types of binocular depth cues.

what is convergence?

convergence involves the brain detecting and interpreting depth or distance from changes in tension in the eye muscles. this occur when the two eyes turn inwards to focus on objects that are close.

the brain interprets greater tension in the eye muscles as an object gets closer and less tension as an object gets further away.

why is convergence not needed beyond 6 meters?

beyond 6 meters, the lines of sight from our eyes to the object are virtually parallel and there is no need for our eyes to converge to keep the object in focus.

what is retinal disparity?

retinal disparity refers to the very slight difference in the location of the visual images on the retinas, due to their slightly different angles of view, which enables us to make judgments about the depth or distance of an object.

how does retinal disparity work?

when two different retinal images are combined in the brain, the images received from each eye are compared. any disparity or difference between the two images provides information about the depth of the object or its distance from the viewer.

what are monocular depth cues?

monocular depth cues require the use of only one eye to provide information to the brain about depth and distance.

can monocular depth cues use two eyes?

monocular depth cues can operate with two eyes, meaning we can still perform many daily activities even if we lose vision in one eye.

what are the two monocular depth cues?

1. accommodation
2. pictorial cues
   • linear perspective
   • interposition
   • texture gradient
   • relative size
   • height in the visual field

what is accommodation?

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

what are pictorial cues used for?

pictorial cues are used by artists to create depth and distance on two-dimensional surfaces such as paper and canvas

what is linear perspective?

linear perspective is the convergence of two parallel lines as they come together at a vanishing point in the distance.

this makes our brain interpret that objects closer to the vanishing point are further away.

what is interposition?

interposition is when one object overlaps another. the partially blocked object is perceived as further away from the object that obscures it.

what is texture gradient?

texture gradient refers to 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.

what is relative size?

relative size refers to 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. however, this only applies if the objects being perceived are about the same size in real life.

what is height in the visual field?

height in the visual field refers to the location of objects in our field of vision, whereby objects that are located closer to the horizon are perceived as being more distant than objects located further from the horizon