Topic 8- Perceiving depth and size Flashcards
Will describe the many ways we use…
…determine the depth and size of things in our environment.
different sources of visual and environmental information to help us
How do we perceive distances in the 3D environment?
Our ability to perceive these distances in the 3D environment is based entirely on the image (2D) that is hitting the retina.
What are the 3 major cues that signal depth?
- Oculomotor cues
- Monocular cues
- Binocular cues
What are oculomotor cues?
4pts
- Cues that rely on our ability to sense the position of our eyes and the feeling of tension in our eyes muscles
Created by:
1. Accommodation: Change in the shape of the lens that occurs when we focus on objects at various distances
- Convergence: Inward eye movements that occurs when we look at nearby objects
Together, these indicate when an object is close.
What are Monocular cues?
3pts
- Cues for depth perception that can work when we use only 1 eye
- Does include accommodation but mainly pictorial and movement-based cues
- Pictorial cues: Sources of depth information that could be gathered from a picture, without the need for movement
Pictorial monocular cues- What is the depth cue occlusion?
Depth cue in which one object hides or partially hides another object from view, causing the hidden object to be perceived as farther away.
Pictorial monocular cues- What is relative height?
Objects that are higher in the visual field are (usually) further away than objects lower in the visual field.
Pictorial monocular cue- What is familiar size?
Judgement of a distance based on previous knowledge of the size of objects.
Pictorial monocular cue- What is relative size?
When two objects are of equal size, the one that is farther away will take up less of your field of view.
Pictorial monocular cue- What is perspective convergence?
Perception that parallel lines converge as depth increases
Pictorial monocular cue- What is texture gradients?
Objects appear more textured when closer to us and less textured as distance increases
What pictorial monocular cue is this?
- Help us better determine the location and placement of objects relative to others
- Help with defining shape
Shadows
Movement Monocular cue- Motion parallax
As we move, nearby objects appear to be moving faster across our visual field, whereas farther objects appear to be move more slowly
Movement Monocular cue- Deletion and accretion
Moving sideways, some things become covered, and some things become uncovered (when it re-emerges)
What are binocular cues?
2pts
- Stereoscopic vision/stereopsis
- “Two-eyed depth perception” that considers differences in the images hitting the left and right retinal surfaces
What is binocular disparity?
Occurs when the 2 retinal images are slightly different angles, then the brain compares these 2 images and uses the difference/disparity to figure out the distance of the object
In binocular disparity what are the corresponding retinal points and the non-corresponding retinal points ?
2pts
Corresponding retinal points: points on the retina that would overlap if the eyes were superimposed on top of each other
Non-corresponding retinal points: points on the retina that would not overlap if superimposed
Objects that fall on corresponding points are located on the BLANK
If the angle is large= object is…
If the angle is small= object is…
horopter
- object is closer than the horopter/to us
- object is farther than the horopter/to us
