Final: Monocular Cues to Distance Flashcards
What is interposition? What is it also known as? What does this enable us to do? What is this related to?
AKA Occlusion
Closer objects partially block the view of more distant objects. Enables us to complete and recognize objects.
Related to perceptual phenomena such
as transparency and illusory contours
What is aerial perspective? Give example.
The visibility of distant objects can be compromised by an accumulation of pollutants or moisture in the air.
- With increasing depth (distance), objects lose contrast, both internally and with respect to the background.
- Stimuli having lower luminance contrast with respect to the background are perceived as ‘farther’.
Example: A painting of mountains in the background. They are usually slightly more foggy (lower contrast) which gives perception of them further away.
What is chromostereopsis?
Perception of depth depending on color.
Describe the monocular cue “height of field” both above and below the horizon. Give example.
Above the horizon, objects closer to the horizon are perceived as FARTHER away.
Below the horizon, objects closer to the horizon are perceived as FARTHER away.
Example: A painting of road, in distance the objects get closer to the horizon.
Describe the monocular cues to distance by “Shading and Shadows”
Perception of shape and depth can be affected by how a scene is illuminated.
When referring to shading and shadows, what determines whether the surface appears convex or concave?
The direction of light with respect to our retina. The direction of the light is implied by the shading.
Describe the monocular cues to distance by “Cast Shadows”
Changing location of shadows changes the perceived depth of objects
What is convergent projection?
Parallel lines extending off into the distance in real world, 3D space project as ________ lines on the retina.
Parallel lines extending off into the distance in real world, 3D space project as convergent lines on the retina.
Describe the monocular cues to distance by “Linear perspective”
Distance is indicated on a flat picture by CONVERGENCE (of lines) to the vanishing point.
What monocular cue of distance does the Ponzo illusion take advantage of?
Ponzo illusion is image of railroad tracks going off in distance with two lines. One line looks larger than the other but really, they are the same size
Linear perspective.
Describe the monocular cues to distance by “Relative velocity”
Given 2 objects moving across the visual field with the same linear velocity, the closer one, moving at a higher angular velocity, appears to move faster.
Describe the monocular cues to distance by “Motion Parallax”
While moving one’s self and fixating a point in space…
Direction of Motion:
objects more distant than the point of fixation will appear to move in the SAME direction as your head (“with” motion)
objects nearer than the point of fixation will appear to move in the OPPOSITE direction as your head. (“against” motion)
Velocity of Motion:
The point of fixation remains motionless (zero velocity)
Objects that are more distant from the point of fixation will appear to move faster. (May be closer to you than fixation or farther from you than fixation.)
The SIZE of an object’s image on the retinal provides _________ information regarding the object’s size and distance from the viewer.
What does this mean?
Ambiguous.
Means a small retinal image may equally represent a small, near object or a large, distant one.
In the absence of other cues, smaller objects are perceived as ___________ if the observer assumes the objects are the same size.
farther away
Describe the monocular cues to distance by “Looming”. Give example.
An object that gradually increases in size in all dimensions at the same rate is perceived as moving toward the observer.
If decreasing in size in the same manner, it is perceived to be increasing in distance from the observer.
Example: Blowing up a balloon
Describe Texture Perspective (size scaling)
Adding texture to image can help distinguish angle of object or distance.
Texture is _______ in a distant object than in a near object
more dense
The __________ of the image of a single texture element indicates inclination only if the true shape of the texture element is known.
aspect ratio
Describe perceptual constancies. Give example
There is a “top down” perception of objects that is unchanged despite changes in the sensory input.
Example: Viewing a coin at different angles. We assume the shape is still circular even though the angle we see it at might be oval.
Describe perceptual constancies. (color constancy). Give example.
Color constancy: The perceived color of objects remains relatively constant under varying illumination conditions.
Example: Knowing the color of each square of a rubic’s cube with different filters placed on the picture. The “red” square on the cube will appear different colors on both images but we know it is still red.
Describe perceptual constancies. (size constancy). Give example.
Size constancy: Known objects are perceived as having relatively constant size despite the fact that their retinal images may vary greatly in size.
_______ of size and position within an image provide a “structural invariant” (gradient) by which size constancy may be obtained.
Ratios
What is Emmert’s Law?
An object’s perceived size depends upon its perceived distance from the viewer.
What is SILO? What does it stand for? Give example.
For two objects to have the same retinal image size, the closer one must be smaller and the more distant one must be larger.
SILO- Small In Large out
Example: The BO prism test & “Over-minusing”. Making image smaller. Convergence signals proximity.
What is the moon illusion an example of? Describe how it happens. (moon looks larger at horizon)
Example of SILO.
The sky at the horizon is perceived to be farther away than is the sky directly overhead.
So, if we perceive the sky to be closer overhead, the moon would be perceived as smaller.
What is the Ames trapezoid room an example of?
Linear perspective/ size monocular cue
In the depth perception theory, what two monocular cues have a consistent ability to judge depth and distance no matter what distance you are viewing the object from?
Occlusion and Size constancy
In the depth perception theory chart, as the distance increases, what monocular cues have a decreasing depth contrast?
Convergence, Cast Shadows, Stereopsis, and Motion Parallax (starts out going up but goes down shortly after)
In the depth perception theory chart, as the distance increases, what monocular cue has a increasing depth contrast?
Aerial
