DISTANCE ESTIMATION AND DEPTH PERCEPTION

Question 1

What are the two types of cues we use for distance estimation?

Answer 1

Binocular Cues and Monocular Cues

Question 2

What are binocular cues?

Answer 2

Depend on the slightly different view each eye has of an object. Binocular perception is of value only when the object is close enough to make a perceptible difference in the viewing angle of both eyes. Thus, binocular cues are of little value, as most of what we focus on is far beyond the scope of usefulness of binocular cues.

Question 3

What is a monocular cue?

Answer 3

Factors that aid in distance estimation and depth perception.

Question 4

What are the monocular cues?

GRAM

Answer 4

Geometric Perspective

Retinal Image Size

Aerial Perspective

Motion Parallax

Question 5

What is Geometric Perspective and what cues fall within Geometric Perspective?

Answer 5

An object may appear to have a different shape when viewed at varying distances and from different angles.

LAV

Linear Perspective

Apparent Foreshortening

Vertical Position in the Field

Question 6

Explain Linear Perspective.

Answer 6

Parallel lines, such as railroad tracks, appear to converge as distance from the observer increases.

Question 7

Explain Apparent Foreshortening.

Answer 7

The true shape of an object or terrain feature appears elliptical (oval and narrowed appearance) when viewed from a distance.

Question 8

Explain Vertical Position in the Field.

Answer 8

Objects or terrain features farther away from the observer appear higher on the horizon than those closer to the observer.

Question 9

What is Retinal Image Size and what cues fall within Retinal Image Size?

Answer 9

An image focused on the retina is perceived by the brain to be of a given size.

KITO

Known Size of Objects

Increasing/Decreasing Size of Objects

Terrestrial Association

Overlapping Contours

Question 10

Explain Known Size of Objects.

Answer 10

Familiarity with an object or classification of objects allows us to determine the relative distance to that object. The nearer an object is to the observer, the larger its retinal image.

Question 11

Explain Increasing/Decreasing Size of Objects.

Answer 11

If size is increasing, object is coming closer - if size is decreasing the object is moving farther away - if size is constant, object is staying the same distance.

Question 12

Explain Terrestrial Association.

Answer 12

Objects normally associated together (helicopter and heliport / airport) are judged to be at about the same distance and assist in determine size.

Question 13

Explain Overlapping Contours.

Answer 13

When objects overlap, the overlapped object is farther away.

Question 14

What is Aerial Perspective and what cues fall into Aerial Perspective?

Answer 14

The clarity of an object and the shadow cast by it are perceived by the brain and are cues for estimating distance.

FLP

Fading of Colors and Shades

Loss of Detail or Texture

Position of Light Source and Direction of Shadows

Question 15

Explain Fading of Colors and Shades.

Answer 15

Objects viewed through haze, fog or smoke are seen less distinctly and appear to be at a greater distance than they actually are. If light is unrestricted - the opposite is true because you can see the object more distinctly / more details - so it appears closer.

Question 16

Explain Loss of Detail or Texture.

Answer 16

As a person gets farther from an object, discrete details become less apparent (a corn field from high altitude looks like a green blob and everything seems to blur together - but up close, you can tell it is clearly a corn field with distinct rows and patterns).

Question 17

Explain Position of Light Source and Direction of Shadows.

Answer 17

Every object casts a shadow from a light source. The direction in which the shadow is cast depends on the position of the light source. If the shadow of an object is towards the observer, the object is closer than the light source is to the observer.

Question 18

Describe Motion Parallax.

Answer 18

(Most Important for depth perception) - Apparent relative motion of stationary objects as viewed by an observer who is moving across the landscape Near objects appear to move against the direction of travel Far objects appear to move with the direction of travel slightly, or stay stationary.