Monocular Cues/Types Of Vision Flashcards
BINOCULAR CUES
binocular perception is of value only when the object is close enough to make a perceptible difference in the viewing angle of both eyes. However, since most distances outside the cockpit are so great, binocular cues are of little to no value to crewmembers.
MONOCULAR CUES
Cues assisting with depth perception
These cues are:
geometric perspective, retinal image size, aerial perspective, and motion parallax
GRAM
GEOMETRIC PERSPECTIVE
An object appears to have a different shape when it is viewed at varying distances and from different angles.
Linear perspective
Apparent foreshortening
Vertical position in field
Linear Perspective
Parallel lines such as railroad tracks tend to converge as distance from the observer increases
Apparent Foreshortening
The shape of an object or terrain feature appears elliptical (oval and narrow) when viewed from a distance at both higher and lower altitudes. As the distance to the object or terrain feature decreases, the apparent perspective changes to its true shape or form. When flying at lower altitudes and at greater distances, crewmembers might not see objects clearly
RETINAL IMAGE SIZE
Retinal image size is used in distance estimation. An image focused on the retina is perceived by the brain to be of a given size
Known size
Increasing/decreasing size
Terrestrial association
Overlapping contours
AERIAL PERSPECTIVE
An object’s clarity and its shadow are perceived by the brain and cues for estimating distance.
Fading colors
Loss of details
Position of light source
MOTION PARALLAX
Motion parallax is often considered the most important depth perception cue. Motion parallax refers to the apparent relative motion of stationary objects as viewed by an observer moving across the landscape. Near objects appear to move past or opposite the path of motion; far objects appear to move in the direction of motion or remain fixed
Monocular Cues
Geometric perspective
Retinal image size
Aerial perspective
Motion parallax
Geometric perspective
Linear perspective
Apparent foreshortening
Vertical position in the field
Retinal image size
Known size
Increasing/decreasing size
Terrestrial association
Overlapping contours
Aerial perspective
Fading colors
Loss of detail
Position of light source and direction of shadows
Motion parallax
As you get lower it seems faster
Day Blind Spot
Each eye compensates for the day blind spot in the optic disk of the opposite eye.
The day blind spot covers an area of 5.5 to 7.5 degrees and is located about 15 degrees from the fovea, originating where the optic nerve attaches to the retina.
Rod
responsible for night vision, which provides silhouette recognition of objects.
It is also why crewmembers’ eyes are highly sensitive to light during low ambient light or dark conditions.
Cone
Cone cells provide sharp visual acuity and color perception.
PHOTOPIC VISION
- Occurs in daylight or bright light
- Produces sharp images and color vision
- Requires use of central vision
- Involves cones only
MESOPIC VISION
- Occurs on dimly lit nights
- Decreases visual acuity
- Causes loss of color perception
- Causes night blind spot
- Requires use of peripheral vision and recognition of object silhouettes
- Involves rods only
SCOTOPIC VISION
- Occurs on dimly lit nights
- Decreases visual acuity
- Causes loss of color perception
- Causes night blind spot
- Requires use of peripheral vision and recognition of object silhouettes
- Involves rods only
Dark adaptation
for optimal night vision acuity approaches its maximum level in about 30 to 45 minutes under minimal lighting conditions
Vertical Position in the Field
Objects or terrain features at greater distances from the observer appear higher on the horizon than those closer to the observer
Known Size of Objects
The nearer an object is to the observer, the larger its retinal image.
Increasing or Decreasing Size of Objects
If the retinal image of an object increases in size, the object is moving closer to the observer
Terrestrial Association
Comparison of one object such as an airfield with another object of known size such as a helicopter helps in determining the relative size and apparent distance of the object from the observer.
