Depth perception cues
Depth perception cues give distance. Two types:
| Type | Needs | In flight |
|---|---|---|
| Monocular | One eye | Relied on |
| Binocular | Both eyes compared | Little value: most outside distances too great for usable difference in eyes' viewing angle |
- Binocular cues work more subconsciously and automatically than monocular.
Four monocular cues (geometric perspective = three related cues):
| Cue | Effect |
|---|---|
| Motion parallax | Looking perpendicular to flight path: near objects appear to move backward; far objects move with you or stay fixed. Apparent rate depends on distance |
| Retinal image size | Known object's image shrinks with distance; apparent size gives range (PHAK ch.17) |
| Geometric perspective: linear perspective | Parallel lines (runway lights, power lines, railroad tracks) converge with distance |
| Geometric perspective: apparent foreshortening | True shape of object or terrain feature looks elliptical when distant |
| Geometric perspective: vertical position in field | Farther objects sit higher on the horizon than closer ones |
| Aerial perspective | Colour, shade, detail, texture blur with distance. Shadow cast toward observer: object closer to observer than light source is |
Trap: binocular (both-eyes) distance judging in flight; works close-up only, distant objects need a monocular cue.
References
- PHAK ch.17, Distance Estimation and Depth Perception