370: Perceiving Depth and Size: Monocular Cues

1. One Eye vs Two Eyes
1. We know some basic reasons why two eyes help the brain assume a 3D world but what if you only have one eye?
1. You do lose some depth perception but not all of it
2. Oculomotor Cues
1. Oculomotor: cues based on sensing the position of the eyes and muscle tension.  As you converge/diverge your eyes it indicates things are getting closer/further away.
1. Accommodation: change in the shape of the lens when we focus on objects at different distances
2. One can't diverge beyond parallel vision
2. Lens
1. Things that are closer the lens will be thicker
2. Things further away the lens will be thinner
3. Monocular Cues
1. Monocular: cues that come from one eye
2. Pictorial cues: sources of depth information that come from static 2D images
1. Familiar size: this is a weak cue
2. Atmospheric perspective: things get bluish as they get further away
3. Texture grading: things closer have more detail and texture
4. Shadows: can reveal height but necessarily distance from us
5. Occlusion: occluded objects are further away
6. Relative height: closer to the horizon = further away
7. Relative size:
8. Perspective convergence: parellel lines tend to converge in the distance
3. Motion Cues: sources of depth info requiring...
1. Objects closer than fixation point "move backward" relative to moving observer
2. Objects further away will "move along" with the moving observer
3. Motion Parallax
1. one eye, moving from left to right, fixated at infinity showing how the images of a nearby tree and a faraway house move, the image of the tree will move more than the image of the house.