The eye – curved cornea – lens – retina – fovea – optic disk Using Light

photoreceptors transduce incoming light ganglion cells send signals along to the brain The Retina has layers of cells

2 types of photoreceptors: rods and cones rods are very sensitive - useful in dim light Two kinds of Photoreceptors

Rods and cones are distributed differently across the retina The Retina

visual acuity (ability to see detail) depends on cones - thus acuity varies across the visual field The Retina

Why don’t you notice your blind spot? The Retina

Why don’t you notice your blind spot? – Blindspots don’t overlap! – Your brain “fills in” the missing information – The specific information in the blindspot isn’t much more missing than the rest of the periphery! The Retina

three types of cones: short, medium, and long different absorptions enable color vision The Retina

Ganglion cells project to the brain via the optic nerve information is projected to contralateral cortex! Visual Pathways

Seeing Depth What’s the big problem with seeing depth ?

Seeing Depth The world is 3D, the retina is 2D !

Depth Cues Four categories: 1. Pictorial 2. Physiological 3. Motion 4. Stereoscopic

Depth Cues  Pictorial Depth Cues: aspects of 2D images that imply depth

Depth Cues  Pictorial Depth Cues: aspects of 2D images that imply depth  Physiological Depth Cues: Proprioception in ocular muscles indicates accommodation and convergence

Depth Cues  Pictorial Depth Cues: aspects of 2D images that imply depth  Physiological Depth Cues: Proprioception in ocular muscles indicates accommodation and convergence  Motion Depth Cues: foreground and background move in opposite directions

Depth Cues  Pictorial Depth Cues: aspects of 2D images that imply depth  Physiological Depth Cues: Proprioception in ocular muscles indicates accommodation and convergence  Motion Depth Cues: foreground and background move in opposite directions  Stereoscopic Depth Cues: disparity between two retinal images indicates distance

Pictorial Depth Cues – Occlusion

Pictorial Depth Cues – Occlusion

Pictorial Depth Cues – Shadows and Shading

Pictorial Depth Cues – Shadows and Shading

Pictorial Depth Cues – Shadows and Shading: visual system assumes light from above

Pictorial Depth Cues – Shadows and Shading: visual system assumes light from above

Pictorial Depth Cues – Shadows and Shading