Oculomotor and Monocular Cues

• Oculomotor Cues to Depth Perception:

  • depend on distance to object
  • Accommodation -

  *DISTANT VIEWING = Ciliary muscle relaxes = Zonules Stretch = Least Rounded Lens = Maximum Focal Length Reached

  *NEAR VIEWING = Ciliary muscle contracts = Zonules relax = Most Rounded Lens = Minimum Focal Length Reached

  • Vergence -

  *Vergence Angle = made b/w the eyes when they are fixated on object a given distance away

  *Difficult to recognise depth at distances > 10ft = smaller angle changes required for changes at greater distances

  *The closer the object, the larger the vergence angle
• 7 Monocular Cues to Depth Perception:

  • 7 cues (all used by artists except Motion Parallax)

  1)Linear Perspective - parallel lines appear to converge w/ increasing distance

  2) Occlusion - something blocking an object is closer to us than the object in question

  3) Texture Gradients - smaller, densely-packed  objects  that make up the texture appear farther away than those larger, less-densely packed
• 7 Monocular Cues to Depth Perception:

  4)Shadows and Shading - light comes from above, so the further away the object is from light source, the larger the shadow it casts

  *also biases our perception of convex/concave

  5)Relative Size - if we already know the real size of the object, we can judge how far they are as smaller objects appear more further away

  *Ames Room Illusion

  6)Aerial Perspective - further objects lose their coloration and become predominantly blue (due to greater scattering of light)

  7)Motion Parallax - further objects appear to be moving slower than nearer objects