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Binocular Vision Outline

Binocular Vision Outline. Convergence of the eye as a cue to depth Binocular disparity as a cue to depth Limitations on stereopsis The computational problem of stereopsis. Binocular Convergence. Left retinal image. Right retinal image. Binocular Disparity. D = a - b. B. A. C. D.

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Binocular Vision Outline

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  1. Binocular Vision Outline • Convergence of the eye as a cue to depth • Binocular disparity as a cue to depth • Limitations on stereopsis • The computational problem of stereopsis

  2. Binocular Convergence

  3. Left retinal image Right retinal image

  4. Binocular Disparity D = a - b

  5. B. A. C. D.

  6. Horopter

  7. Positive disparities = Uncrossed disparities Negative disparities = Crossed disparities

  8. Stereo fusion • Objects are “fused” when brain interprets disparate images in the two eyes as being the same object and perceives the depth of the objects

  9. Stereo fusion • Objects are “fused” when brain interprets disparate images in the two eyes as being the same object and perceives the depth of the objects • When disparity gets too large • Double vision, • or brain ignores input from one eye

  10. Panum’s fusional area • Range of depth’s that can be “fused” Panum’s fusional area

  11. Size of Panum’s fusional area • Disparity limit = 10 - 60 minutes of arc

  12. Size of Panum’s fusional area • Foveal Disparity limit = 10 - 60 minutes • for fixation at arm’s length, depth range = five inches or so

  13. Size of Panum’s fusional area • Foveal Disparity limit = 10 - 60 minutes • for fixation at arm’s length, depth range = five inches or so • limit increases with size of object

  14. Size of Panum’s fusional area • Foveal Disparity limit = 10 - 60 minutes • for fixation at arm’s length, depth range = five inches or so • limit increases with size of object • limit is larger for slowly moving objects

  15. Size of Panum’s fusional area • Foveal Disparity limit = 10 - 60 minutes • for fixation at arm’s length, depth range = five inches or so • limit increases with size of object • limit is larger for slowly moving objects • Limit is larger in periphery than in fovea • As large as 3 degrees

  16. Arrangement of wires

  17. Arrangement of wires

  18. Virtual world

  19. Disparity acuity • Disparity acuity in fovea - as small as .05 minutes of arc.

  20. Disparity acuity • Disparity acuity in fovea - as small as .05 minutes of arc • depth resolution = .036 cm at arm’s length

  21. Disparity acuity • Disparity acuity in fovea - as small as .05 minutes of arc • depth resolution = .036 cm at arm’s length • Acuity is much better in fovea than in periphery

  22. Why fovea/periphery differences • Range of disparities in natural scenes. • Fovea - high depth acuity. • Periphery - provides coarse information about where to make convergence eye movements.

  23. Binocular Vision Outline • Convergence of the eye as a cue to depth • Binocular disparity as a cue to depth • Limitations on stereopsis • The computational problem of stereopsis

  24. Two Computational Problems of Stereopsis • How does brain compute depth from disparity? • How does it know what in the left image to match to what in the right image?

  25. Two Computational Problems of Stereopsis • How does brain compute depth from disparity? • How does it know what in the left image to match to what in the right image?

  26. D = a - b

  27. ∆Z Z D = a - b

  28. ∆Z D = ∆Z * I / Z2 Z I D = a - b

  29. ∆Z D = ∆Z * I / Z2 ∆Z = D * Z2 / I Z I D = a - b

  30. What happens to depth acuity as vergence depth increases? • What happens to the range of fusable depths (Panum’s fusional area) as the vergence depth increases?

  31. Two Computational Problems of Stereopsis • How does brain compute depth from disparity? • How does it know what in the left image to match to what in the right image?

  32. Midline of retinal image Right retinal image Left retinal image

  33. The Correspondence Problem - Many possible matches for each point

  34. The Correspondence Problem - Why not this interpretation?

  35. The Correspondence Problem - Why not this interpretation?

  36. The Correspondence Problem - Why not this interpretation?

  37. Solution • Constraints on objects in the world • objects are solid and opaque • objects are for the most part are smooth

  38. Solution • Impose constraints from the world • objects are solid • objects are for the most part are smooth • Matching constraints • Uniqueness • Ordering

  39. The Correspondence Problem - Why not this interpretation?

  40. Matching Constraints • Uniqueness • Ordering • Smoothness • Compatibility • If no compatible parts of two images are find, one gets binocular rivalry.

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