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Stereopsis Prof. Fred Kingdom Department Ophthalmology

Stereopsis Prof. Fred Kingdom Department Ophthalmology. Reading Chapter in Adler ’ s on binocular vision Lecture PPT on http://www.mcgill.ca/mvr/resident/. Seeing Depth Part I Cues to depth Part II Stereopsis Part III Clinical tests for stereopsis. Part I. Cues to depth.

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Stereopsis Prof. Fred Kingdom Department Ophthalmology

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  1. Stereopsis Prof. Fred Kingdom Department Ophthalmology

  2. Reading Chapter in Adler’s on binocular vision Lecture PPT on http://www.mcgill.ca/mvr/resident/

  3. Seeing Depth Part ICues to depth Part IIStereopsis Part III Clinical tests for stereopsis

  4. Part I. Cues to depth

  5. Occlusion/Interposition Object size Position in field of view Cues to depth Texture gradients Linear perspective Shading

  6. Texture gradients/Perspective

  7. Atmospheric: Blueing with distance Occlusion/Interposition

  8. What is the perceptual hypothesis here?

  9. Depth from shading

  10. Depth from occlusion

  11. Depth from shadows

  12. Depth from shadows

  13. Depth from shadows

  14. Blur is important for depth perception

  15. Tilt-shift photography

  16. Kurt Wenner

  17. Part II.Stereopsis • Definition - Retinal disparity • - Horopters • - Stereoacuity - Stereoscopes and anaglyphs - Form-from-stereopsis - Correspondence problem - Autostereograms

  18. definition……….. Stereopsis is the means by which we determine the relative depth of objects by virtue of the fact that our two eyes view the world from a slightly different angle.

  19. Retinal disparity

  20. more definitions……. Retinal disparity is the difference in angle subtended by the image of an object between the two eyes, relative to fixation. Stereoacuity is the minimal detectable stereoscopic depth in units of disparity. Normal = 5-15 secs of arc; best is 2 secs. Fusion limit is the largest disparity that can be fused Diplopia is the experience of double vision

  21. Stereoacuity: Normal: 5-15 arc secs of arc; best is 2 secs. Fusion Limit (Panum’s limit): 1.5 - 20 arc mins Development: Abrupt onset of stereopsis at 3-5 months

  22. Horopters

  23. Wheatstone stereoscope

  24. Principle of anaglyphs

  25. Effect of disparity

  26. Random-dot stereogram Figural stereogram

  27. Random-dot Stereogram ‘global’ stereopsis Figural Stereogram ‘local’ stereopsis

  28. Random-dot-stereogram ‘Global’ stereopsis Figural stereogram ‘Local’ stereopsis

  29. ‘False-target’ or stereo-correspondence problem

  30. Autostereogram

  31. Autostereogram

  32. Clinical aspects Development: Abrupt onset of stereopsis at 3-5 months Critical periods: Infancy 6-10 months Childhood 10 months – 9 years

  33. Clinical aspects Stereoanomaly: Persons with a selective deficit in either crossed or uncrossed disparities (Richards, 1971), apparently unlinked to amblyopia Amblyopia: Strabismus and Anisometropia

  34. Tests for binocular vision and stereopsis Worth 4 dot: Test for binocular function Stereo Fly test: Test for ‘local’ stereopsis Stereo Butterfly: Test for ‘global’ stereopsis TNO: Test for ‘global’ stereopsis Randot E: Test for ‘global’ stereopsis

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