1. Stereograms seeing depth requires “only” two different images on the retina

2. Stereograms seeing depth requires “only” two different images on the retina this could be accomplished by an optical device that projects separate images into the two eyes

3. Presenting Binocular Images Various ways to add depth: –1. Stereoscope

4. Stereograms Left Eye Right Eye Divider Right eye sees face to the right; left eye sees face to the left therefore: uncrossed disparity Face appears behind the square

5. Stereograms Left Eye Right Eye Divider What would you see?

6. Stereograms Left Eye Right Eye Divider Right eye sees face to the left; left eye sees face to the right therefore: crossed disparity Face appears in front of square

7. Presenting Binocular Images Various ways to add depth: –glasses with different lenses

8. Presenting Binocular Images Various ways to add depth: –glasses with different lenses

9. Presenting Binocular Images Various ways to add depth: –glasses with different lenses

10. Presenting Binocular Images Various ways to add depth: –LCD Shutter Glasses

11. Autostereograms Optically separate images aren’t needed

12. Autostereograms Optically separate images aren’t needed WARNING! Confusing stuff coming in the next slides

13. Autostereograms Optically separate images aren’t needed WARNING! Confusing stuff coming in the next slides Keep the definitions of convergence and disparity separate.

14. Autostereograms Convergence is on a point at the same distance as the images Boxes and faces are on the horopter How many boxes would you see? boxes and faces are on the horopter

15. Autostereograms right-eye line of sight crosses left-eye line of sight in front of image (crossed convergence) each retina is now pointed at the opposite box How many boxes would you see? What would happen to the face? crossed convergence

16. Autostereograms There would be three boxes middle box: right eye sees face shifted to right; left eye sees face shifted to left therefore: uncrossed disparity Face in the middle box appears behind square crossed convergence

17. Autostereograms Left Eye’s Image Right Eye’s Image Crossed convergence shifts right image to the right of the left image and vice versa:

18. Autostereograms What would happen if the convergence was uncrossed?

19. Autostereograms Left Eye Right Eye Uncrossed convergence shifts right-eye’s image to the left of the left-eye image and vice versa:

20. Autostereograms What would happen if the faces were switched relative to the boxes?

21. Autostereograms one doesn’t even need two different images!

22. RIGHT EYELEFT EYE Convergence tells your brain that the plane of the image is farther away than it really is Autostereograms

23. Uneven spacing between identical objects in a single picture can appear as disparity if the angle of convergence is inappropriate

24. Autostereograms Uneven spacing between identical objects in a single picture can appear as disparity if the angle of convergence is inappropriate TRICK: Seeing depth in autostereograms requires you to suppress the reflexive coordination between convergence and accommodation

26. RIGHT EYELEFT EYE If you uncross convergence, your right eye gets these faces shifted slightly to left, left eye gets them shifted to right = CROSSED DISPARITY Autostereograms Any repeating objects that have a spacing different from the background will have either crossed or uncrossed disparity What would you see?

28. RIGHT EYELEFT EYE If you uncross convergence, right eye gets these faces shifted slightly to right, left eye gets them shifted to left = UNCROSSED DISPARITY Autostereograms Any repeating objects that have a spacing difference from the background will have either crossed or uncrossed disparity What would you see?

30. Autostereograms Any repeating objects that have a spacing difference from the background will have either crossed or uncrossed disparity How could you reproduce the same effects using crossed convergence?

31. Autostereograms by adjusting the disparity at different parts of the image (with a computer usually) one can make shapes that emerge or recede in depth