2. ch 101 Sensation & Perception Ch. 10: Perceiving depth and size © Takashi Yamauchi (Dept. of Psychology, Texas A&M University) Main topics Monocular depth cues Binocular depth cues Visual illusion The physiology of depth perception

3. ch 102 Tell me why these pictures look bizarre?

4. ch 103 Escher: Ascending

5. ch 104 Belvedere : Escher

6. ch 105 Red Ants: Escher

7. ch 106 Relativity: Escher

8. ch 107 Up and Down: Escher

9. ch 108 Waterfall: Escher

10. ch 109

11. 10 De Chirico

12. ch 1011 Why do these paintings evoke a strange feeling?

13. ch 1012 Leonardo da Vinci (1452-1519) There has never been an artist who was more fittingly, and without qualification, described as a genius. Like Shakespeare, Leonardo were from an insignificant background and rose to universal acclaim. Leonardo was the illegitimate son of a local lawyer in the small town of Vinci in the Tuscan region…. Mona Lisa (1503)

14. ch 1013 The Dreyfus Madonna: da Vinci 1469

15. ch 1014 Why did Leonardo become so famous? One secret:

16. ch 1015 The Last Supper: da Vinci, 1498

17. ch 1016 The virgin of the rocks: da Vinci, 1483- 1486

18. ch 1017 Madonna Litta: (da Vinci) 1490-1491

19. ch 1018 The Santa Trinita Madonna: Cimabue (1260/80)

20. ch 1019 Coronation of the virgin altarpiece from San Domenico: Fra Angelico, 1434

21. ch 1020 The presentatio n of the virgin: Giotto, 1305

22. ch 1021 Madonna in Glory: Giotto, 1311

23. ch 1022 Why did Leonardo become so famous? Or what made Leonardo’s pictures so special?

24. ch 1023 1469 1260/80 1311 1434 2000 Historical depiction of Madonna

25. ch 1024 1469 1260/80 1311 1434 2000 Historical depiction of Madonna

26. ch 1025

27. ch 1026 What I think: Everything before Leonardo was very flat. These pictures were so crisp clear. No ambiguity. Leonardo (A-rod) made things more ambiguous.

28. ch 1027 Leonardo found two tricks To depict distance, L used (but not W, definitely not A-rod) –Linear perspective –Atmospheric perspective

29. ch 1028 Leonardo used lots of pictorial cues to depict depth

30. ch 1029 Atmospheric perspective Things get vague when they are away.

31. ch 1030 Things get smaller when they are away.

32. ch 1031 Linear perspective Things get smaller when they are away.

33. ch 1032 Linear perspective Linear perspective is very “Renaissance.” Renaissance  humanism  free from feudalism (religious bigotry) Put a person at the center of the world. –Not religious authority

34. ch 1033 Other quintessential Renaissance men are Descartes (1590-1650) –I think therefore I am. (“I” is the center). Linear perspective is a pictorial version of “I think therefore I am.” (my idiosyncratic interpretation). Why?

35. ch 1034 Linear perspective is about putting yourself at the center of the physical world. and arrange everything else based on that center. It is about reproducing the relationship between you, the painter, and the other objects in the world in pictorial space.

36. ch 1035 Monocular pictorial cues Occlusion Relative height Relative size Familiar size Atmospheric perspective Linear perspective

37. ch 1036 Occlusion

38. ch 1037 Relative height

39. ch 1038 Relative size

40. ch 1039 Atmospheric perspective

41. ch 1040

42. ch 1041

43. ch 1042

44. ch 1043 Texture gradient

45. ch 1044

46. ch 1045 These cues are something you notice everyday in the physical world. The visual system uses these cues and generates depth perception naturally. –You don’t need to think about them. They are just there.

47. ch 1046 Visual Illusions

48. ch 1047 (A) (B) (A) (B)

49. ch 1048

50. ch 1049

51. ch 1050

52. ch 1051

53. ch 1052 Tell me why these pictures bizarre? Any idea?

54. ch 1053 What makes these pictures surreal?

55. ch 1054 What makes these pictures surreal?

56. ch 1055 Any idea?

57. ch 1056 My guess: These pictures deliberately violate pictorial cues. –  which evokes a strange feeling. –  these pictures depict impossible scenes by reversing depth relations.

58. ch 1057 Violating some depth cues –Deliberately introducing contradictory depth information.

59. ch 1058 What makes these pictures surreal? Violating linear perspective

60. ch 1059

61. ch 1060

62. ch 1061

63. ch 1062 How to make an Escher figure.

64. ch 1063

65. ch 1064 Other cues Movement parallax –Nearby objects move faster than distant objects –http://video.google.com/videoplay?docid=- 5983729407150064898&q=motion+parallax&t otal=43&start=0&num=10&so=0&type=search &plindex=2

66. ch 1065 Visual Illusions http://users.skynet.be/J.Beever/pave.htm http://www.magiceye.com/ Ames room (1:13) –http://www.youtube.com/watch?v=Ttd0YjXF0 no&feature=relatedhttp://www.youtube.com/watch?v=Ttd0YjXF0 no&feature=related Star wars: Attack of the clones (10 min) –http://www.youtube.com/watch?v=3VEdD8QO lGk

67. ch 1066

68. ch 1067

69. ch 1068 http://www.greatbuil dings.com/buildings/ Guggenheim_Bilbao. html

70. ch 1069 Binocular Depth Information

71. ch 1070 Why do we have two eyes? Long, long time ago, we used to have one eye or no eye at all. Now we have two eyes. How come?

72. ch 1071 Before I guess we were all like these. Now We got two eyes. How come? And then

73. ch 1072 Something to do with evolution? Some kind of evolutionary force Having two eyes is evolutionarily advantageous? What advantage is it?

74. ch 1073 What eyes are for? –The eye is a sensor. –It is about detecting things in the world. –Eyes used to be part of “skin.” –some part of skin (cell body, membrane) became particularly sensitive to light. –And eventually that part developed to possess eye-like functions.

75. ch 1074 We got two ears, two nostrils as well. The same thing is true for ears, and probably for nostrils, too. –But not for the mouth. Two eyes, two ears, and two nostrils help the organism to locate things in the 3-D world

76. ch 1075 Binocular depth cues Ever visited an IMAX theater? Or some special planetarium? –Wearing special sunglasses and see a large screen. –You get an incredible 3-D effect.

77. ch 1076

78. ch 1077 Binocular disparity & Binocular depth cues

79. ch 1078 Demo Step 1: Hold your one finger about 8 inches in front of you and the other about 15 inches in front of you. Step 2: Focus on the one that is further from you, and move the other finger back and forth. Got double images for the unfocused finger? But why?

80. ch 1079 Binocular disparity Your two eyes are getting different images  disparity  double images Corresponding points No disparitydisparity

81. ch 1080 Small disparity Large disparityNo disparity

82. ch 1081 Horopter (Vieth- Muller circle)

83. ch 1082 Binocular disparity The binocular disparity arises when a given point in the external world does not project to the corresponding points on the left and right retinae –(Palmer, 1999, “Vision Science”)

84. ch 1083 Binocular disparity -  OK, then open your right eye and close your left eye. What happens? Repeat this several times.

85. ch 1084 Binocular disparity -  OK, then open your right eye and close your left eye. What happens? Repeat this several times.

86. ch 1085 Do the same thing several times. This time change the distance between your focused and unfocused fingers. –When your unfocused finger is close to you, –That finger moves further left.

87. ch 1086 Your unfocused finger moves to the left. Why?

88. ch 1087 Small disparity large disparity small distance large distance

89. ch 1088 Binocular disparity The amount of disparity can tell us how far an object is apart from the object you are focusing on. But how do we know the unfocused objects is farther from or closer to you?

90. ch 1089 2 types of disparity P F P C crossed disparity uncrossed disparity

91. ch 1090 P falls on the foveae of both eyes, so they stimulate corresponding points. Both F and C do not fall on the corresponding points. C is close, and the disparity goes outward. –  “Crossed disparity” F is farther, and the disparity goes inward. –  “uncrossed disparity” These two types of disparity signals the brain whether the object is close to or far from you.

92. ch 1091 Where? Binocular depth cue  you need two eyes V1 (striate cortex is the first location where the information from the two eyes is merged). Specific neurons in V1, V2 and V3 respond to disparity.

93. ch 1092 Emmert’s law S = R x D –S: Perceived size –R: retinal image –D: perceived distance

94. ch 1093 Fig. 10-33, p. 248