INDE 599B: VISUALIZATION AND ANALYTICS

1. INDE 599B: VISUALIZATION AND ANALYTICS SOME BASIC VISUAL PROCESSES DON PARKER

2. THEME “DOIN’ WHAT COMES NATURALLY” -- WHAT’S BUILT INTO THE ADULT VISUAL PERCEPTION SYSTEM THAT COULD FACILTATE VISUAL ANALYSIS?

3. TOPICS • INTRODUCTION • BASIC VISUAL PHYSIOLOGY • 3D PERCEPTION • BASIC GESTALT ORGANIZING PRINCIPLES • ORIENTATION: GRAVITY, LIGHT SOURCE • IMPORTANCE OF MOTION: • BOTTOM-UP VS TOP-DOWN PROCESSES • MULTI SENSORY PROCESSES • VISUAL SEARCH

4. INTRODUCTION PHI (APPARENT MOVEMENT) PHENOMENON “WHAT THE FROG’S EYE TELLS THE FROG’S BRAIN” PERSPECTIVE TRANSFORMATIONS A NEW CAREER

5. PHI • http://images.google.com/imgres?imgurl=http://www.aber.ac.uk/media/Modules/MC10220/Images/beta_movement.gif&imgrefurl=http://www.aber.ac.uk/media/Modules/MC10220/visper08.html&h=256&w=320&sz=4&hl=en&start=9&tbnid=bVo5oQwjpIL_WM:&tbnh=94&tbnw=118&prev=/images%3Fq%3Dapparent%2Bmotion%2Bphi%2Bphenomenon%26gbv%3D2%26svnum%3D10%26hl%3Den%26sa%3DG

6. PHI ANNIMATION Notice that a series of white dots appear to blink on and off in sequence against a blue background. Also notice that a "phantom" dot, the same color as the background, appears to chase around the circle in an anti clockwise direction. The lower figure shows a phantom white dot chasing around a blue circle.

7. FLIPPPING KANIZSA • http://www.settheory.com/Glass_paper/flipping_kanizsa.gif

8. “WHAT THE FROG’S EYE TELLS THE FROG’S BRAIN”

9. DOME PAT – TEACH ASTRONAUTS PERSPECTIVE TRANSFORMATIONS

10. Sensation Sensory Systems • Sight (Vision) • stimulus • light waves • sense organ • eye • receptor • rods and cones of retina • sensation • patterns • textures • motion • depth

11. Sensation Sensory Systems • Sight (Vision) • sensation • colors • hue • wavelength • brightness • intensity • saturation • purity

12. Sensation Sensory Systems • Sight (Vision)

13. Sensation Sensory Systems • Sight (Vision) • Color Vision • Three Cone Types • 3 Color Channels • Convergence • Opponent Process • Upstream • Inhibition • Excitation

14. Sensation Sensory Systems • Sight (Vision)

15. LATERAL INHIBITION

16. 3D PERCEPTION STATIC • Perception of Depth • Monocular cues - only need one eye; e.g., lens accommodation • Binocular cues - two eyes • Binocular Cues • disparity • image slightly different on each eye • vergence • eyes must turn toward each other to see close objects

17. ACCOMMODATION

18. VERGENCE (Pare)

19. ACCOMMODATION – VERGENCE MISMATCH • HMD • DISTURBANCE • “TRUE” 3D

20. DISPARITY

21. Perception Depth • Monocular cues • linear perspective • parallel lines converge with depth • size • large objects become smaller with distance • Ponzo Illusion

22. Perception Depth • Some monocular cues • overlap (AKA interposition) • fully exposed figure is perceived as being closer • aerial perspective (atmospheric perspective) • blur increases with depth • texture • coarse - near • fine - far

23. 3D PERCEPTION --DYNAMICMONOCULAR DEPTH CUES (SELECTED)– * Kinetic occlusion / dis-occlusion * Motion perspective (motion gradients in optical array) * Motion parallax * depth-dependent flow velocity; * focus –dependent flow direction

24. HEAD MOTION PARALLAX COVERING / UNCOVERING

25. Occlusion – Dis-occlusion • Depth is perceived where moving objects transiently * (partially) occlude other objects • cast shadows on each other

26. INTERACTIVE DYNAMIC OCCLUSION -- DIS-OCCLUSION Rotating cone: http://www.michaelbach.de/ot/mot_ske/index.html

27. Motion Parallax 1 • When move head in translation, things that are further away slide across the retina more slowly.

28. DEPTH FROM OPTICAL FLOW VECTORS

29. MOTION PARALLAX OPTICAL FLOW DIRECTION RELATIVE TO FIXATION

30. Rotating Sphere 2 • FORM AND DEPTH FROM MOVEMENT OF RANDON DOTS • http://www.michaelbach.de/ot/col_equilu/index.html

31. Perception shape and form • figure - ground • parts of the visual field stand out • figure • part that stands out • ground (background) • rest • shapes and forms stand out against a background

32. Perception shape and form

33. Perception figure-ground • figure • 1. has shape • 2. is seen as a "thing" • 3. is the object of attention • 4. is usually seen as nearer than the ground • 5. often defined by contours • luminance contour • edges defined by changes in luminance • subjective contours • AKA cognitive contour • AKA illusory contour

34. Perception Figure-Ground • How do we choose a figure? • Gestalt (form) psychology • Max Wertheimer • Wolfgang Kohler • Kurt Koffka • Law of Pragnanz • “problem solving” – impose model on data • resolution of lightness contrasts into figural units tends to be • precise • simple

35. Perception Gestalt Psychology • Underlying principles (rules) • closure (AKA closedness) • fill in the gaps in an otherwise continuous pattern • closed contours stand out • continuity (AKA good continuation) • elements of interesting patterns group together • figure = set of contrasts that makes the fewest deviations from a straight line or simple curve • proximity • close together go together

36. Perception Gestalt Psychology • Underlying principles (rules) • closure (AKA closedness) • fill in the gaps in an otherwise continuous pattern • closed contours stand out

37. Perception Gestalt Psychology • Underlying principles (rules) • continuity (AKA good continuation) • elements of interesting patterns group together • figure = set of contrasts that makes the fewest deviations from a straight line or simple curve

38. Perception Gestalt Psychology • Underlying principles (rules) • proximity • close together go together

39. Perception Gestalt Psychology • Underlying principles (rules) • symmetry • regular objects seen as figures • similarity • similar objects group together • common fate • we group elements that move together • experience or familiarity • we group elements based on experience

40. Perception Gestalt Psychology • Underlying principles (rules) • symmetry • regular objects seen as figures

41. Perception Gestalt Psychology • Underlying principles (rules) • similarity • similar objects group together

43. Figure 6‑4. RSSQ Total scores from the 12 subjects were separated into lower and higher SS susceptibility groups by partitioning around mediods.

44. Perception Gestalt Psychology • Underlying principles (rules) • common fate • we group elements that move together

45. Perception Gestalt Psychology • Underlying principles (rules) • experience or familiarity • we group elements based on experience CATDOG

46. Perception misapplied constancy • misapplied constancy • we have a perception that is in error • based on our rules of perception • Ames Room (Adelbert Ames) • illusory walls are closer and perpendicular • actual walls are angled • actual windows and doors are distorted

47. Perception misapplied constancy • Muller-Lyer Illusion • arrows out are interpreted as a close exterior corner • arrows in are a far exterior corner • equal lines appear larger or smaller based on the perception of distance • longer if farther away, shorter if closer

48. Perception misapplied constancy

49. Perception • Perception is a creative process • Based on learning? • Perceptual Adaptation • Von Helmholtz (1962) • prisms • shift the world • reaching • eyes open or closed • perception has been adapted

50. Perception “Pre-programmedlearning” • Imprinting geese, Lorenz • Phoneme recognition, Pat Kuhl • IMPLICATION: Train observers: • Image transformation • Shape / object recognition