N328 Visualizing Information Week 3: Visual Perception Khairi - - PowerPoint PPT Presentation

▶
n328 visualizing information
SMART_READER_LITE
LIVE PREVIEW

N328 Visualizing Information Week 3: Visual Perception Khairi - - PowerPoint PPT Presentation

Nov 26, 2022 226 likes •931 views

N328 Visualizing Information Week 3: Visual Perception Khairi Reda | redak@iu.edu School of Informa5cs & Compu5ng, IUPUI Last week Attribute/Variable Types Categorical (Nominal, Qualita7ve) A finite set of categories No implicit

slide-1
SLIDE 1

N328 Visualizing Information

Khairi Reda | redak@iu.edu School of Informa5cs & Compu5ng, IUPUI

Week 3: Visual Perception

slide-2
SLIDE 2

Last week…

slide-3
SLIDE 3

Attribute/Variable Types

✦Categorical (Nominal, Qualita7ve)

A finite set of categories No implicit ordering between categories

✦Ordered

  • Ordinal

Implicit ordering between categories/levels, but no clear magnitude difference. Can compare and determine greater/less than

  • Quan7ta7ve

Meaningful magnitude Can do arithme5c

slide-4
SLIDE 4

Quan7ta7ve Data

Interval vs. Ordinal

✦ Interval

  • Zero does not indicate an absence of detectable measurement
  • We can determine distance between measurement, but not propor5ons
  • Example: temperature, dates

✦ Ra7o

  • The posi5on of zero indicates there is nothing of the measured en5ty
  • Can determine ra5o and propor5ons
  • Example: weight, age
slide-5
SLIDE 5
slide-6
SLIDE 6
slide-7
SLIDE 7

This week

Fundamentals of Visual Percep5on and Cogni5on

slide-8
SLIDE 8

Reading materials Quiz

  • Used to mark aTendance (1 point)
  • 10 minutes
  • Pass code: lemon
slide-9
SLIDE 9

Percep7on Iden5fica5on and interpreta5on of physical sensory input Cogni7on The processing of informa5on and applying knowledge Recording and retrieving informa5on from memory Percep7on: Hearing someone speak Cogni7on: Understanding words, remembering informa5on

Perception vs. Cognition

Based on a slide by Alex Lex

slide-10
SLIDE 10

Perception vs. Cognition

  • Eye, op5cal nerve, primary visual cortex
  • Basic visual features (e.g., edges,
  • rienta5on, shapes)
  • Unconscious

Perception

  • Object recogni5on
  • Rela5onship between objects
  • Remembering shapes or

paTerns

  • Learning new shapes
  • Problem solving
  • Deliberate
  • Requires aAen7on

Cognition

Based on a slide by Alex Lex

slide-11
SLIDE 11

The boundary between perception and cognition is hard to delineate

Perception -> cognition Cognition -> perception

slide-12
SLIDE 12
slide-13
SLIDE 13

Faces in Things

slide-14
SLIDE 14

Take home point

What we see is influenced by visual features

  • ur brain perceive (boTom-up) and by what

we know beforehand (top-down)

slide-15
SLIDE 15

The human visual system

Illustration from Wikipedia

slide-16
SLIDE 16

The human visual system

https://www.researchgate.net/figure/Processing-steps-of-the-visual-stream-a-The-cellular-organization-of-the-retina-from_fig1_233971662

slide-17
SLIDE 17

The human eye

http://www.fortworthastro.com/images/eye_xsection_01.jpg

light electricity

slide-18
SLIDE 18

ganglion cells rods

~120 million

highly-sensi5ve to light not sensi5ve to color good for low-light vision

cones

~5-6 million sensi5ve to color

sharp vision

require good ligh5ng

“Structure of the Mammalian Retina”, Ramon y Cajal Based on a slide by Alex Lex

slide-19
SLIDE 19

Wandell, “Foundations of Vision”

Electron microscopy of photoreceptors

slide-20
SLIDE 20

Cones types

HyperPhysics, Georgia State University

slide-21
SLIDE 21

Wikipedia

Cone distribution by pigment

normal vision color blindness (red deficiency)

slide-22
SLIDE 22

Density of rods/cones

  • E. Goldstein, “Sensation and Perception”

Adapted from Lindsay & Norman, 1977 Via Miriah Meyer

slide-23
SLIDE 23
  • C. Ware

Visual Thinking for Design

slide-24
SLIDE 24

Vision

Human vision does not work like a camera The eye makes a series of fixa7ons and saccades fixa7on: maintaining gaze over a single loca5on (200-600ms) saccade: movement between loca5ons 20-100ms

Based on a slide by Alex Lex

slide-25
SLIDE 25

Visual Illusions

slide-26
SLIDE 26
slide-27
SLIDE 27

Via Miriah Meyer

slide-28
SLIDE 28

Via Miriah Meyer

slide-29
SLIDE 29
slide-30
SLIDE 30

Cornsweet illusion

slide-31
SLIDE 31

Visual perception is relative

slide-32
SLIDE 32

Visual perception is relative

Differences in color are rela5ve

slide-33
SLIDE 33

Visual perception is relative

Differences in contrast is rela5ve

slide-34
SLIDE 34

Visual perception is relative

Color interac5on

Wong 2010 Via Miriah Meyer

slide-35
SLIDE 35

Visual perception is relative

Sizes are rela5ve (Ames room)

slide-36
SLIDE 36

Take home point

Our visual system see differences, not absolute values.

Based on a slide by Miriah Meyer

slide-37
SLIDE 37

Design critique

http://tinyurl.com/6mu8h63

  • What is the visualiza5on

about?

  • What data is represented in

the visualiza5on? And how?

  • What are the interac5ons

used?

  • What ques5ons can we

answer with the visualiza5on?

  • Do you like the visualiza5on?
  • Are there any improvements

that can be made to the design?

slide-38
SLIDE 38

POPOUT

slide-39
SLIDE 39

which side has the outlier?

slide-40
SLIDE 40

which side has the outlier?

  • C. Healey, 2007
slide-41
SLIDE 41

which side has the outlier?

  • C. Healey, 2007
slide-42
SLIDE 42

which side has the outlier?

  • C. Healey, 2007

use a single popout channel at a time (e.g., either difference in color or shape alone) to draw attention

slide-43
SLIDE 43

Popout channels

no popout

  • C. Ware

“Information Visualization”

slide-44
SLIDE 44

Semantic Depth of Field

  • C. Ware

“Information Visualization”

slide-45
SLIDE 45
  • R. Kosara

Semantic Depth of Field

slide-46
SLIDE 46

Popout / pre-attentive processing

  • Very fast at grabbing aTen5on (less than 200 milli

seconds)

  • Popout elements have to be salient compared to

surrounding

  • Elements that are a conjunc7on of mul5ple channels
  • gen do not pop out
slide-47
SLIDE 47

How does pre-aAen7ve processing / pop outs work?

We don’t know for sure, but there are some theories:

https://www.csc.ncsu.edu/faculty/healey/PP/ index.html#Preattentive_Theory

slide-48
SLIDE 48

Take home point

We can easily see objects that are different in color and shape, or that are in mo5on

Based on slides by Miriah Meyer & Alex Lex

Use color and shape sparingly to make the important informa5on pop out Visual features must be carefully designed. Conjunc5ons must be avoided, if popout is desired

slide-49
SLIDE 49

Gestalt grouping principles

slide-50
SLIDE 50

Gestalt grouping principles

“The whole is other than the sum of its parts”

Our brain has innate capacity to see paTerns that transcend the visual s5muli the produce them

gestalt: form in German

slide-51
SLIDE 51

proximity

Andy Rutledge, “Gestalt Principles of Perception”

slide-52
SLIDE 52

proximity

Alex Lex

slide-53
SLIDE 53

proximity

  • B. Wong, “Gestalt Principles, I”
slide-54
SLIDE 54

similarity

  • B. Wong, “Gestalt Principles, I”
slide-55
SLIDE 55

similarity

Andy Rutledge, “Gestalt Principles of Perception”

slide-56
SLIDE 56

connectedness

Ware, “Information Visualization”

slide-57
SLIDE 57

link surface

  • utline

enclosure

Alex Lex

slide-58
SLIDE 58

A liAle experiment…

Based on a slide by Alex Lex

How many groups do you see?

proximity color similarity size similarity shape similarity

slide-59
SLIDE 59

A liAle experiment…

How many groups do you see?

proximity color similarity size similarity shape similarity

Based on a slide by Alex Lex

slide-60
SLIDE 60

A liAle experiment…

How many groups do you see?

proximity color similarity size similarity shape similarity

Based on a slide by Alex Lex

slide-61
SLIDE 61

grouping

  • B. Wong, “Gestalt Principles, I”
slide-62
SLIDE 62

grouping

slide-63
SLIDE 63

grouping

Jorge Camoes Via Miriah Meyer

slide-64
SLIDE 64

grouping - common fate

slide-65
SLIDE 65

closure

slide-66
SLIDE 66

closure

slide-67
SLIDE 67

figure / background

Mariah Meyer

slide-68
SLIDE 68

Gestalt principles

similarity: objects that look like each other (in size, color, or shape) are related proximity: objects that are visually close to each

  • ther are related

connections: objects that are visually connected are related closure: we see incomplete shapes as complete figure / ground: elements are perceived as either figures or background common fate: elements with the same moving direc5on are perceived as a unit

Mariah Meyer

slide-69
SLIDE 69

next week…

color perception