Leture3_HCI and Interactivity

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  • Overview of

    Multimedia and

    Human Computer

    Interfaces

    Multimedia Interfaces

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  • Outline

    Human Computer Interface.

    Multimedia interfaces and applications.

    Vision based interfaces

    Systems using vision based interfaces.

    Some basic methods in vision interfaces

    Background subtraction.

    Color blob detection and tracking.

    Face detection (Viola and Jones face detector).

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  • Human Computer Interface

    Different meanings of HCI

    The study of people, computer technology and the ways they interactive with each

    other.

    The design, evaluation and implementation of computer systems for human use.

    The research to study how to make computer systems more useable.

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  • Aspects of HCI

    Design

    Intuition, experiences and design principles.

    Human factors

    Experiments testing the perception, memory and cognition models of human being.

    Devices

    Physical devices such as mouse, keyboards and other fancy HCI hardware.

    Software and systems

    Such as windows GUI, shell commands in Unix etc.

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  • HCI Studies

    Computers

    What are they good at and bad at?

    Input, output, processing, networking, etc.

    People

    What are people good at?

    What is the limitation of human abilities?

    Input, output, memory, perception and cognition model.

    No average answer. Must accommodate diversities.

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  • HCI Studies

    Usability

    More than the size of widgets, where are the buttons and syntax of commands.

    Context

    Environment, physical constraints, cognition constraints, task, etc.

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  • The Quality of HCI

    There are fives factors that affect the design and implementation of HCI

    Time to learn.

    Speed of performance.

    Rate of errors.

    Retention over time.

    Subjective satisfaction.

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  • Technology-driven vs.

    user-centred design

    You can have different starting points:

    The technology runs the design of the interface which give the user the functionality of the system

    Users put demands on the functionality of the interface which runs the design of the technology

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  • Human-Computer Interaction

    Human-computer interaction is a discipline

    concerned with the design, evaluation and

    implementation of interactive computing

    systems for human use and with the study of

    major phenomena surrounding them.

    - (ACM SIGCHI, 1992, p. 6)

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  • Disciplines contributing to

    and benefiting from HCI

    Computer science

    Cognitive psychology

    Social and organizational psychology

    Ergonomics or human factors

    Interaction design

    Linguistics

    Artificial intelligence

    Philosophy, sociology and anthropology

    Engineering

    Design

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  • HCI

    The fundamental goals of HCI: to develoor improve the safety, utility, effectiveness,

    efficiency, and Usability of systems that include

    computers (Interacting with Computers, 1989, p. 3)

    Safety (design of safety-critical systems), utility

    (the functionality of a system), usability

    (making systems easy to learn and easy

    to use)

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  • HCI

    Key concept in HCI

    Can be broken down into the following goals:

    Effective to use (effectiveness)

    Efficient to use (efficiency)

    Safe to use (safety)

    Have good utility (utility, functionality)

    Easy to learn (learnability)

    Easy to remember how to use (memorability)

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  • Interaction (with or without computer) is a process of information transfer.

    The diversity of devices reflects the fact that there are many different types of data that

    may be entered into and obtained from a

    system, as there are many different users.

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  • In the early days, batch processing was common: a large mass of information was

    dumped into and processed by the computer.

    Nowadays, computers respond within milliseconds and computer systems are

    integrated in many different devices

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  • text entry devices

    keyboards (QWERTY et al.) chord keyboards, phone pads

    handwriting, speech

  • Keyboards

    Most common text input device

    Allows rapid entry of text by experienced users

    Keypress closes connection, causing a character code to be sent

    Usually connected by cable, but can be wireless

  • layout QWERTY

    Standardised layout

    but non-alphanumeric keys are placed differently

    accented symbols needed for different scripts

    minor differences between UK and USA keyboards

    QWERTY arrangement not optimal for typing layout to prevent typewriters jamming!

    Alternative designs allow faster typing but large social base of QWERTY typists produces

    reluctance to change.

  • QWERTY (ctd)

    2 3 4 5 6 7 8 9 0

    Q W E R T Y U I

    1

    O P

    S D F H J LA G K

    Z X C V B N M , .

    SPACE

  • alternative keyboard layouts

    Alphabetic keys arranged in alphabetic order

    not faster for trained typists

    not faster for beginners either!

    Dvorak common letters under dominant fingers

    biased towards right hand

    common combinations of letters alternate between hands

    10-15% improvement in speed and reduction in fatigue

    But - large social base of QWERTY typists produce market pressures not to change

  • Chord keyboards

    only a few keys - four or 5

    letters typed as combination of keypresses

    compact size

    ideal for portable applications

    short learning time

    keypresses reflect letter shape

    fast

    once you have trained

    BUT - social resistance, plus fatigue after extended use

    NEW niche market for some wearables

  • phone pad and T9 entry

    use numeric keys with multiple presses 2 a b c 6 - m n o

    3 - d e f 7 - p q r s

    4 - g h i 8 - t u v

    5 - j k l 9 - w x y z

    hello = 4433555[pause]555666

    surprisingly fast!

    T9 predictive entry type as if single key for each letter

    use dictionary to guess the right word

    hello = 43556

    but 26 -> menu am or an

  • Handwriting recognition

    Text can be input into the computer, using a pen and a digesting tablet natural interaction

    Technical problems: capturing all useful information - stroke path, pressure,

    etc. in a natural manner

    segmenting joined up writing into individual letters

    interpreting individual letters

    coping with different styles of handwriting

    Used in PDAs, and tablet computers leave the keyboard on the desk!

  • Speech recognition

    Improving rapidly

    Most successful when:

    single user initial training and learns peculiarities

    limited vocabulary systems

    Problems with

    external noise interfering

    imprecision of pronunciation

    large vocabularies

    different speakers

  • Numeric keypads

    for entering numbers quickly:

    calculator, PC keyboard

    for telephones

    not the same!!

    ATM like phone

    4 5 6

    7 8 9

    * 0 #

    1 2 3

    4 5 6

    1 2 3

    0 . =

    7 8 9

    telephone calculator

  • positioning, pointing

    and drawing mouse, touchpad trackballs, joysticks etc. touch screens, tablets eyegaze, cursors

  • the Mouse

    Handheld pointing device

    very common

    easy to use

    Two characteristics

    planar movement

    buttons (usually from 1 to 3 buttons on top, used for making a selection, indicating an option, or to initiate drawing etc.)

  • the mouse (ctd)

    Mouse located on desktop requires physical space

    no arm fatigue

    Relative movement only is detectable.

    Movement of mouse moves screen cursor

    Screen cursor oriented in (x, y) plane, mouse movement in (x, z) plane

    an indirect manipulation device.

    device itself doesnt obscure screen, is accurate and fast.

    hand-eye coordination problems for novice users

  • How does it work?

    Two methods for detecting motion

    Mechanical Ball on underside of mouse turns as mouse is moved

    Rotates orthogonal potentiometers

    Can be used on almost any flat surface

    Optical light emitting diode on underside of mouse

    may use special grid-like pad or just on desk

    less susceptible to dust and dirt

    detects fluctuating alterations in reflected light intensity to calculate relative motion in (x, z) plane

  • Even by foot

    some experiments with the footmouse

    controlling mouse movement with feet

    not very common :-)

    but foot controls are common elsewhere:

    car pedals

    sewing machine speed control

    organ and piano pedals

  • Touchpad

    small touch sensitive tablets

    stroke to move mouse pointer

    used mainly in laptop computers

    good acceleration settings important fast stroke

    lots of pixels per inch moved

    initial movement to the target

    slow stroke less pixels per inch

    for accurate positioning

  • Trackball and thumbwheels

    Trackball ball is rotated inside static housing

    like an upsdie down mouse!

    relative motion moves cursor

    indirect device, fairly accurate

    separate buttons for picking

    very fast for gaming

    used in some portable and notebook computers.

    Thumbwheels for accurate CAD two dials for X-Y cursor position

    for fast scrolling single dial on mouse

  • Joystick and keyboard

    nipple Joystick

    indirect pressure of stick = velocity of movement

    buttons for selection on top or on front like a trigger

    often used for computer games aircraft controls and 3D navigation

    Keyboard nipple

    for laptop computers

    miniature joystick in the middle of the keyboard

  • Touch-sensitive screen Detect the presence of finger or stylus on the

    screen. works by interrupting matrix of light beams, capacitance

    changes or ultrasonic reflections

    direct pointing device

    Advantages: fast, and requires no specialised pointer

    good for menu selection

    suitable for use in hostile environment: clean and safe from damage.

    Disadvantages: finger can mark screen

    imprecise (finger is a fairly blunt instrument!) difficult to select small regions or perform accurate drawing

    lifting arm can be tiring

  • Stylus and light pen

    Stylus

    small pen-like pointer to draw directly on screen

    may use touch sensitive surface or magnetic detection

    used in PDA, tablets PCs and drawing tables

    Light Pen

    now rarely used

    uses light from screen to detect location

    BOTH very direct and obvious to use

    but can obscure screen

  • Digitizing tablet

    Mouse like-device with cross hairs

    used on special surface - rather like stylus

    very accurate - used for digitizing maps

  • Eyegaze

    control interface by eye gaze direction e.g. look at a menu item to select it

    uses laser beam reflected off retina a very low power laser!

    mainly used for evaluation (ch x)

    potential for hands-free control

    high accuracy requires headset

    cheaper and lower accuracy devices available sit under the screen like a small webcam

  • Cursor keys

    Four keys (up, down, left, right) on keyboard.

    Very, very cheap, but slow.

    Useful for not much more than basic motion for text-editing tasks.

    No standardised layout, but inverted T, most common

  • Discrete positioning controls

    in phones, TV controls etc.

    cursor pads or mini-joysticks

    discrete left-right, up-down

    mainly for menu selection

  • Multimedia Interfaces Multimedia interface

    combines different sorts of

    media modalities to achieve

    more natural and more

    efficient human computer

    communication.

    Speech, audio, touch, video input (patterns, posture,

    gesture) etc.

    Put that there is an example multimedia HCI that

    combines speech, gestures

    and graphics.

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    http://www.media.mit.edu/speech/sig_videos.html

    Put that there, MIT 1981

  • Early and Late Integration

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    Mode 1

    Mode 2

    Classification Features Output

    Mode 1

    Mode 2

    Features

    Classification

    Output

    Classification

    Early integration

    Late integration

  • Advantages of Multimedia

    Interface More alternative methods.

    The flexibility of combining different schemes.

    More efficient for specific tasks.

    Greater precision of information.

    Help handicapped people to use computers.

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    http://www.youtube.com/watch?v=d7eGypGOlOc&feature=related http://www.youtube.com/watch?v=Gnq-8iaOcXk

    Pen gesture interface Virtual Reality

  • Vision Based Interfaces

    Vision based interfaces uses computer vision techniques to achieve more effective HCI.

    Vision based interfaces are based on techniques such as:

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    Hand tracking,

    Hand gesture,

    Arm gesture

    Hand Pointing

    Face detection

    Head tracking

    Gaze

    Expression

    Lip reading Posture, body gesture and

    action recognition

  • Example Systems

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    Motion

    Capturing

  • Example Systems

    The MIT Kidsroom

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    Posture recognition

    Action

    detection

  • Methods in Vision Interfaces

    Background subtraction.

    Estimating the background

    B(n) = B(n)*alpha + I(n)*(1-alpha)

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    Foreground Map = |Image Background|>threshold

    alpha is a positive floating point number close to 1.

  • Color Blob Detection

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    We would like to compare the template color

    histogram with each location in the image.

    (x,y)

    h(x,y) is the color histogram

    a b

    c d

  • Mean Shift Tracking

    Instead of exhaustive search in a window, if object moves slowly, we can use a more

    efficient location updating scheme Mean shift.

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  • Mean Shift Tracking Result

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    http://www.caip.rutgers.edu/~comanici/Papers/KernelTracking.pdf

  • Face Detection Viola and Jones face detector

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    These features can be computed using integral images similarly

    to the color histograms discussed before.

  • Face Detection

    It uses boosting scheme to automatically choose the optimal weight for the classifier

    based on each kind of feature.

    To further improve the efficiency, a cascaded classifier is used.

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  • Why HCI is important? In order to achieve efficient, effective and safe products/systems:

    Productivity (introducing technology that does not support the work may cause

    reduced productivity)

    Safety (crashed air planes and nuclear power plant disasters have led to an understanding why

    HCI is important!)

    Computers should be designed for the needs and capabilities of the

    people for whom they are intended!

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  • Summary

    We only touched the very surface of multimedia interfaces.

    Currently, the dominant HCI is still GUI with keyboard and mouse.

    Multimedia interfaces are beginning to attract more and more interests.

    We need more robust and efficient media recognition schemes to support effective

    multimedia interfaces. CS335 P

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