Week 4

Question 1

A computer system is made up of various elements?

Answer 1

Input devices
Output devices
Virtual reality
Physical interaction
Paper
Memory
Processing

Question 2

A typical computer system?

Answer 2

screen or monitor
Keyboard
Mouse/Trackpad

Question 3

Text entry devices?

Answer 3

Keyboards
Chord keyboards, phone pads
Handwriting, speech

Question 4

QWERTY?

Answer 4

Standardized layout

arrangement not optimal for typing

Question 5

DVORAK?

Answer 5

Biased towards right hand

10-15% improvement in speed and reduction in fatigue

Question 6

Chord Keyboards?

Answer 6

Only a few keys - four or 5
Compact size
Short learning time
Fast

Question 7

Speech Recognition?

Answer 7

Improving rapidly
Most successful when
- Single user
- Limited vocabulary systems

Question 8

Problems with Speech Recognition?

Answer 8

External noise interfering
Imprecision of pronunciation
Large vocabularies
Different speakers

Question 9

Positioning, pointing and drawing?

Answer 9

Mouse, touchpad
Trackballs, joysticks
Touch screens, tablets
Eyegaze, cursors

Question 10

Mouse?

Answer 10

Two characteristics

• Planar movements
• Buttons

Question 11

Two methods for detecting motion?

Answer 11

Mechanical

Optical

Question 12

Who developed first mouse?

Answer 12

Douglas Engelbart

Question 13

Touchpad?

Answer 13

Small touch sensitive tablets
Stroke to move mouse pointer
Used mainly in laptop computers

Question 14

Advantages of touch sensitive screen?

Answer 14

Fast, and requires no specialized pointer
Good for menu selection
Suitable for use in hostile environment: clean and safe from damage

Question 15

Disadvantages of touch sensitive screen?

Answer 15

Finger can mark screen
Imprecise
Lifting arm can be tiring

Question 16

Eyegaze?

Answer 16

Control interface by eye gaze direction
User laser beam reflected off retina
Mainly used for evaluation

Question 17

Display Devices?

Answer 17

Bitmap screens
Large & situated displays
Digital paper

Question 18

Bitmap displays?

Answer 18

Screen is vast number of coloured dots

Question 19

Aspect Ratio?

Answer 19

Ratio between width and height

4:3 for most screens, 16:9 for wide-screen TV.

Question 20

Colour Depth?

Answer 20

How many different colours for each pixel
Black/white or greys only
256 from a pallete

Question 21

Jaggies?

Answer 21

Diagonal lines that have discontinuities in due to horizontal faster scan process

Question 22

Anti-Aliasing?

Answer 22

Softens edges by using shades of line colour

Also used for text

Question 23

Liquid crystal displays?

Answer 23

Smaller, Lighter and no radiation problems
Found on PDAs, portables and notebooks
Also used in digital watches, mobile phones

Question 24

How liquid crystal display works?

Answer 24

top plate transparent and polarized, bottom plate reflecting.
Light passes through top plate and crystal, and reflects back to eye.

Question 25

Special Displays?

Answer 25

Random Scan

Direct View Storage Tube

Question 26

Situated Displays?

Answer 26

Displays in public places
Display only
Or interactive
In all cases the location matters

Question 27

Virtual Reality and 3D Interaction?

Answer 27

Positioning in 3D space
Moving and grasping
Seeing 3D (Helmets and Caves)

Question 28

Positioning in 3D space?

Answer 28

Cockpit and virtual controls
The 3D mouse
Data glove
VR Helmets
Whole body tracking

Question 29

3D Displays?

Answer 29

Desktop VR

Seeing in 3D

Question 30

VR Headsets?

Answer 30

Small TV screen for each eye
Slightly different angles
3D effect

Question 31

VR Motion Sickness?

Answer 31

Time delay
Depth perception
Conflicting cues => sickness

Question 32

Time delay?

Answer 32

Move head… lag .. display moves

Conflict: head movement vs eyes

Question 33

Depth perception?

Answer 33

Headset gives different stereo distance
But all focused in same plane
Conflict: eye angle vs focus

Question 34

Conflicting cues => Sickness

Answer 34

Helps motivate improvements in technology