HCI Quiz 2 Flashcards
The computer
– text entry and pointing
input devices
– screen (small & large), digital paper
output devices
– special interaction and display devices
virtual reality
– e.g. sound, haptic, bio-sensing
physical interaction
as output (print) and input (scan)
paper
– RAM & permanent media, capacity & access
memory
short-term memory:
Random Access Memory (RAM)
long-term memory:
magnetic and optical disks, USB, hard drives
– speed of processing, networks
processing
The most common text input device
Allows rapid entry of text by experienced users
Keyboards
keys arranged in alphabetic order
not faster for trained typists
not faster for beginners either!
Alphabetic
-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
Dvorak
designs to reduce fatigue for Repetitive Strain Injury
for one-handed use
e.g. the Maltron left-handed keyboard
special 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
Chord keyboards
use numeric keys withmultiple 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
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’
phone pad and T9 entry
Text can be input into the computer, using a pen and a digesting tablet
natural interaction
Handwriting recognition
Most successful when:
single user – initial training and learns peculiarities
limited vocabulary systems
Speech recognition
for entering numbers quickly:
calculator, PC keyboard
for telephones
Numeric keypads
Handheld pointing device
Two characteristics
planar movement
buttons
the Mouse
Mouse located on desktop requires physical space with no arm fatigue. Relative movement only is detectable
true
Ball on the underside of mouse turns as mouse is moved
Rotates orthogonal potentiometers
Can be used on almost any flat surface
Mechanical mouse
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
Optical mouse
controlling mouse movement with feet
footmouse
small touch sensitive tablets
‘stroke’ to move mouse pointer
used mainly in laptop computers
Touchpad
lots of pixels per inch moved
initial movement to the target
fast stroke
less pixels per inch
for accurate positioning
slow stroke
- relative motion of the ball moves the cursor
- a ball held by a socket
trackball
- for accurate CAD - X-Y cursor
- for fast scrolling - single dial on mouse
thumbwheels
often used for computer games aircraft controls and 3D navigation
indirect - pressure == velocity
joystick
miniature joystick in the middle of the keyboard
keyboard nipple
detect the presence of finger
touch-sensitive screen
small pen-like pointer
stylus
- rarely use now
- uses light from screen to detect locality
light pen
mouse-like device with cross hairs
digitizing tablet
control interface by eye gaze direction
eye gaze
four keys ( ^ < > \/)
cursor keys
cursor pads/ mini joystick
discrete positioning controls
vast no. of collored dots/pixels in grid
bitmap display
set of colors
colormap
colors for each pallete
256 from a pallete
8 bits each for red, green and blue
colour dept
diagonal lines have discontinuitius
jaggies
soften edges by usng shades of line color
anti-aliasing
- stem for electrons emitted from electrogen
- used in tus and computer monitors
cathode ray tube
smaller, lighter and no radiation problem
found I nPDAs
liquid crystal displa
special displays
- dust
random scan
sim to random scan analouge
Directed View Storage Tube(DVST)
draw lines
random scan (directed beem refesh, vector display)
used for a meeting
large display
usually wide screen
plasma
lots of small screens together
video walls
RGB lights of LCD projector
- hand/body obscures screen
projected
frosted glass + projector behind
back-projected
display in public places
situated display
- thin flexible sheets that are updated electronically but retain display
digital paper
steering wheels, kno s and dials jus like real
cockpit and virtual controls
six-degrees movement: x(twist), y(up/down), z(left/right)
3d mouse
fibre optics used to dectect finger position
data glove
detect head motions
vr helmet
accelerometers strapped to limbs or replective dots and video processing
whole body tracking
use in sterescopic vison
- vr helmets
- screen plus shuttered specs
seeing ing 3d
- ordinary screen, mouse or keyboard control
- perspective and motion give 3d effect
desktop VR
small TV screen for each eye
- slightly different angles
VR headset
VR motion sickness
- time delay
depth perception
conflickting cues => sickness
dedicated displays
- analogue representations
- digital displays
- head-up displays
dials, gauges, lights
analogue representatons
small LCD screens, LED lights
digital displays
- found in aircraft cockpits
- show most important controls
head-up displays
- for controlling menus
- feel small bumps
BMW iDrive
image made from small dots
printing
use inked ribbon (80-120 dpi)
dot-matrix printer
blobs of ink (300+ dpi)
ink-jet and bubble-jet printer
uses powder toneer (600+ dpi)
laser printer
dpi stands for…
dots per inch
- dot matrix - cheques
- several paper rolls
shop tills
special heat-sensitive paper - fax machines
- poor quality but simple and low maintenance
thermal printer
the particular style of text
font
every character has the same width
fixed-pitch
some characters are wider
variable-pitch
square-ended strokes (helvetica)
sans-serif
with splayed ends (tlmes new roman/platino)
serif
easy to read shape of words
lowercase
better for individual letters and non-words
UPPERCASE
- helps your eye on long lines of printed text
- but sans serif often better on screen
serif fonts
most common page description languages
PostScript
WYSIWYG
what you see is what you get
take paper and convert it into a bitmap
scanner
types of scanner
- flat-bet
- hand-held
paper placed on a glass plate, whole page converted into bitmap
flat-bed scanner
scanner passed over paper, digitising strip typically 3-4” wide
hand-held scanner
Scanners is used in
- desktop publishing for incorporating photographs and other images
- document storage and retrieval systems, doing away with paper storage
- special scanners for slides and photographic negatives
converts bitmap back into text
- harder with different fonts
Optical Character Recognition (OCR)
small patterns of /\//\//\
glyphs
10 nano–second access time on silicon chips
- 100 MB/sec data transferred
Random Access Memory (RAM)
- floppy disks (1.4 mb)
had disks (40 gb to 100s)
magnetic disks
- use lasers to read and sometimes write
- more robust than magnetic media
optical disks
same technology as home audio = 600 gb
CD-ROM
for AV appliications or very large files
DVD
often use RAM for their main memory
PDAs (Personal Digital Assistant)
- used in PDAs, cameras
- silicon based
- plug-in USB devices for data transfer
flash-memory
recover exact text or image (GIF, ZIP)
look for commonalities
lossless
recover something like original (JPEG, MP3)
exploit perception
lossy
7-bit binary code = letter & character
- the basic standard for text storage
ASCII
8-bit encoding of 16 bit character set
- UNICODE standard
UTF-8
text plus formatting an glayout information
RTF (rich text format)
documents regarded as structured object
SGML (Standardized Generalised Markup Language)
simpler version of SGML for web applications
XML (Extended Markup Language)
- has quicktime, mpeg, wav formats
- compression even more important
- streaming formats for network delivery
audio/video
methods of access
indexing
- computers get faster and faster
- processor speed doubles = 18 m
- memory doubles = 12 months
Moore’s Law
computation takes ages, causing frustration for the user
computation bound
bottleneck in transference of data from disk to memory
storage channel bound
common bottlenect: updating displays = lots of effort
graphics bound
many computers networked, shared resources and files access to printers \/ network speed
network capacity
internet history
- 1969: darpanet us dod, 4 sites
- 1971: 23(arpanet)
- 1984: 1000
- 1989: 10000
common language protocols
TCP (Trasmission Control Protocol)
IP (Internet Protocol)
lower level, packets (like letters) between machines
TCP (Trasmission Control Protocol)
reliable channel (like a phone call) between programs on the machine
IP (Internet Protocol)
