Ch2_TheComputer.pdf

Imam Mohammad Ibn Saud Islamic University College of Computer and Information Sciences Computer Science Department CS351: Human Computer Interaction Chapter 2: The Computer Understanding computer hardware Inv...

Imam Mohammad Ibn Saud Islamic University College of Computer and Information Sciences Computer Science Department CS351: Human Computer Interaction Chapter 2: The Computer Understanding computer hardware Investigates how the technology influences the nature of the interaction and style of the interface. Instructor: Dr. Abeer Al-Nafjan  Human Computer Interaction Foundations Ch1: Human Ch2: Computer Ch3: Interaction the end-user of a the machine the program the user tells the computer program or others in the runs on what they want the organization computer communicates with results Input devices – text entry and pointing Output devices – screen, digital paper Virtual reality – special interaction and display devices Physical interaction – e.g. sound, haptic, bio-sensing Paper – as output (print) and input (scan) Memory – RAM & permanent media, capacity & access Processing – speed of processing, networks 2 The Computer In order to understand human–computer interaction, we need to understand computers! What goes in and out? devices, paper, sensors, etc. what can it do? memory, processing, networks 3 How many computers do you have!!? In your house? In your pockets? ▪ PC ▪ PDA ▪ TV, VCR, DVD, WiFi, ▪ phone, camera cable/satellite TV ▪ smart card, card with ▪ microwave, cooker, magnetic strip? washing machine ▪ electronic car key ▪ central heating ▪ USB memory ▪ security system 4 Interacting with computers Richer interaction – everywhere, every when ▪ rapid feedback ▪ the user in control (most of the time) ▪ doing rather than thinking … 5  The Computer- Devices Text-entry Devices Virtual Reality and 3D Devices ▪ Keyboards, phone pads, ▪ Positing and 3d space, moving number pads, handwriting, and grasping, seeing 3d speech recognition Special controls and Sensory Positing and Pointing Devices Devices ▪ Mouse, stylus, touch pad, ▪ Special displays, sounds, joysticks, touch screens, touch, feel, and smell, physical eyegaze controls, environmental and bio-sensing Display Devices Printing and Scanning Devices ▪ Bitmaps screens, large ▪ Printers, special printers, displays, situated displays scanners 6 Text-entry Devices Keyboards, the 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. Vast majority of keyboards have a standardized layout. – QWERTY – DVORAK 7 Text-entry Devices 8 Text-entry Devices Designs to reduce fatigue for RSI (Repetitive Strain Injury ) For one handed use e.g. the Maltron left-handed keyboard 9 Text-entry Devices Phone pad, use numeric keys with multiple presses 2–abc 6-mno 3-def 7-pqrs 4-ghi 8-tuv 5-jkl 9-wxyz hello = 4433555[pause]555666 surprisingly fast! 10 Text-entry Devices ATM number pad, it is numeric keypad for entering numbers quickly: – calculator, PC keyboard, telephones 7 8 9 4 5 6 1 2 3 0. = ATM Calculator 11 Text-entry Devices Handwriting recognition, text can be input into the computer, using a pen and a digesting tablet (natural interaction) Used in PDAs and tablet computers It face some technical problems: ▪ interpreting individual letters, styles of handwriting, and speed 12 Text-entry Devices Speech recognition is a promising area of text entry, 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 Speech technology has found niche markets: telephone information systems, access for the disabled. 13 Positioning and Pointing Devices Mouse; it is handheld pointing device. It is very common and easy to use. located on desktop ▪ Requires physical space ▪ No arm fatigue Two characteristics: ▪ Planar movement ▪ Buttons Two methods for detecting motion ▪ Mechanical ▪ Optical 14 Positioning and Pointing Devices 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 Joystick ▪ Often used for computer games aircraft controls and 3D navigation 15 Positioning and Pointing Devices Keyboard nipple; It miniature joystick in the middle of the keyboard for laptop computers Touch pad; small touch sensitive tablets used mainly in laptop computers 16 Positioning and Pointing Devices Touch screen; it is direct pointing device detect the presence of finger or stylus on the screen Advantages: fast, and good for menu selection Disadvantages: ▪ Finger can mark screen ▪ Imprecise; difficult to select small regions or perform accurate drawing 17 Positioning and Pointing Devices Eyegaze; control interface by eye gaze direction. It is potential for hands-free control ▪ e.g. look at a menu item to select it Uses laser beam reflected off retina ▪ High accuracy requires headset and expensive device ▪ Cheaper and lower accuracy devices available sit under the screen like a small webcam 18 Display Devices Bitmap screens; screen is vast number of coloured dots CRT used in TVs and computer monitors LCD used in PDAs, portables, notebooks, digital watches, mobile phones and increasingly on desktop and even for home TV Cathode Ray Tube (CRT) Liquid crystal displays (LCD) 19 Display Devices Large displays; used for meetings, lectures, etc. Technology: plasma – usually wide screen video walls – lots of small screens together Projected – RGB lights or LCD projector back-projected frosted glass + projector behind 20 Display Devices Situated displays; displays in ‘public’ places Two types: – Display only - for information relevant to location – Interactive- use stylus, touch sensitive screen Display only Interactive (info. only) (Kiosk.) 21  Example: Hermes a situated display Small displays beside office doors Handwritten notes left using stylus Office owner reads notes using web interface small displays beside office doors handwritten office owner notes left reads notes using stylus using web interface 22 VR and 3D Devices Positioning in 3D space: ▪ Data glove; fibre optics used to detect finger position ▪ VR helmets; detect head motion and possibly eye gaze ▪ Body tracking; accelerometers strapped to limbs or reflective dots and video processing Data glove Body tracking VR helmets 23 VR and 3D Devices Cockpit and virtual controls; steering wheels, knobs and dials … just like real! 3D mouse; six-degrees of movement: x, y, z + roll, pitch, yaw 24 VR and 3D Devices 3D Displays: ▪ Desktop VR Ordinary screen, mouse or keyboard control Perspective and motion give 3D effect ▪ Seeing in 3D Use stereoscopic vision VR helmets Screen plus shuttered specs, etc. 25 VR and 3D Devices Simulators and VR caves ▪ Scenes projected on walls ▪ Realistic environment ▪ Hydraulic rams! ▪ Real controls ▪ Other people 26 Special Controls and Sensory Devices Special displays (digital and heads up) 27 Special Controls and Sensory Devices Sound, touch, feel, and smell; senses such as touch and feel are important In games: vibration and force feedback In simulation: the feel of surgical instruments Haptic devices are devices that recreate the sense of touch by applying force, vibrations, or motion to the user 28 Special Controls and Sensory Devices Sound; Different types of sounds can be used, e.g. beeps, bongs, clonks, whistles and whirrs Used for error indication Confirmation of actions, e.g. keyclick 29 Special Controls and Sensory Devices Physical controls; specialist controls needed in: – industrial controls, consumer products, etc. 30 Special Controls and Sensory Devices Include environment and bio-sensing devices; Sensors all around us (environmental) ▪ Car courtesy light – small switch on door ▪ Ultrasound detectors – security ▪ RFID security tags in shops ▪ Temperature, weight, location … and even our own bodies (bio-sensing) ▪ Iris scanners, body temperature, heart rate, galvanic skin response, blink rate 31 Special Controls and Sensory Devices Environmental and bio-sensing 32 Special Controls and Sensory Devices Bio-sensing (wearable sensors) 33 Printing and Scanning Devices Printing in the workplace – Shop tills ▪ Dot matrix ▪ Same print head used for several paper rolls ▪ May also print cheques – Thermal printers ▪ Special heat-sensitive paper ▪ Paper heated by pins makes a dot ▪ Poor quality, but simple & low maintenance ▪ Used in some fax machines 34  Printing and Scanning Dot-matrix printers ▪ Use inked ribbon (like a typewriter ▪ Line of pins that can strike the ribbon, dotting the paper. ▪ Typical resolution 80-120 dpi Ink-jet and bubble-jet printers ▪ Tiny blobs of ink sent from print head to paper ▪ Typically 300 dpi or better. Laser printers ▪ Like photocopier: dots of electrostatic charge deposited on drum, which picks up toner (black powder form of ink) rolled onto paper which is then fixed with heat ▪ Typically 600 dpi or better. 35 Printing and Scanning Paper usually regarded as output only (printing) can be input too – OCR, scanning, etc. Scanner; used in desktop publishing for incorporating photographs and other images and document storage and retrieval systems. Flat-bed scanner Hand-held scanner (OCR) 36 Memory Short-term Memory – RAM; Random access memory (RAM) ▪ On silicon chips, 100 nano-second access time ▪ Usually volatile (lose information if power turned off) ▪ Data transferred at around 100 Mbytes/sec ▪ Typical desktop computers: 64 to 256 Mbytes RAM Long-term Memory - disks – Magnetic disks ▪ floppy disks store around 1.4 Mbytes ▪ hard disks typically 40 Gbytes to 100s of Gbytes, access time ~10ms, transfer rate 100kbytes/s 37 Memory – Optical disks ▪ Use lasers to read and sometimes write ▪ More robust that magnetic media ▪ CD-ROM - same technology as home audio, ~ 600 Gbytes ▪ DVD - for AV applications, or very large files – PDAs ▪ Often use RAM for their main memory – Flash-Memory ▪ Used in PDAs, cameras etc. ▪ Silicon based but persistent ▪ Plug-in USB devices for data transfer 38 Storage formats - media Some sizes (all uncompressed) … – This book, text only ~ 320,000 words, 2Mbytes – Scanned page ~ 128 Mbytes (11x8 inches, 1200 dpi, 8bit greyscale) – Digital photo ~ 10 Mbytes (2–4 mega pixels, 24 bit colour) – Video ~ 10 Mbytes per second (512x512, 12 bit colour, 25 frames per sec) Images: – Many storage formats : (PostScript, GIFF, JPEG, TIFF, PICT, etc.) – Plus different compression techniques (to reduce their storage requirements) Audio/Video – Again lots of formats : (QuickTime, MPEG, WAV, etc.) – Compression even more important – Also ‘streaming’ formats for network delivery Finite processing speed Designers tend to assume fast processors, and make interfaces more and more complicated But problems occur, because processing cannot keep up with all the tasks it needs to do – cursor overshooting because system has buffered keypresses – icon wars - user clicks on icon, nothing happens, clicks on another, then system responds and windows fly everywhere Also problems if system is too fast - e.g. help screens may scroll through text much too rapidly to be read Limitations on interactive performance Computation bound ▪ Computation takes ages, causing frustration for the user Storage channel bound ▪ Bottleneck in transference of data from disk to memory Graphics bound ▪ Common bottleneck: updating displays requires a lot of effort - sometimes helped by adding a graphics co-processor optimised to take on the burden Network capacity ▪ Many computers networked - shared resources and files, access to printers etc. - but interactive performance can be reduced by slow network speed Networked computing Networks allow access to … ▪ Large memory and processing ▪ Other people (groupware, email) ▪ Shared resources – esp. the web Issues ▪ Network delays – slow feedback ▪ Conflicts - many people update data ▪ Unpredictability HCI and memory, processing and networks How do you think new, fast, high-density memory devices and quick processors have influenced recent developments in HCI? Do they make systems any easier to use? Do they expand the range of applications of computer systems?