Chapter 24 Flashcards
PoHCI, week 2 (20 cards)
What is an input device?
A combination of hardware and software that allows users to transmit their intentions to a computer system.
What is a sensor?
A device that transforms physical energy into an electric signal
What is input sensing?
The whole sensing pipeline, including both software and hardware, that allows the computation of a
command based on sensor date
What does a traditional pointing device sense?
Motion, position or force
Name some sensing principles
Mechanical (position, motion, rotation)
Electrical (capicitance, contact)
Sonic (ultrasonic, microphone, sonar)
Optical (proximity, light, image)
Radiation (radar, heat, temperature)
Magnetic (hall effect)
Gravitational (LIGO)
What is an analog and digital sensor?
Analog: Output an analog electrical signal, typically between 0 and 5 V converted by an ADC
Digital: Output a digital signal: zeros and ones, converted by a digital protocol (UART, I2C, SPI).
What is a transfer function?
A function that maps a change in input energy to a change in electric signal (output energy)
What is bias level and noise?
Bias level: A systematic source of error in transfer
Noise: Unsystematic (quasi-random) error
What is the sensing modality?
The sensing modality of input refers to the particular input stream considered, such as speech, hand
movement, pen movement, handwriting, gaze etc.
Can be multimodal (multiple input streams are combined)
What is the temporal resolution?
The temporal resolution of an input device is its discrete resolution of the measurement of time
Example (mouse): High temporal resolution means many samples of mouse movements are captured by the input device at a fixed unit of time
What is the spatial resolution?
The spatial resolution of an input device is its discrete resolution of measurement in the spatial
domain.
Example: A hand-tracking input device may be able to track a user’s hand with a resolution of 5 mm
What is accuracy?
Accuracy reflects the ability of an input device to correctly sense the user’s input
What is a directly- and indirectly controlled pointing device?
A directly controlled pointing device is interacted with by pointing directly at the display.
An indirectly controlled pointing device allows the user to specify a location on display by manipulating
the pointing device.
What is direct control?
Direct control pointing devices allow the user to select an absolute coordinate on a display
Name some direct control input devices
Light pen
Resistive touchscreen
Capacitive touchscreen
What is indirect control?
Indirect control pointing devices enable the user to control a cursor on a display in response to manipulation of the pointing device
Name some indirect control input devices
Mouse
Touchpad
What is uncertain control?
Uncertain control refers to a class of input devices that must be designed to be robust in the presence
of significant uncertainty around the user’s intention
Name some uncertain control devices
Switch (mechanical push button)
Accelerometers and Gyroscopes
Brain-Computer Interface
Electromyography
Eye tracking
Hand- and finger tracking
Explain adaptation
The ability to change the user interface based on sensed information about the current state of the users, for instance, their workload
