Flashcards
SCC 202 - Input and Output
Cards in this deck (24)
- 1List different sensing methods and give examples?mechanical- (e.g., switch, potentiometer) motion- (e.g., accelerometer, gyroscope) contact (e.g., capacitive touch, pressure sensor)
signal processing (e.g., computer vision, audio) - 2Why was qwerty keyboard designed?QWERTY is designed to space “typebars” to reduce jams and speed typing up, and not designed to slow typists down.
- 3State another keyboard layout apart from qwerty?Dvorak keyboard layout?
- 4List some Dvorak corrections to keyboard layout? Include explanation of hand alternation, improving speed and efficiency and the least common letters?Letters should be typed by alternating between hands.
For maximum speed and efficiency, the most common letters and digraphs should be the easiest to type. Thus, about 70% of keyboard strokes are on home row.
The least common letters should be on the bottom row, which is the hardest row to reach.
The right hand should do more of the typing, because most
people are right-handed. - 5Why are keyboards frequently downsized?To increase portability of devices, keyboards are frequently downsized:
Low-profile keys, smaller keys.
All interfere with typing.
Much more significant a problem than Dvorak vs Qwerty keyboards - 6Effects of soft/ virtual keyboards? Relation to ergonomicMany ergonomic problems: feedback, resting of hands significantly compromised.
However, increases the aesthetics of device by reducing thickness, overall size, and weight.
Good option when input can be significantly limited but bad if device requires text input. - 7Describe Graffiti/Uni stroke gestures and Natural handwriting recognition? Map single strokes to “enter letter” commands
Dictionary-based classification algorithms - 8Define position input?Control the position of a pointer or input area on-screen.
- 9Relating to mouse, joysticks, Expand on Force vs Displacment and Postion vs Rate control. Force vs. Displacement Sensing (most) joysticks = force; mouse = displacement
Position vs. Rate Control (most) joysticks = rate; mouse = position - 10Relating to mouse and touchscreen, expand on Absolute vs Relative positioning and Direct vs indirect contact?Absolute vs. Relative Positioning touchscreen = absolute; mouse = relative
Direct vs. Indirect Contact direct = touchscreen; indirect = mouse - 11Define force vs displacement sensing?Also called “isometric” (force) versus “isotonic” (displacement) sensing.
Elastic isometric devices: as we apply a force an opposing force develops that returns the input control to it neutral position. - 12Define position vs rate control transfer function?Force sensing (isometric) should be mapped to rate.
Displacement (isotonic) sensing should be mapped to position - 13Define absolute and relative position?Absolute position is a direct mapping of input device position to a display input position.
Relative position maps changes in input device position to changes in display input position. - 14Define control display gain?Can add a scale factor when mapping the input device (the ‘control’) to the display.
A ratio of display movement to control movement called ‘gain’, often in terms of input device velocity (so works with rate and position controls): - 15Formula for CD gain in relation to pointer and device?CDgain = Vpointer/ Vdevice
- 16What might we want to sense when interacting with touchless interfaces and describe them?Occupancy & Motion: senses motion or a person’s presence.
Range: calculate distance to a given object.
Position: Geo-location of the device.
Movement and Orientation: sense spatial motion (e.g., translation, rotation).
Gaze: determining where a person is looking (e.g. determining target on-screen)
Speech: detect and process voice input or commands (e.g. Siri)
Brain-wave activity: low-fidelity input, potential for accessibility. - 17What might we do with information collected from touch less interfaces?Support In-Air Gestures: hand pose, spatial trajectory of hands or stylus
Identify objects or people: object recognition, person recognition (face recognition)
Determine context: figure out the context of the user (e.g. in-car)
Determine Affect: detect an emotion or subjective feeling in a person - 18Challenges with touch less interfaces?May require data from multiple sensors. Sensor data is noisy.
Computer vision is computationally expensive.
Integration into real world applications.
Balancing explicit interaction (e.g. Siri, kinect) and implicit interaction (e.g. smart homes, personalized services). - 19Expand on False positive and negative Errors with touch less interfaces?- False Positive Error
User does not intend to perform a gesture but the system recognizes one.
Makes the system seem erratic or overly sensitive.
- False Negative Error:
User believes he/she has performed a gesture but the system does not recognize it
Makes system seem unresponsive, like the user is doing something wrong. - 20Expand on Balance and strategies error with touch less interfaces?Need to Balance:
Users need to feel a sense of control
Should be able to correct mistakes and make explicit control in exceptional cases (e.g. many people in front of a gesture system) Users may be intolerant of errors
Strategies:
Graceful degradation: return similar or ‘close’ results.
Avoid false positives by seeking confirmation from the user.
Give control: allow users to query the system for why it took a given action, fix errors, and revert to manual mode. - 21key challenge of in air gestures touch less interfaces?Key challenge: in-air gesture system is always on, and there is no mechanism
that will differentiate gestures from non-gestures. - 22How can reserved actions help combat in air gestures problems? Take a particular set of gestural actions and reserve them so that those actions are always used for navigation or commands.
- 23How can reserving a clutch help combat in air gestures errors?A gestural clutch is an indicator that you want to start or stop the recognition of a gesture.
Example: to engage, user pushes past an invisible plane in front.
Advantages: The gesture recognizer knows that the following action is a command gesture; allows the complete ‘gesture space’ to be used.
Disadvantages: Where/what should the clutch be? Still have to recognize it! - 24How can Multi modal input combat in air gestures errors state advantages and disadvantages?The multi-modal solution enables touch input to be sent to the application, while hardware buttons control universal parameters (e.g., volume) and navigation (e.g., go home).
Advantages: does not reduce the vocabulary of the primary gestural modality (by reserving one action as a ‘clutch’.
Disadvantages: requires and additional input device or modality.
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- Flashcards on SCC 202 - Input and Output, created by Ayo Olutobi on 18/03/2017.
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- Ayo Olutobi
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