Input Devices and Theory Input for Selection and
- Slides: 34
Input: Devices and Theory
Input for Selection and Positioning n n n Devices Power Law of Practice Fitt’s Law (2 D, 3 D lag) Eye hand coordination Two handed Methods and Metaphors
5 Virtual Devices. Adapted from Wallace, 1976. "The Semantics of Graphic Input Devices" n n n Button - Indicates Choice (binary) - radio buttons are an extension of this concept. Keyboard - Alpha numeric strings - a lot of buttons (voice) Pick Device - For selection of graphic objects The canonical example of this is a light pen. Locator - For specifying screen coords - x, y position(e. g. mouse) Valuator - generating floating point values: A potentiometer.
Power Law of Practice n Time to perform a task is proportional to the log of the number of times the task has been carried out. log(Tn) = log(T 1) - a. log(n) n The law is usually expressed in terms of blocks of trials since the time to perform a single trial is too variable.
Law of Diminishing Returns Applicable to Choice reaction Typing Many skilled behaviors
Fitt’s Law for position selection n Mean. Time = C 1 + C 2 log 2(D/W + 0. 5) (1) Mean. Time = C 1 + C 2 log 2(D/W + 1. 0) (2) n Index of difficulty = log 2(D/W + 1. 0) n Index of performance = 1/C 2 About 5 -8 bits per second (many devices) n n
Modified Fitt’s Law n Mean. Time = C 1 + C 2(Human + Machine)ID
Control loop
Fish Tank VR (is head pos important) is stereo important. Ar Arsenault and Ware (2001) TOCHI
Effects of incorrect perspective
Task: Tapping from target to target
Effects of stereo in eye hand coordination Approx 3 bits per second (best case)
Effects of correct perspective (HT) Index of Performance Summary No Stereo No HT 1. 58 2. 41 HT 1. 75 2. 70 In bits per second
Factors in input device design n n Degrees of Freedom Order of control (Milgram) p = a + bt + ct 2 n n Mappings between devices and tasks n n n Position (0) Velocity (1) Acceleration (2) S-R compatibility Integral/separable Isometric/compliant
Direct Manipulation n n Visibility of objects and actions Rapid reversability < 100 msec lag in visual feedback Users n n n Feelings of mastery and control Ease of learning Perceived Transparency “The user is able to apply intellect directly to the task; the tool itself seems to disappear”. (Rutowsky, 1982)
3 D Rotations with a 2 D interface n n Virtual Trackball (Chen, 17. 5 seconds, Hickley 26 sec. ) Arcball 26 seconds (Hinckely, 1997 Shoemake 1992)
Rotations 3 dof n n n Ware: 55 seconds accuracy, 14 seconds speed Hinckley 3 ball 20. 7 f sec 14 m sec Zhai 18 sec. Wang: real object rotations of 45 deg in less than a second Ware and Rose: real object rotation < 2 sec virtual objects, real handles
Handles Real and Virtual Ware and Rose
Real Object Rotations n Hand in the same place as an object helps
Where, between real and virtual does performance break down? Monitor Mirror
Ware and Rose: results n n n Hand in the same place as an object helps (30 %). Random end harder than random start. Sphere vs shape match is a minor factor
Experiment n Two objects: n n Wire-frame, color coded tetrahedron Solid shape
Results Color result confirms Hypothesis No major difference In efficiency
Radical solutions n n Gadget methods Screen space methods
Props: Physical Objects that Support Interaction (Hinckley)
Guiard’s Kinematic Chain Theory n n The left and right hands make up a functional kinematic chain: for right-handers, the right hand moves relative to the output of the left hand. General principles: 1. Right-to-left reference: The right hand performs its motion relative to the frame of reference set by the left hand. 2. Asymmetric scales: Different temporal-spatial scales of motion. 3. Left hand precedence: The left hand precedes the right: for example, the left hand first positions the paper, then the right hand begins to write.
Two Handed Interaction n Props Toolglasses and magic lenses Tool use, e. g. rulers and guides
Gestures
n n Gestures can speed up input Can be iconic Sketch beautification Erase, create objects, etc.
Dynamic Querie (Schneiderman) n Interactively expose an hide multidimensional discrete data. n One slider per data dimension.
Frames of Reference n n n Retinocentric (2 df) look at something Head centered (2 df) pan and tilt Torso centered (2 df) turn move forward Hand centered (6 df) object orientation Exocentric: Object centered point direction, intersection, docking, ROV control
- Input devices
- Two way selection and multiway selection in c
- Multiway selection in c
- Mass selection
- Balancing selection vs stabilizing selection
- Similarities
- K selection r selection
- Natural selection vs artificial selection
- Difference between continuous and discontinuous variation
- Example of sexual selection
- Logistic model of population growth
- Natural selection vs artificial selection
- Automatic input devices
- Graphics monitors and workstations in computer graphics
- Literary technique
- Fspos
- Typiska drag för en novell
- Tack för att ni lyssnade bild
- Vad står k.r.å.k.a.n för
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