Key points HCI For Pen Based Computing UI Metrics Cont. Task - - PDF document
Key points HCI For Pen Based Computing UI Metrics Cont. Task completion time Accuracy Fluidity Richard Anderson Robustness CSE 481 B Feedback Winter 2007 Correctability Basic tasks Composite Tasks Targeting
UI Metrics
Task completion time Accuracy Fluidity Robustness Feedback Correctability
Targeting Tracing Mode indication
Selection Free form input Domain based input
Crossing
Operation triggered by a stroke crossing a
Specify operations
Principle – multiple commands without
Use movement through octants for
Item Text Shape Item Move Zoom Highlight Custom 400% 200% 100% 66.6% 50% 800% 25% Custom 400% 200% 100% 66.6% 50% 800% 25% 75.0 100.0
Enter text with specialized, stroke based
Optimized for automatic recognition Not human readable Character based or word based
Mostly single stroke Close to standard alphabet (learnability) Write only Location written for additional meaning
Identify one or more graphical elements
Mechanisms
Bounding Region Geometric defined by stroke Distance from cursor
Selection radius depends on object
UIs based on attaching meaning to ink
Gestures Diagram recognition Handwriting recognition
Free form Constrained recognition
Commands issued with a single stroke May be drawn or invisible Support from SDK
Register gestures to be recognized
UI Issues
Similar to keyboard short cuts
Speed up for experts Hard to learn / remember
Ambiguity
Distinction between gestures Distinction between gesture and other ink
Robustness
Handling misrecognized gestures
False positive False negative
Gesture initiated actions should be undoable
Challenges to recognition
Even simple shapes are hard! Variation in drawing Ink artifacts
We will have a great lecture later in the
Basic approach
Collect a huge amount of data Use data to train neural net
What level of error is tolerable How is feedback provided to the user
How does the user specify corrections?
Hands, obstructions, orientation
Hand blocks the
Accommodate left
Menu direction Context menus
Difficulties at the
Landscape vs. Portrait
Surprisingly big
Tablet PC requires rapid
Many standard desktop
Key points
Project scoping Technical Challenges being addressed Schedule and plans
Presentation Order
D, C, B, A
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