Chapter 6 Direct Manipulation and Virtual Environment




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Chapter 6

Direct Manipulation and Virtual Environment



6.1 Introduction


  • Positive feelings associated with good user interfaces:

    • Mastery of the interface

    • Competence in performing tasks

    • Ease in learning the system originally and in assimilating advanced features

    • Confidence in the capacity to retain mastery over time

    • Enjoyment in using the system

    • Eagerness to show the system off to novices

    • Desire to explore more powerful aspects of the system


6.2 Examples of Direct-Manipulation Systems
6.2.1 Command line vs. display editors and word processors

  • Training times with display editors are much less than line editors

  • Line editors are generally more flexible and powerful

  • The advances of WYSIWYG word processors:

    • Display a full page of text

    • Display of the document in the form that it will appear when the final printing is done

    • Show cursor action

    • Control cursor motion through physically obvious and intuitively natural means

    • Use of labeled icon for actions

    • Display of the results of an action immediately

    • Provide rapid response and display

    • Offer easily reversible actions


Technologies that derive from the word processor:

  • Integration

  • Desktop publication software

  • Slide-presentation software

  • Hypermedia environments

  • Improved macro facilities

  • Spell checker and thesaurus

  • Grammar checkers


6.2.2 The VisiCalc spreadsheet and its descendants

  • VisiCalc users delighted in watching the program propagate changes across the screen.

  • In some cases, spatial representations provide a better model of reality

  • Successful spatial data-management systems depend on choosing appropriate:

    • Icons

    • Graphical representations

    • Natural and comprehensible data layouts



6.2.4 Video games

  • From PONG to Nintendo GameCube, Sony PlayStation 2, and Microsoft Xbox

  • Field of action is visual and compelling

  • Commands are physical actions whose results are immediately shown on the screen

  • No syntax to remember

  • Most games continuously display a score

  • Direct manipulation in SimSity

  • Myst well received

  • DOOM and Quake controversial


6.2.5 Computer-aided design

  • Computer-aided design (CAD) use direct manipulation

  • Manipulate the object of interest

  • Generate alternatives easily

  • Explain the impact

  • Problem solving by analogy to the real-world

6.2.6 Office automation

  • Xerox Star was a pioneer with sophisticated formatting

  • Apple Lisa System

  • Rapid and continuous graphical interaction

  • Microsoft Windows is a descendant


6.3.2 The OAI Model explanation of direct manipulation

  • Portrait of direct manipulation:

    • Continuous representation of the objects and actions of interest

    • Physical actions or presses of labeled buttons instead of complex syntax

    • Rapid incremental reversible operations whose effect on the object of interest is immediately visible




  • Beneficial attributes:

    • Novices learn quickly

    • Experts work rapidly

    • Intermittent users can retain concepts

    • Error messages are rarely needed

    • Users see if their actions are furthering their goals

    • Users experience less anxiety

    • Users gain confidence and mastery




6.3.3 Visual Thinking and Icons


  • The visual nature of computers can challenge the first generation of hackers

  • An icon is an image, picture, or symbol representing a concept

  • Icon-specific guidelines

    • Represent the object or action in a familiar manner

    • Limit the number of different icons

    • Make icons stand out from the background

    • Consider three-dimensional icons

    • Ensure a selected icon is visible from unselected icons

    • Design the movement animation

    • Add detailed information

    • Explore combinations of icons to create new objects or actions


Five levels of icon design:

    • Lexical qualities. Machine-generated marks—pixel shape, color brightness, blinking

    • Syntactics. Appearance and movement—lines, patterns, modular parts, size, shape

    • Semantics. Objects represented—concrete versus abstract, part versus whole

    • Pragmatics. Overall legibility, utility, identifiability, memorability, pleasingness

    • Dynamics. Receptivity to clicks—highlighting, dragging, combining


6.4 3D Interfaces


  • “Pure” 3D interfaces have strong utility in some contexts, e.g., medical, product design. In other situations, more constrained interaction may actually be preferable to simplify interactions.




  • “Enhanced” interfaces, better than reality, can help reduce the limitations of the real-world, e.g., providing simultaneous views.




  • Avatars in multiplayer 3-D worlds,

      • e.g., ActiveWorlds






Features for effective 3D

    • Use occlusion, shadows, perspective, and other 3D techniques carefully.

    • Minimize the number of navigation steps for users to accomplish their tasks.

    • Keep text readable.

    • Avoid unnecessary visual clutter, distraction, contrast shifts, and reflections.

    • Simplify user movement.

    • Prevent errors.

    • Simplify object movement

    • Organize groups of items in aligned structures to allow rapid visual search.

    • Enable users to construct visual groups to support spatial recall.


Guidelines for inclusion of enhanced 3D features:

    • Provide overviews so users can see the big picture

    • Allow teleportation

    • Offer X-ray vision so users can see into or beyond objects.

    • Provide history keeping

    • Permit rich user actions on objects

    • Enable remote collaboration

    • Give users control over explanatory text and let users select for details on demand.

    • Offer tools to select, mark, and measure.

    • Implement dynamic queries to rapidly filter out unneeded items.

    • Support semantic zooming and movement

    • Enable landmarks to show themselves even at a distance

    • Allow multiple coordinated views

    • Develop novel 3D icons to represent concepts that are more recognizable and memorable.

6.5 Teleoperation


  • Two “parents”: direct manipulation in personal computers and process control in complex environments

  • Physical operation is remote

  • Complicating factors in the architecture of remote environments:

    • Time delays

      • transmission delays

      • operation delays

    • Incomplete feedback

    • Feedback from multiple sources

    • Unanticipated interferences


6.6 Virtual and Augmented Reality


  • Virtual reality breaks the physical limitations of space and allow users to act as though they were somewhere else

  • Augmented reality shows the real world with an overlay of additional overlay

  • Situational awareness shows information about the real world that surrounds you by tracking your movements in a computer model

  • Augmented reality is an important variant

  • Enables users to see the real world with an overlay of additional interaction.

  • Successful virtual environments depend on the smooth integration of:

    • Visual Display

    • Head position sensing

    • Hand-position sensing

    • Force feedback

    • Sound input and output

    • Other sensations

    • Cooperative and competitive virtual reality


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