Direct Manipulation and Virtual Environments

Direct Manipulation and Virtual Environments

A. 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 

B. Examples of Direct-Manipulation systems

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 

The VISICALC spreadsheet and its descendants Spatial data management

• 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 

Video games 

• Field of action is visual and compelling
• Commands are physical actions whose results are immediately shown on the screen
• No syntax to remember
• Computer-aided design Office automation Further examples of direct manipulation
• HyperCard
• Quicken 

C. Explanations of Direct Manipulation

Problems with direct manipulation 

• Spatial or visual representations can be too spread out
• High-level flowcharts and database-schema can become confusing
• Designs may force valuable information off of the screen
• Users must learn the graphical representations
• The visual representation may be misleading
• Typing commands with the keyboard my be faster
• 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 

D. 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 
• Syntactics
• Semantics
• Pragmatics
• Dynamics 

E. Direct-Manipulation Programming

Visual representations of information make direct-manipulation programming possible in other domains.

Demonstrational programming is when users create macros by simply doing their tasks 

The five challenges of programming in the user interface: 

• Sufficient computational generality
• Access to the appropriate data structures and operators
• Ease in programming and editing programs
• Simplicity in invocation and assignment of arguments
• Low risk 

Cognitive dimensions framework may help analyzing design issues of visual programming environments.

F. Home Automation

Remote control of devices is being extended to: 

• Channel audio and video
• Lawn watering
• Video surveillance and burglar alarms
• Multiple-zone environmental controls
• Maintenance records 

Providing direct-manipulation with rich feedback is vital in these applications 

Many direct-manipulation actions take place on a display of the floor plan 

ON and OFF can have many representations and present problems with choosing the appropriate one Controlling complex home equipment by direct manipulation reshapes how we think of homes and residents.

G. Remote Direct Manipulation

Complicating factors in the architecture of remote environments: 

• Time delays :

• transmission delays

• Operation delays 

• Incomplete feedback
• Feedback from multiple sources
• Unanticipated interferences 

H. Virtual Environments

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 

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