Transcript Overview and Detail - Visual Analytics Digital Library

Overview and Detail
CS 7450 - Information Visualization
February 10, 2005
John Stasko
Fundamental Problem
• Scale - Many data sets are too large to
visualize on one screen
 May simply be too many cases
 May be too many variables
 May only be able to highlight particular cases
or particular variables, but viewer’s focus may
change from time to time
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Overview
• Providing an overview of the data set can
be extremely valuable
 Helps present overall patterns
 Assists user with navigation and search
 Orients activities
• Generally start with overview
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Details
• Viewers also will want to examine details,
individual cases and variables
• How to allow user to find and focus on
details of interest?
• Generally provide details on demand
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Providing Both
• Overview + detail displays can be
combined via either time or space
 Time - Alternate between overview and
details sequentially in same place
 Space - Use different portions of screen to
show overview and details
• Each has advantages and problems
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Specific Problem
• Develop visualization and interface
techniques to show viewers both overview
+ detail, and allow flexible alternation
between each
• Potential Solutions????
 Discuss….
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Common Solution
• Scroll
 Provide a larger, virtual screen by allowing
user to move to different areas
• Still a problem
 Clunky interaction
 Only get to see one piece
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Worthy Objective
• Allow viewer to examine cases and/or
variables in detail while still maintaining
context of those details in the larger
whole
• Concession
 You simply can’t show everything at once
• Be flexible, facilitate a variety of user
tasks
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Nature of Solutions
• Not just clever visualizations
• Navigation & interaction just as important
• Information visualization & navigation
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Confound
Devices with even smaller screens are becoming more popular!
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An Example
Detail-only view (from Civilization II game)
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An Example
overview
detail
Overview and detail (from Civilization II game)
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Plaisant et al Article
• Good introduction to overview/detail issue
• Application concern: viewing and editing
large images
• Expanding the notion of the one
dimensional scroll bar: zooming, diagonal
panning, multiple detailed views
• List of visualization/interaction solutions
IEEE Software ‘95
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1. Detail-only
• Single window with
horizontal and vertical
panning
• Works only when zoom
factor is relatively small
• Example: Windows
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2. Single window with zoom and
replace
• Global view with
selectable zoom area
which then becomes
entire view
• Variations can let users
pan and adjust zoomed
area and adjust levels of
magnification
• Context switch can be
disorienting
• Example: CAD/CAM
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3. Single coordinated pair
• Combined display of the
overview and local
magnified view (separate
views)
• Some implementations
reserve large space for
overview; others for
detail
• Issue: How big are
different views and where
do they go?
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4. Tiled multilevel browser
• Combined global,
intermediate, and
detail views
• Views do not overlap
• Good
implementations
closely relate the
views, allowing
panning in one view
to affect others
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5. Free zoom and multiple overlap
• Overview presented
first; user selects area
to zoom and area in
which to create
detailed view
• Flexible layout, but
users must perform
manual window
management
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6. Bifocal magnified
• “Magnifying glass”
zoomed image floats
over overview image
• Neighboring objects
are obscured by the
zoomed window
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7. Fish-eye view
• Magnified image is
distorted so that focus is
at high magnification,
periphery at low
• All in one view
• Distortion can be
disorienting
• More details next class...
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Remain Task-Driven
The goal is to identify the primary type of
task the user will be performing and adapt
the browser to best fit the needs of that
user
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Task Taxonomy
• Image generation: overview is important, but
most of time is spent at detail level
 Example: CAD/CAM
• Open-ended exploration: overview not always
complete; navigation must be fluent and easily
mastered
 Example: Interactive Map
• Diagnostic: high detail, fluent panning and
complete image coverage
 Example: Circuitry Design
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Task Taxonomy
• Navigation: global view with increased
magnification detail areas; panning and
zooming less important
 Example: Geographic Information System
• Monitoring: Global view with multiple
detailed views for local troubleshooting;
window management is critical
 Example: Network management
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Browser Taxonomy
• Once the user task has been determined,
a browser appropriate to that task can be
identified
• Plaisant suggests a browser taxonomy to
classify and group browsers with similar
features
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Browser Taxonomy
• Static Presentation Browsers
 Single View
Detail-only
Zoom-and-replace
Fish-eye
Superimposition
 Multiple View
Window-placement strategy
Ratio of sizes
Coordination (none / unidirectional / bidirectional)
Global view
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Browser Taxonomy
• Dynamic Presentation Browsers
 Quality of the Update
 Nature of the Update (“Level of Detail”)
 Zooming Factor
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Additions/Variations
• Since the writing of the article, new
techniques and many variations have
been developed...
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Magnifier Problem Fix
DragMag Image Magnifier
hello
More text
hello
Video
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Bifocal magnified
display without
problem of
obscuring the
neighboring items
Ware and Lewis
CHI ‘95
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Transparent Overlays
Make detailed view semi-transparent, then overlay overview
with it
May even control transparency of each
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UIST ‘94
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Important Issue
• The “overview” display may need to
present huge number of data elements
• What if there simply isn’t enough room?
 The number of data elements is larger than
the number of pixels
• Approaches?
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Two Main Approaches
• 1. Interactive display (add scrolling)
 Is it still an overview?
• 2. Reduce the data
 Eliminate data elements
But then is it still an overview?
 Aggregate data elements
• 3. Reduce the visual representation
 Smart ways to draw large numbers of data
elements
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Drawing the Overview
Information Mural
What do you do when your data set is too large for
your overview window?
--- More data points than pixels
--- Don’t want to fall back on scrolling
Jerding and Stasko
InfoVis ‘95, IEEE ToVCG ’98
www.cc.gatech.edu/gvu/softviz/infoviz/information_mural.html
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Information Mural
Use techniques of computer graphics (shading and
antialiasing) to more carefully draw overview displays
of large data sets
Think of each data point as ink and each screen pixel
as a bin
Data points (ink) don’t fit cleanly into one bin, some
ink may go into neighboring bins
Can map density to gray or color scale
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Mural Algorithm
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Mural Example
Object-oriented code executions
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Mural Example
Sunspot activity over 150 years
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Mural Example
normal
Parallel
Coordinates
muralized
colorized
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Mural Example
Message passing in parallel program
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Mural Example
U.S. Census Data
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Mural Example
LaTeX
source
file
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Multiple Windows/Views
• Fundamentally, (good) overview & detail
involves multiple views
• When should you use multiple views?
• What makes a good multiple view system?
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Design Guidance
• Nice paper with many design guidelines
• Model of multiple view system
 1. Selection of views
 2. Presentation of views
 3. Interaction among views
Wang Baldonado, Woodruff, and Kuchinsky
AVI 2000
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When to Use Mult. Views
• Diversity - Use m.v. when there is a diversity
of attributes, models, user profiles, levels of
abstraction or genres
• Complementarity - Use m.v. when different
views bring out correlations and/or disparities
• Decomposition - Partition complex data into
m.v. to create manageable chunks and to
provide insight into the interaction among
different dimensions
• Parsimony - Use m.v. minimally
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How to Use Multiple Views
• Space/Time Resource Optimization - Balance the
spatial and temporal costs of presenting m.v. with the
spatial and temporal benefits of using the views
• Self Evidence - Use perceptual cues to make
relationships among m.v. more apparent to the user
• Consistency - Make interfaces for m.v. consistent, and
make the states of m.v. consistent
• Attention Management - Use perceptual cues to
focus the user’s attention on the right view at the right
time
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Still to come...
• Related topics coming up:
 Focus + Context views
Typically one display window or view for both
overview and detail that uses some form of
distortion to combine them
 Panning and zooming
More detailed study of interaction techniques to
support overview and detail displays
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HW4
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Questions?
Due Tuesday
Submit 2 hardcopies in class
Email pdf of report to eaganj@cc
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Final Project
• Contest data set
• Advertising of topics & teams
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Upcoming
• Tools discussion & design session
• Time series data
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References
• Spence and CMS books
• All referred to articles
• S. Meier, Civilization II. MicroProse:1998
http://www.civ2.com
• Demonstration maps generated at
MapQuest, http://www.mapquest.com
• F’99 slides from Voida, Zhang, Zook and
Stenger
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