Cheops: A Compact Explorer for Complex Hierarchies

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Giza A framework for visualization
Louis C. Vroomen, Marc-Antoine Parent Luc
Beaudoin
Human Computer Interaction Group Centre de
recherche informatique de Montréal http//www.crim
.ca/ipsi (Français) http//www.crim.ca/hci
(English)
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Outline of presentation
Problem definition CHEOPS approach Giza
Framework Inside Giza Context How to reach us
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Outline of presentation
Problem definition CHEOPS approach Giza
Framework Inside Giza Context How to reach us
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Problem definition
Components of a Traditional Visualization Approach
Visualization
Command
Data modeling
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Problem definition
Framework

• Set of cooperating classes
• reusable designs for a specific class of software
• customize to a particular application by creating
  application-specific subclasses of classes from
  the framework
• Visualization
• set of classes to facilitate the creation of a
  flexible visualization application

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Problem definition
Components of a Visualization Framework
Task
Visualization
Data modeling
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Problem definition
Main task

• Navigation
• provide flexible means to access elements and the
  relations between them.
• user can perform two types of actions
• structural analysis
• investigation

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Problem definition
Actions

• Structural analysis
• support visual correlation and discrimination
  tasks by providing the ability to compare,
  simultaneously, remote parts of a structure.
• Investigation
• reinforce the expression of the current location,
  in context if possible, and refine the control
• where have I been, where am I, where can I go.

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Outline of presentation
Problem definition CHEOPS approach Giza
Framework Inside Giza Context How to reach us
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CHEOPS approach
Purpose

• Ability to browse and explore complex
  hierarchical information structures,
• Ease of use,
• Runs on standard personal computers, with SVGA
  resolution.

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CHEOPS approach
Dewey Decimal Classification System

• 10 by 10 levels deep, with 1.2 cm triangles,
  drawn out would take 12,000 km.
• CHEOPS fits within 12 cm. square

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CHEOPS approach
Design

• Object-oriented design
• versatile,
• scalable.
• Written in JavaTM
• cross-platform,
• usable over the net.

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CHEOPS approach
Some advantages (1/3)

• Small foot print for fairly deep hierarchies
• Reuse of few visual objects
• allows display of large hierarchies ,
• quick update on a personal computer.
• Processing the opening of a branch is a fast,
  simple descent

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CHEOPS approach
Some advantages (2/3)

• CHEOPS provides a stable,
  synthetic view of the global structure
• The relationship between
  global context and the selected branch
  is always
  maintained.
• At each node, CHEOPS providesa unique and
  permanent visual signature
• visual signatures facilitate re-entry,
• representation of deep descendants allows long
  jump.

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CHEOPS approach
Some advantages (3/3)

• Strategies are consistent
  everywhere in the hierarchy andthey enhance one
  another
• users can combine available tools to form
  strategies to fit their needs,
• this ability allows users an incremental,
  yet quick method to learn the approach
  and optimize their strategies.

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CHEOPS approach
General difficulties / possible solutions

• Branching factor
• investigate new manipulation tools
• Very deep hierarchies
• fragmentation strategies (eg relative root
  position)
• As hierarchies grow, descent can become
  computationally intensive
• load on demand?

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CHEOPS approach
Limitations inherent to CHEOPS / possible
solutions

• One branch open at a time
• different visual semantics
• investigate complementary manipulation tools
• People are disconcerted by speed power
• learning curve seems quite short

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CHEOPS approach
Implementation limitations / possible solutions

• Need all nodes in memory to descend and for ghost
• load on demand with limited ghost information
• Overloading is arbitrary
• investigate placement by a simple ordering
  function

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CHEOPS Approach
Next step

• Investigate identified solutions
• Representation of non-hierarchical links
• Representation of graphs
• Access tools like histograms and filters

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Outline of presentation
Problem definition CHEOPS approach Giza
Framework Inside Giza Context How to reach us
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Giza Framework
Limitations of first Cheops implementation (1/3)

• Data model and visualization coupling
• inherently hierarchical, thus cannot show
  non-hierarchical relations or graphs

Task
Visualization
Data modeling
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Giza Framework
Limitations of first Cheops implementation (2/3)

• Visualization and task coupling
• Cheops only one representation, yet different
  representations may be required
• need to visualize associated data, filtering

Task
Visualization
Data modeling
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Giza Framework
Limitations of first Cheops implementation (3/3)

• Data modeling and task coupling
• inherently hierarchical browsing

Task
Visualization
Data modeling
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Giza Framework
Giza Framework

• Object oriented framework
• Plugable representations
• now cheops, millipede, tree, explorer
• soon fish-eye, intelligent zoom,
  hyperbolic geometry, tree map,etc.
• Extendable widgets
• investigate new manipulation tools
• Customizable

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Giza Framework
Results

• Redesign of architecture
• Attempt decoupling data modeling/visualization
• can visualize non-hierarchical links.
• multiple representations available and easy to
  implement
• Attempt decoupling task/visualization
• representations can be notified of state changes
• associated data viewable (timelines, etc.)
• filtering available based on data model

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Giza Framework
Results

• Attempt decoupling data model from task
• Can navigate through non-hierarchical links and
  graphs

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Outline of presentation
Problem definition CHEOPS approach Giza
Framework Inside Giza Context How to reach us
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Inside Giza Context
Analysing the modeling approach

• What is in the model for structures(hierarchies
  and graphs)?
• Elements with properties
• Links define a structure (a topology)

Data Modeling
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Inside Giza Context
Analysing the visualization technique

• What is in a representation?
• Components with visual attributes
• The layout of components defines neighbourhood
  (topology)

Visualization
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Inside Giza Context
Analysing the visualization technique (1/2)

• Traditional approach (MVC) components and
  elements within a representation correspond 1 to
  1

Data Modeling
Visualization
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Inside Giza Context
Analysing the visualization technique (2/2)

• Cheops Many elements displayed by one component
• Multiple representations, polymorphy Many
  components display some elements

Data Modeling
Visualization
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Inside Giza Context
Abstract coupling of properties

• Decoupling visualization from data
• Access properties through an abstract protocol
• Representing arbitrary structures
• Make topology into a property

Visualization
Data Modeling
Abstract
protocol
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Inside Giza Context
Recipes for coupling of properties

• Encapsulate coupling to vary it
• Each coupling is made into an accessor object
• Multiple representations
• Each representation couples its attributes to
  properties through a distinctive process

Data Modeling
Visualization
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Inside Giza Context
Contexts to bring accessors together

• The couplings that make a representation possible
  are bundled in a context object
• Possibility to vary couplings for multiple
  representations
• Contexts are linked in a inhertance hierarchy

Data Modeling
Visualization
Contexts
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Inside Giza Context
Dynamic nature of contexts (1/2)

• The task sets in Commands can modulate the
  coupling methods
• The representations react accordingly Components
  can observe changes in the data, and accessor
  objects can automatically adjust to changes in
  the coupling

Data Modeling
Visualization
Contexts
Tasks
User c
ommands
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Inside Giza Context
Why Contexts?

• Data structures, tasks and representations come
  in many colours
• Each context specifies a way to bridge the gap
  between the model , a representation, and user
  requirements
• The context determines the best possible match

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Inside Giza Context
Our Goal
Task
Context
Visualization
Data modeling
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Inside Giza Context
Contexts and structure (1/4)

• The data IS how you look at it
• We analyze or abstract models into structures by
  querying features of the data

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Inside Giza Context
Contexts and structure (2/4)

• The data IS how you look at it
• We analyze or abstract models into structures by
  querying features of the data
• Feature extraction is an active process, creates
  data, and ultimately the structure itself

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Inside Giza Context
Contexts and structure (3/4)

• The data IS how you look at it
• We analyze or abstract models into structures by
  querying features of the data
• Feature extraction is an active process, creates
  data, and ultimately the structure itself
• Each contextual system of feature extraction
  defines a different structure

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Inside Giza Context
Contexts and structure (4/4)

• The data IS how you look at it
• We analyze or abstract models into structures by
  querying features of the data
• Feature extraction is an active process, creates
  data, and ultimately the structure itself
• Each contextual system of feature extraction
  defines a different structure
• Structural analysis tools should look at the
  model through many such contextual systems

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Inside Giza Context
Future work and development

• Representation of graphs
• Representation of large hierarchical spaces
• Visualization application for software
  engineering

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Outline of presentation
Problem definition CHEOPS approach Giza
Framework Inside Giza Context How to reach us
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How to reach us
Cheops Innovator

• Luc Beaudoin (lubeaudo_at_crim.ca)

Cheops/Giza Implementation

• Luc Beaudoin
• Marc-Antoine Parent (maparent_at_crim.ca)
• Louis C. Vroomen (vroomen_at_crim.ca)

Director of the HCI Group

• France deVerteuil (fdev_at_crim.ca)

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URLs
HCI Group

• www.crim.ca/ipsi (Français)
• www.crim.ca/hci (English)

Main Cheops Page

• www.crim.ca/ipsi/cheops/index1.html (Français)
• www.crim.ca/hci/cheops/index1.html (English)

Graphical User Interfaces for Hierarchies A
Workshop

• www.crim.ca/vroomen/workshop/ (English)