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Space-Filling Representations: Treemaps and Beyond in Information Visualization, Slides of Computer Science

Kent State University (KSU) - Ashtabula Campus Computer Science

Hierarchies and trees in information visualization, focusing on space-filling representations like treemaps. the definition of hierarchies, shortcomings of node-link representations, and the advantages of space-filling methods. Topics include Treemap algorithm, variations, applications, and evaluations.

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2019/2020

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Hierarchies and Trees 2

(Space-filling)

CS 7450 - Information Visualization

March 9, 2006

John Stasko

Spring 2006 CS 7450 2

Hierarchies

•Definition

−Data repository in which cases are related to

subcases

−Can be thought of as imposing an ordering in

which cases are parents or ancestors of other

cases

Discover Slides of Computer Science Kent State University (KSU) - Ashtabula Campus

Partial preview of the text

Download Space-Filling Representations: Treemaps and Beyond in Information Visualization and more Slides Computer Science in PDF only on Docsity!

Hierarchies and Trees 2

(Space-filling)

CS 7450 - Information Visualization

March 9, 2006

John Stasko

Hierarchies

• Definition

− Data repository in which cases are related to

subcases

− Can be thought of as imposing an ordering in

which cases are parents or ancestors of other

cases

Spring 2006 CS 7450 3

Last Time: Node-Link Reps

Lamping & Rao

Card, Mackinlay & Robertson

Traditional

Hyperbolic tree

ConeTree

SpaceTree

Plaisant, Grosjean & Bederson

Node-link Shortcoming

• Difficult to encode more variables of data

cases (nodes)

− Shape

− Color

− Size

− …but all quickly clash with basic node-link

structure

Spring 2006 CS 7450 7

Treemap

• Example

Directories

Treemap

Demo - File and directory visualizer

Spring 2006 CS 7450 9

Treemap Algorithm

Draw()

Change orientation from parent (horiz/vert)

Read all files and directories at this level

Make rectangle for each, scaled to size

Draw rectangles using appropriate size and color

For each directory

Make recursive call using its rectangle as focus

Nested vs. Non-nested

Non-nested Tree-Map^ Nested Tree-Map

Spring 2006 CS 7450 13

Sample View 1

Subsystems in a software system. Each rectangle represents the non-comment source code in a subsystem. Area means size

New code

in this release

Size

Bug rates by subsystem and directory

Represents

new code

in this

release

Bug fixes

Added

functionality

Bars represent

individual

directories in

the subsystems

Sample View 2

Spring 2006 CS 7450 15

Tennis Viewing Application

• Analyze, review and browse a tennis

match

• Space-filling/treemap-like hierarchy

representation for a competition tree

• Shows match,sets,games,points

• Uses lenses to show shot patterns

• Red/green to encode two players

• Composite colors on top of each other

Jin and Banks

IEEE CG&A ‘

Visualization Make-up

Match

Composite

Games

Set

Spring 2006 CS 7450 19

Treemap Affordances

• Good representation of two attributes

beyond node-link: color and area

• Not as good at representing structure

− What happens if it’s a perfectly balanced tree

of items all the same size?

− Also can get long-thin aspect ratios

− Borders help on smaller trees, but take up too

much area on large, deep ones

Aspect ratios

These kinds of rectangles are visually unappealing

Which has bigger area?

Spring 2006 CS 7450 21

Variation

• Can rectangles be made more square?

……think about it……

• In general, a very hard problem!

Variation: “Cluster” Treemap

• SmartMoney.com Map of the Market

− Illustrates stock movements

− “Compromises” treemap algorithm to avoid

bad aspect ratios

− Basic algorithm (divide and conquer) with

some hand tweaking

− Takes advantage of shallow hierarchy

− www.smartmoney.com/marketmap

Wattenberg

Image on next slide CHI ‘

Spring 2006 CS 7450 25

SmartMoney Review

• Tufte-esque micro/macro view

• Dynamic user interface operations add to

impact

• One of best applications of InfoVis

techniques that I’ve seen

Other Treemap Variations

• Squarified treemap

− Bruls, Huizing, van Wijk, EuroGraphics ‘

− Alternate approach, similar results

Spring 2006 CS 7450 27

Square Algorithm Problems

• Small changes in data values can cause

dramatic changes in layout

• Order of items in a group may be

important

New Square Algorithms

• Pivot-by-size and pivot-by-middle

Shneiderman & Wattenberg

InfoVis ‘

Partition area into 4 regions

Pick pivot element Rp

Size: Largest element

Middle: Middle element

R 1 - elements earlier in list than

pivot

R 2 - elements in list before R 3 and

also that makes Rp have aspect

ratio closest to 1

Spring 2006 CS 7450 31

Slice-and-dice Cluster Squarified

Pivot-by-middle Pivot-by-size Strip

Showing Structure

• Regular borderless treemap makes it

challenging to discern structure of

hierarchy, particularly large ones

− Supplement Treemap view

− Change rectangles to other forms

Spring 2006 CS 7450 33

Variation: Cushion Treemap

Add shading and texture

to help convey structure

of hierarchy

Van Wijk & van de Wetering

InfoVis ‘

SequoiaView

www.win.tue.nl/sequoiaview/

File visualizer

built using

cushion treemap

notion

Demo

Spring 2006 CS 7450 37

Investment Portfolios

www.panopticon.com

Panopticon

Another Problem

• What if nodes with zero value (mapped to

area) are very important?

− Example: Stock or mutual fund portfolios:

Funds you don’t currently hold have zero

value in your portfolio, but you want to see

them to potentially buy them

Spring 2006 CS 7450 39

Space-Filling Representations: Treemaps and Beyond in Information Visualization, Slides of Computer Science

Related documents

Partial preview of the text

Download Space-Filling Representations: Treemaps and Beyond in Information Visualization and more Slides Computer Science in PDF only on Docsity!

Hierarchies and Trees 2

(Space-filling)

CS 7450 - Information Visualization

March 9, 2006

John Stasko

Hierarchies

• Definition

− Data repository in which cases are related to

subcases

− Can be thought of as imposing an ordering in

which cases are parents or ancestors of other

cases

Last Time: Node-Link Reps

Lamping & Rao

Card, Mackinlay & Robertson

Traditional

Hyperbolic tree

ConeTree

SpaceTree

Plaisant, Grosjean & Bederson

Node-link Shortcoming

• Difficult to encode more variables of data

cases (nodes)

− Shape

− Color

− Size

− …but all quickly clash with basic node-link

structure

Treemap

• Example

Directories

Treemap

Demo - File and directory visualizer

Treemap Algorithm

Draw()

Change orientation from parent (horiz/vert)

Read all files and directories at this level

Make rectangle for each, scaled to size

Draw rectangles using appropriate size and color

For each directory

Make recursive call using its rectangle as focus

Nested vs. Non-nested

Non-nested Tree-Map^ Nested Tree-Map

Sample View 1

New code

in this release

Size

Represents

new code

in this

release

Bug fixes

Added

functionality

Bars represent

individual

directories in

the subsystems

Sample View 2

Tennis Viewing Application

• Analyze, review and browse a tennis

match

• Space-filling/treemap-like hierarchy

representation for a competition tree

• Shows match,sets,games,points

• Uses lenses to show shot patterns

• Red/green to encode two players

• Composite colors on top of each other

Jin and Banks

IEEE CG&A ‘

Visualization Make-up

Match

Composite

Games

Set

Treemap Affordances