ENV 2006 CS2.1

Envisioning Information: Case Study 2

Scatter Plots on Handheld Devices

ENV 2006 CS2.2

Application

• This case study considers work by Buering et al at Konstanz

• Application is visualization of a book database of 7500 items on a PDA

• Technique is scatter plot

• Here sale price (Y) is plotted against year of publication (X)

• Potentially many items per pixel

• Multiple views awkward

• Case study: user evaluation of zooming versus fish-eye distortion

ENV 2006 CS2.3

Types of ZUI

• Two different zoom techniques:– Geometric zoom– Semantic zoom

• Geometric zoom: simple enlargement of the picture, content unchanged

– Eg PDF viewer

• Semantic zoom: content changes according to degree of zoom

– Eg Summary Thumbnails approach to web browsing

Summary Thumbnails (Lam, Baudisch, CHI 2005)

ENV 2006 CS2.4

Geometric-semantic ZUI

• Buering suggests a geometric-semantic ZUI

– Smooth transition from scatterplot overview to detail information in a single view

– Pixels (a) transform to rectangles (c) to record cards (d) to book details (f)

• To avoid ‘desert fog’ zooming is always on an object, not empty space.. Think about it!

ENV 2006 CS2.5

Fish-eye Distortion

• Box acts as focus region to generate fisheye view (b), then (c)– Enlarged focus, shrunk surround

• Tapping item returns book details (d)

ENV 2006 CS2.6

User Evaluation

• Hypothesis 1: Task completion time faster for fish-eye– Prior evidence that fish-eye speeds navigation and avoids

unnecessary exploration

• Hypothesis 2: Users would prefer the ZUI– Prior evidence that artificial distortion is not liked

– Also ZUIs are used in some common applications such as games

• Examples of tasks:– Visual scan - How many books published since 2000 at price of

EUR 30?

– Information access - Who is author of most expensive book in 2005?

– Comparison of information objects - Between Aug and Nov 2005, 4 books were published at EUR 8.53… which one had most pages?

ENV 2006 CS2.7

Results

• H1: Fish-eye faster– Contradicted, both about the same overall

– For navigation, fish-eye took fewer actions – but action of drawing focus box more demanding

• H2: Users prefer ZUIs– Contradicted, more preferred fish-eye

– Better in terms of orientation and more precise navigation

– Goes against some other studies – does the axis aligned nature of scatter plots lend itself well to fisheye?