Chapter 1: Introduction and Statement of Purpose 1.1 ...€¦ · Chapter 1: Introduction and Statement of Purpose 1.1 Introduction Cartographers are restrained by the amount of information

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Chapter 1: Introduction and Statement of Purpose

1.1 Introduction

Cartographers are restrained by the amount of information they can effectively display on

a map because of the limitations imposed by the physical size of the desired product medium.

When working in the traditional paper map medium, cartographers must consider the constant

tradeoffs between the size, scale, and coverage of a map (Figure 1.1a). Specifying one of these

aspects restricts the available options for the other two. For example, once the physical size of

the map is set, the cartographer must prioritize the importance of coverage area and scale, as an

increase in one will result in a decrease in the other. It is not always practical or possible to

attain an effective balance between the three variables.

With the advent of geographic information systems (GIS), digital maps viewed on

computer monitors have become as commonplace as their paper map counterparts. Computers

have greatly aided cartography, with the Internet providing rapid access to rich geographic data

and imagery while GIS tools allow for map design versatility. Despite these advantages,

computer cartography faces the same cartographic limitations as does paper cartography.

Computer screens are fixed in size. With viewing area fixed, the opposing requirements for

greater map coverage area and scale of detail compete (Lloyd and Bunch 2003). Perceptually,

users’ needs for both greater context and visible detail are at odds (Figure 1.1b). If users need to

see more detail, they lose the overall context; however, if they view the entire coverage area,

they lose the available fine detail. Typical computer displays therefore limit the ability to utilize

fully digital maps and data sources because they are visually constrained by the bounding bezels

of a single desktop monitor. While available panning and zooming tools allow users to navigate

precisely to what they want to view, the fixed viewing window forces them to frequently zoom

and pan to acquire the context and scale of detail desired (Slocum et al. 2005). Readily available

high-resolution data and imagery can rarely be viewed at its full extent and quality

simultaneously.

Currently, bulky cathode ray tube (CRT) monitors are being supplanted by thin, flat,

liquid crystal display (LCD) or plasma screen monitors. In addition, many computers have the

built-in capability to support multiple monitors. These coincident trends provide the means for

making low cost, high-resolution displays by configuring multiple monitors to act as a single

display (Hutchings et al. 2004) (Figure 1.2). Individual projectors only increase display area,

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making high-quality imagery appear pixilated when viewed at close range. However, multiple

monitors increase display area and maintain high-resolution across the entire display so that

imagery appears clearly even when users are close to the screen (Bezerianos & Balakrishnan

2005). Such displays are useful for a variety of computing tasks such as group collaboration,

viewing multiple applications simultaneously, or enhancing video gaming experiences. In

particular, maps displayed on multiple monitor configurations provide a new geospatial

visualization opportunity by incorporating both larger coverage areas and finer detail into a

single view. The previously fixed small size of the viewing area is expanded, reducing

constraints in achieving a balance between context and detail.

The effectiveness of large, high-resolution displays, especially for viewing maps and

imagery, has not been studied thoroughly. Current research on multiple monitor displays has

largely been conducted by computer scientists specializing in human-computer interaction. In

most of these studies, typical office computing tasks (Ball and North 2005a; Grudin 2001;

Simmons 2001; Tan & Czerwinski 2003; Czerwinski et al. 2003), video game interfaces, virtual

environments (Ni et al. 2006; Polys et al. 2005), or perception tasks (Tan et al. 2003) were the

focus of usability research and data collection. The few studies that have involved geospatial

information and visualization were conducted using subjects with little to no map reading

experience (Ball and North 2005b; Ball et al. 2005).

1.2 Statement of Purpose

Geographic information systems (GIS) and high-resolution imagery have an increasingly

prominent role in many research institutions, government organizations, and private sector

businesses. This trend creates a need for new visualization formats that can make full use of

high-resolution digital data. One possible low-cost solution for this need is the use of multiple

monitor displays that increase display area while also maintaining high-resolution. Research

concerning multiple monitors has mainly been conducted within the field of computer science

where geospatial applications compete with other programs and tasks for research attention.

The purpose of this research is to gain a better understanding of the utility of multiple

monitor displays for working with geospatial information. By having experienced geospatial

data users perform map reading tasks on various display sizes, I explored the possible task-

completion benefits, usage strategies, and usability issues when using large, high-resolution

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multiple monitor displays for geospatial data. Since multiple monitor displays allow for greater

coverage and greater detail to be viewed at the same time, I hypothesized that, overall, subjects

on larger displays would perform more accurately and efficiently than subjects using one desktop

monitor. However, I also hypothesized that such trends may not hold for every map and task

type, with simpler maps and accompanying tasks accomplished just as accurately and efficiently

on a single monitor as on larger displays. This research will contribute additional understanding

to the areas of visualization, perception, and map reading as well as providing new insight on the

usability of low-cost, large, high-resolution displays for geospatial work in educational

institutions, businesses, and government agencies.

This thesis has two additional chapters. Chapter 2 presents a review of previous work in

both cartography and computer science relating to visualization and the increase in use of

multiple monitor display configurations. Chapter 3 focuses on the results of my user study

exploring map reading task performance using different display sizes. It is written in preparation

for submission to the journal Cartography and Geographic Information Science.

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References

Ball, R. and C. North. 2005a. An analysis of user behavior on high-resolution tiled displays. In

International Conference on Human-Computer Interaction (INTERACT ’05), 350-364.

Ball, R. and C. North. 2005b. Effects of tiled high-resolution display on basic visualization and

navigation tasks. In Extended Abstracts CHI ’05, 1196-1199.

Ball, R., M. Varghese, B. Carstensen, E. D. Cox, C. Fierer, M. Peterson, and C. North. 2005.

Evaluating the benefits of tiled displays for navigating maps. In International Conference

on Human-Computer Interaction (IASTED-HCI ’05), 66-71.

Bezerianos, A., and R. Balakrishnan. 2005. View and space management on large displays. IEEE

Computer Graphics and Applications 25 (4):34-43.

Carstensen, L. W. 2005. Geog/Geos 4084 – Text: Virginia Tech University Printing Services.

Czerwinski, M., G. Smith, T. Regan, B. Meyers, G. Robertson, and G. Starkweather. 2003.

Toward characterizing the productivity benefits of very large displays. In International

Conference on Human-Computer Interaction (INTERACT ’03), 9-16.

Grudin, J. 2001. Partitioning digital worlds: Focal and peripheral awareness in multiple monitor

use. In Human Factors in Computing Systems (CHI ’01), 458-465.

Hutchings, D. R., M. Czerwinski, B. Meyers, and J. Stasko. 2004. Exploring the use and

affordances of multiple display environments. In Workshop on Ubiquitous Display

Environments at UbiComp 2004, 1-6.

Lloyd, R., and R. L. Bunch. 2003. Technology and map-learning: Users, methods, and symbols.

Annals of the Association of American Geographers 93 (4):828-850.

Ni, T., D. A. Bowman, and J. Chen. 2006. Increased display size and resolution improve task

performance in information-rich virtual environments. Graphics Interface 2006:139-146.

Polys, N. F., S. Kim, and D. A. Bowman. 2005. Effects of information layout, screen size, and

field of view on user performance in information-rich virtual environments. In ACM

Virtual Reality Software and Technology 2005, 46-55.

Simmons, T. 2001. What’s the optimum computer display size? Ergonomics in Design Fall

2001:19-25.

Slocum, T. A., R. B. McMaster, F. C. Kessler, and H. H. Howard. 2005. Thematic Cartography

and Geographic Visualization. Second Edition ed. Upper Saddle River: Pearson Prentice

Hall.

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Tan, D. S., and M. Czerwinski. 2003. Effects of visual separation and physical discontinuities

when distributing information across multiple displays. In Computer-Human Interaction

Special Interest Group of the Ergonomics Society of Australia (OZCHI), 184-191.

Tan, D. S., D. Gergle, P. G. Scupelli, and R. Pausch. 2003. With similar visual angles, larger

displays improve spatial performance. In Human Factors in Computing Systems (CHI

’03), 217-224.

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Chapter 1 Figures

Figure 1.1. A) Tradeoff relationships in map design B) Tradeoff relationships for map

perception (modeled after Carstensen 2005). Mathematical symbols note the positive and

negative relationships between items.

Physical Size

Coverage Area

Scale _

+ +

Physical Size

Context Detail _

+ +

A. B.

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Chapter 1 Figures

Figure 1.2. Multiple monitor display constructed of nine 17” flat screen LCDs (3840 x 3072

pixels).