Academic journal article Cartography and Geographic Information Science

Expanding Display Size and Resolution for Viewing Geospatial Data: A User Study with Multiple-Monitor High-Resolution Displays

Academic journal article Cartography and Geographic Information Science

Expanding Display Size and Resolution for Viewing Geospatial Data: A User Study with Multiple-Monitor High-Resolution Displays

Article excerpt

Introduction

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 the need for new visualization formats that can make full use of high-resolution digital data. The research reported here explores the utility of a low-cost solution of mounting multiple-monitor displays to fulfill this need. By assigning experienced geospatial data users to perform map reading tasks on various display sizes and resolutions, this research investigates the possible task-completion benefits, usage strategies, and usability issues associated with using large, high-resolution multiple-monitor displays for geospatial data.

Map layout parameters restrain cartographers and the amount of information they can usefully display on a map. When working in the traditional paper map medium, cartographers must consider the constant tradeoffs between the size, scale, and coverage of a map (Figure la). Specifying the parameters of one of these aspects restricts the available options for the other two. For example, once the physical size of a 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 (Lloyd and Bunch 2003). Unfortunately, the desired specifications for all three variables are not always attainable.

With the advent of geographic information systems (GIS), digital maps viewed on computer monitors have become at least as commonplace as their paper map counterparts. Furthermore, the Internet provides rapid access to rich geographic data and imagery, and GIS tools encourage versatility in map design. Despite these advantages, however, computer cartography laces the same cartographic limitations as paper cartography. Computer screens are fixed in size and limited in resolution. The opposing requirements for greater map coverage area and scale of detail must compete because the physical size of the viewing area is fixed. Perceptually, users' needs for both greater context and visible detail are at odds (Figure lb). If users need to see more detail, they lose the overall context; however, if they view the entire coverage area, they lose access to fine detail. Typical computer displays therefore limit the viewer's ability to utilize digital maps and data sources because the user is visually constrained by the bounding bezels of a single desktop monitor.

[FIGURE 1 OMITTED]

To overcome the fixed-size limitation of computer monitors, panning and zooming functions are essential for navigation (Slocum et al. 2005). These tools allow users to capture desired coverage area and scale, providing the ability to quickly cycle back and forth between the two for comparison, if one static view does not suffice. Frequent panning and zooming, however, have major implications on map perception. Panning at a large scale creates a loss of context, as the entire map is not visible, while zooming out to obtain the full context alters the scale and results in a loss of detail (Brown 1993). High-resolution data and imagery can rarely be displayed to view their full extent and quality simultaneously.

One display method that overcomes the conflict between context and scale is the focus-plus- context screen. This interface combines a large, low-resolution display with an embedded display area of high resolution (Baudisch et al. 2002). While this is an improvement from single small displays, the interface still has a separation between context and scale. In this instance, only portions of the viewing area have both desired context and fine detail available. Moving beyond the locus-plus-context screens is the alternative option of a computer with the built-in capacity to support multiple monitors. Now that thin, flat, liquid crystal displays (LCDs) or plasma screen monitors have begun to replace bulky cathode-ray tube (CRT) monitorsthere is a means for making low cost, high-resolution displays by configuring multiple monitors to act as a single display (Hutchings et al. …

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